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450 Horsepower – 480 LB-FT torque 396 Big Block Chevy

450 Horsepower – 480 Lb-Ft Torque 396 Big Block Chevy

JMac Performance built a 450 Horsepower – 480 LB-FT Torque 396 Big Block Chevy. The goal with this build was a solid street engine that could be a weekend cruiser with enough attitude to perform well at the track.


The Foundation
Block and Cylinder heads

The build started with a rare factory 4 bolt main 396 block # 3855962.

The block received the usual machine work: magnaflux’d , bore and honed .030 over with a torque plate, decked, and line honed.

I always use ARP main bolts for added strength

You can tell it’s a 396 block by the intake valve reliefs machined into the deck

To help eliminate cracks all the extra casting flash was ground off




The oiling holes were smoothed and lifter valley was cleaned up.


Before                                                                    After

Cylinder heads

Stock # 3872702 cylinder heads with a 98 cc closed combustion chambers were used. They received magnfux’d, decked, new valve guides, 3 angle valve job, and Manley 2.07″ intake and 1.725″ exhaust stainless steel valves.

Because the 396 has a small 4.125″ bore cylinder I resisted the temptation to install larger valves.  I did use a .100″ longer valve to accommodate the taller lift of a bigger camshaft.

The cylinder heads received a pocket porting where the bowl under both valves were opened up, valve guides were narrowed, and the exhaust ports were polished.

In the 60’s gasoline had lead in it, not so much in 2017. To accommodate running on unleaded fuel harden valve seats were also installed.

To ensure no oil gets into the combustion chamber the guides were cut so Viton oil seals could be installed.

The Bottom End

This 396 already had a great factory forged steel crankshaft. It was turned .010 under on both the mains and the rod journals, polished, oil holes were chamfered, and balanced.

Stock size 6.135″ Scat full floating connecting rods with ARP bolts, forged Icon pistons, and Hastings single moly piston rings were used.  Piston to wall clearances were set between .0035″ – .004″.

The pistons have a small dome which creates a total of 9.5/1 compression with the 98 cc combustion chambers.


Main and Rod clearances were set to .00275″and .0025″ respectively and the crankshafts end play was set to .005″


The oil pump is a standard volume, standard pressure Mellings.  Unless you’re planning on running a 7 quart oil pan or larger a hi-volume pump is not recommended. The oil pump received the usual blue printing to ensure the relief valve worked properly and the cover to gears clearance was correct.

Notice the oil pickup is tack welded to the pump to ensure it does not come loose

The pistons were set at .015″ below the deck

The Valve Train

The heart of the valve train is a Comp Cams custom grind billet hydralic roller # 2640-16 Intake .510″ lift 230 @ .050 –  exhaust .520″ lift 236 @ .050 on a 110 lobe center.

Note: because this is a 1966 block the rear camshaft main journal and the rear cam bearing both have a groove machined in them. Using a non-grooved camshaft and rear bearing in the earlier block with result in engine failure!!

Finishing the rest of the valve train are Comp Cams hydraulic retro-fit roller lifters, Comp Cams one piece push rods, and Scorpion 1.7 ratio roller rocker arms

A double roller timing chain with a Torrington bearing a long with a nylon cam button was installed.  Because the block was line honed a .005″ smaller timing chain had to be used.

The cam was set at 2 degrees advanced


Induction, fuel system, and ignition

A Quick Fuel 750cfm double pumper carburetor, Weiand duel plan intake manifold, Edlebrock hi volume mechanical fuel pump and a HEI distributor was used.

The HEI distributor was recurved to have 14 degrees of timing at idle and 38 degrees of timing at 3800 RPM

This engine has the performance needed to be successful at the drag strip or auto cross but has the manners to be a great street cruiser

Click on the link below to see and hear it run on the engine stand

JMac 450 Horsepower – 480 Lb-ft Torque 396


450 Horsepower – 500 LB-FT Torque Ford 351W (Windsor) 393 Stroker

450 Horsepower – 500 Lb-Ft Torque Ford 351W (393 Stroker)

JMac Performance put together a 450 Horsepower – 500 Lb-Ft torque 9.75/1 Fuel injected 351 Windsor/393 stroker Small Block Ford. The goal with this build was low RPM high Torque that could move a 4000 pound 56′ Mercruiser, run on pump gas, and have the street manners to be a daily driver.

Ford 351W (393 Stroker) “The Foundation”

I started the build with a mid-1980’s non-roller 351 W, 2 bolt main, 1 piece rear main seal block. I chose the non-roller block because some of the newer late 80’s/early 90’s roller blocks can have stress cracks in the valley above the cam bearings. The non-roller 351W blocks can be easlly converter to roller blocks and have proved to be crack free.


The block recieved the usual hot tank, magniflux, .030 over bore and hone with a torque plate, line hone, and decking.  I also ground off all the extra casting flash and opened up the oil holes in the lifter valley to ensure the oil returns to the oil pan without restriction.

Before – from the factory



After it has been opened up


Grinding off the excess casting flash makes the engine easier to work on and helps eliminate stress cracks.


Ford 351W (393 Stroker) “Bottom End”

Over 500 Lb-Ft of torque can put quite a strain on the main caps.  A main cap girdle was used along with ARP main cap bolts to ensure everything stayed tight and in-line.


Because of the 3.850″ stroke of the crankshaft the main gridle needed to be clearanced. The throw of the crankshaft and the big end of the connecting rods need a minimum of .060 clearance.


A forged SCAT 3.850″ stroke crankshaft, forged SCAT 6.2″ connecting rods with ARP bolts, forged 4.030″ ICON Pistons, Speed-pro single moly piston rings, and Cleveite bearings were used to complete the bottom end.


Ford 351W (393 Stroker) “Oiling System”

A mellings high volume oil pump was used to keep the bottom end well lubed. The main gridle needed to be clearanced to ensure a proper fit between it and the oil pump. To keep the integrity of the oil pump it’s better to grind the main gridle not the oil pump.


From the factory the oil holes that drain from the cylinder heads back to the oil pan can sometimes be mis-aligned. To ensure oil flows freely the holes were opened up and chamfered.


With all JMac Performance engine builds the oil pump is disassembled to ensure all clearances are correct and to verify the relief valve and  pressure spring work freely.


Ford 351W (393 Stroker) “Cylinder Heads and Induction System”

AFR Renegade 185 cc heads were used, they are CNC ported and are an exceptional cylinder head. A larger cylinder head would have made more horsepower, However the customer stressed they wanted low RPM torque over higher RPM horsepower. The smaller cylinder heads help increase the intake velocity at lower RPM thus creating a more responsive and higher torque engine.


Because the customer wanted a maintenance free fuel system with maximum drivability the FAST EZ fuel injection system was used.  It is a self learning, extremely easy system to install and use and no tuning is needed!


I used an Edelbrock RPM Performer dual plane intake manifold. It matched the operating RPM of the engine very well, from 2500 – 6500 RPM. I have found that most fuel injection systems do not like full dual plane intake manifolds. So, about 1/2″ was removed from the intake manifolds center divider to help both banks equalize better.

Before                                                                                            After


Ford 351W (393 Stroker) “Valve Train”

As I mentioned earlier a non-roller block was used over the crack prone later roller blocks. A hydraulic roller camshaft and valve train was to be used so I convered the block to a roller type by installing a Comp Cams conversion kit.  It allows the use of less costly non-link bar lifters. A lifter valley “spider” and “wish bone” alignment links are adapted to the block.


Two small 1/4″-20 holes are drilled and tapped into the lifter valley floor to hold down the lifter “Spider”. The edge of the lifter valley where the lifter wish bones links sit are clearanced to ensure full movement.


A set of Dura-Bond high performance camshaft bearing were installed.


A Comp Cams XR264RF-HR10 small base circle camshaft was used. A small base circle camshaft is required to ensure proper oiling to the lifters. If a standard base circle camshaft is used with the non-link bar style roller lifters they extend to far out of the lifter bore thus blocking the oil passages and greatly reduce the oil moving through the system.


Although it is an non-roller block the roller thrust plate can still be used to keep the camshafts end play in check. Because the block was line honed a -.005 smaller double roller timing chain with a needle bearing thrust washer was used. Notice the flat head allen screws used to hold the thrust plate in place, they are needed to create a flat surface for the timing chain thrust bearing.


To top of the valve train a set of Trickflow 7.600″ .080″ thick push rods were used along with a set of 1.6 ratio Hardland Sharp full roller rocker arms.


Ford 351W (393 Stroker) “Test run”

With the engine complete all that was needed is a quick test run on the engine stand to ensure all systems worked properly.  After setting the intial parameters on the FAST EZ fuel system the engine started right up. The timing was set to 14 degrees at idle of 850 RPM and 36 degrees total all in at 3500 RPM.  As the engine ran I could see the air/fuel ratio’s begin to reach their target settings. The engine is ready to install in the 56″ Mercury Mercuriser and after about a tank of fuel will be fine tuned for many years of trouble free driving.

   Click here to see the engine on the run stand


450 Horsepower – 500 Lb-Ft Torque Ford 351w / 393 stroker engine.

Contact if you’d like more details on this engine build.

600 Horsepower 350 Small Block Chevy

JMacPerformance dyno tunes a 600 Horsepower 350 Small Block Chevy


The 350 was built by a high school friend of mine Rodney Reimer.

His 68′ El Camino which was featured in the pages of Car Craft January 2009 has a turbo 400 transmission with a 5500 RPM stall converter, 12 bolt rear-end with 4.30 gears, and 10″ wide Hoosier quick street DOT rear tires.

The goal of the build was to make 600 Horsepower on E85 fuel

The build started with a stock GM 4 bolt main block that received the usual machine work: Bored .030 over, decked, and line honed.  It received a full fill of blok-hard to increase the integrity of the block and for a little added security

The list of major compentents: 

357 ci
4.030 forged pistons – 12.2/1 compression
Heads Profiler 210cc and 2892 Super Victor manifold prepared by Juan Mendoza / Flow Technology
Pro Systems Carburetor E85 950
Custom Comp Cams XE 292
solid roller / steel billet  108 lsa
1.6 intake / 1.5 exhaust rockers
Schoenfeld 1 3/4 headers
Thru 3″ magna flow mufflers

After running the engine for 20 minutes on the dyno the valve lash and all the fasteners were checked. We did a few quick pulls to optimize the timing at 38 total degress and ensure the air fuel ratio was in a safe 12.5/1 range.

The engine ran flawlessly making 601 Horsepower and 497 lb-ft of Torque

Image (2) Image

The 601 Horsepower will get his El Camino 10 second quarter mile ET’s and with the 12.2/1 compression ratio on E85 fuel will make it very street able.

440 Horsepower – 470 Ft-Lb Torque 383 Small Block Chevy

440 Horsepower – 470 Ft-Lb Torque 383 Small Block Chevy

JMac Performance put together a 440 Horsepower 9.25/1 383 Small Block Chevy. The goal with this build was to make a strong streetable engine that has good street manners to be a daily driver and enough power to be competitive at the track or in an off-road vehicle. Here are the details from the parts selection to the dyno testing.


“Block Prep”

I started the build with a good factory 4 bolt main block. It was magnifuxed to make sure it had no cracks, bored and hone .030″ over (with a torque plate), line honed, then decked to ensure proper piston to cylinder head clearance and proper compression quench. All the block casting flash was removed and the oil return holes in the lifter valley were cleaned up and radiused.

16 18 20 21  24  OLYMPUS DIGITAL CAMERA   

Once all the machine work was done I cleaned all the bolt holes with thread chasers. I also chamfered the top of the cylinder head bolt holes to ensure the heads would sit flush on the blocks deck. The oil galley holes behind the timing chain were tapped so threaded pipe plugs could be installed.


The bottom of the cylinder bores were sanded with emery cloth to eliminate the sharp edge left by the machine work which can scuff of the piston skirts.

Bottom of cylinder radiused Block clearanced

The block was thoroughly cleaned but not before the main galley plug was removed.  Dirt and small metal shavings from the machine work usually hide behind this plug, if it is not removed and cleaned all the residue left behind will be cycled through your new engine at start up.


Once the machine work was complete and the block had been prepped and cleaned I started assembling the bottom end.

“The Bottom End”

I wanted the bottom end to handle at least 600 HP in case there were any power upgrades in the future. I used a SCAT bottom end kit with 3.75″ stroke crankshaft, 6.0″ connecting rods, KB pistons with floating wrist pin, Speed-Pro moly piston rings, and Clevite main and connecting rod bearings. Note: all the bottom end bearings received a light chamfering with a bearing sharper to eliminate any burrs.


Before I started assembling the bottom end I installed Dura bond performance cam bearings.


Next I installed the main bearings and checked the clearances, all the were at .0025″. I installed the crankshaft, torqued down the main cap ARP bolts (75 lb on the inner main bolts, 65 lb on the outer main bolts) then I checked the end play of the crankshaft which was .004″.


Next the pistons rings were cut and all the ring gaps were checked (.026″ top – .022″ Second, .015″ oil ring), the piston to cylinder wall clearances were verified (.0026″ – .028″), the connecting rod bearing clearances were checked, all were at  .0022″, the pistons were installed on the connecting rods, the rings installed on the pistons, the pistons installed in the cylinders, and the connecting rods were installed on the crankshaft by torqueing the ARP con-rod bolts to 45 lb. Finally the connecting rod side clearances were checked (.017″ – .019″).


Finishing the bottom end I installed a Mellings standard pressure/standard volume oil pum and hardened oil pump shaft. I adjusted the oil pump pickup to oil pan clearance to 3/8″ and tack welded the pickup to the oil pump, and finally installed a crankshaft oil scraper. I blue-printed the oil pump to ensure the clearances were correct and ensured everything was in good working order before bolting it to the rear main cap and bolting down the oil pan.


Here’s a copy of the clearance spec. sheet

383 build sheet

“Valve Train and Cylinder Heads”

“Camshaft and related parts”

A complete Comp Cams 12-212-2 valve train kit was used: camshaft, lifters, push rods, valve springs, retainers, and locks. The cam timing was degreed and showed 2 degrees of advance. Becasue the block had been line bored an upgraded  -.005″ timing chain had to be used, I chose one with a torrington bearings to reduce friction on the block.

Comp Cam street 383


“Cylinder Heads”

A set of iron World Product Sportsman II 200 cc cylinder heads were used.  They were pocket ported, the bowls below the valve seats were opened up and the intake valves received a 52 degree back cut to help with low lift flow numbers.  The heads came with stainless steel 2.02″intake and 1.60″ exhaust valves. The heads were taken to Saddleback College in Mission Viejo Calif. and placed in the Super-flow flow bench to record the flow numbers. The cylinder heads combustion chambers were cc’d and found to be at 78cc’s. With a flat top piston and zero deck height the static compression ratio was 9.25/1.

World heads flow numbers

The valve spring height was set to 1.800″ and the valve spring retainer to valve guide seal clearance was checked, there was plenty of room with over .850″. The push rod length and rocker arm geometry was checked. Notice: the use of Crane Cams full roller rocker arms and poly locks.


“Induction and Ignition”

Topping off the 383 is an Edelbrock RPM Performer intake manifold. It was match ported to the heads and the dividing bar between the dual planes was contoured to ensure equal distribution of fuel to all the cylinders. You can see the intake runners before and after match porting.


“Ignition system”

An aftermarket HEI distributor was used however, most aftermarket HEI distributors have a very slow/conservative timing curve.  To help increase torque and low end horsepower I reset the distributor timing curve.  I closed up the mechanical/centrifugal advance by welding up the advance slot. I took about .080″ out of the slot to reduce the total mechanical advance timing by 6 degrees. This allowed me to use a slightly higher initial timing (16 degrees instead of the usual 8-10 degrees) while keeping the total timing at 38 degrees. I then installed lighter advance springs to have all  timing advance in by 3500 RPM. On the dyno this proved to add 8-10 ft-Lb torque between 2500 to 3500 RPM. To make sure the spark made it to the spark plugs MSD spark plug wires were used.

HEI Distributor curve




I used a Mighty Demon 650 CFM double pumper carburetor. It has removable idle and high speed air bleed jets so the fuel curve can be tuned.

An Edelbrock 650 carburetor was initially used during the dyno testing, the Demon carburetor was worth 20 more Horsepower and 20 more ft-lb Torque throughout the entire RPM range.


“Dyno testing Judgement day” 

I bolted the 383 up to the DTS engine dyno at Saddleback College in Mission Viejo, Calif. to see what it could do. After a 20 minute initial run time to break in the camshaft I did a few low rpm pulls to set the timing, 38 total degrees is what worked best. Next I tuned the carburetor with a few main and high speed air bleed jet changes to get the fuel curve and air fuel ratio correct. Then I did a few full pulls from 2500 to 5800 rpm. It made 473 ft-lb Torque @ 4100 and 442 Horsepower @ 5600.  It made 418 ft-lb torque @ 2500 and never made under 400 ft-lb torque through the entire rpm range.

Street 383 Graph  Street 383 dyno sheet


Click the link below to watch the engine on the dyno

440 HP – 473 TQ Street 383 Small Block Chevy on the Engine Dyno

Click the link below to see a close up of the engine on the dyno

440 HP – 473 TQ Street 383 close up on the dyno

This engine is the best of all worlds!  With it’s pump gas friendly 9.25/1 compression it can easily be used as a daily driver. With 442 Horsepower and 473 ft-lb of Torque it can get the average muscle car or street rod into the 11’s at the drag strip or dominate the off road in a 4 X 4 truck.

380 Horsepower- 460 ft-lb Torque 383 Small Block Chevy

JMacPerformance built a mild street 383 Small Block Chevy.  The engine was intended for a 41 Ford pickup street rod that would be pulling a trailer, so the goal was to make as much Torque as possible while keeping mild street manners and daily reliability.


The build starts with a standard 010 350 block that was given the usual bore and hone (with torque plate), decked, magnifluxed, and pressure tested. A balanced SCAT bottom end kit was added with KB hypereutectic dished pistons for a pump gas friendly 9/1 compression, 3.75 stroke cast steel crankshaft, 5.7″ connecting rods, and clevite bearings.


A factory windage tray, Mellings HV oil pump, and 5 quart oil pan were added


Knowing that torque was the goal I used a pair of Pro Topline Vortec style aftermarket heads. They were affordable, very high quality, and the Vortec design was intended to increase torque which fit this build perfectly. They were pocket ported and had stainless steel Ferrea valves added to ensure good flow numbers.


The valve train was controlled by a 264/270 Iskenderian Mega camshaft, lifters, valve springs, steel retainers, and clips.  Custom length one piece Comp Cams chrome moly push rods where used along with self-aligning full roller rockers.


Topping off the engine is a Edelbrock Vortec Air-Gap RPM Performer intake manifold, Edelbrock 750 Carburetor, and HEI distributor.


Once bolted up to the dyno the usual procedures were used to ensure the camshaft was broken-in properly.  After a few pulls to the optimize timing and jetting we had 380 Horsepower @ 4900 RPM and 460 ft-lb Torque @ 3400.

The engine had over 400 ft-lb of torque from 2500 to 5000 RPM.  

  383 dyno sheet  383 dyno graph

This 383 has that high performance / muscle car sound without being over the top. It will work for any street rod, muscle car, or truck and with the pump gas friendly 9/1 compression it is mild enough to be used as a daily driver.

455 Oldsmobile Fuel Injected “Stump Puller”

455 Oldsmobile Fuel injected “Stump Puller” 

The goal with this build was to create an engine with exceptional low RPM manners, run well on 91 octane, and have muscle car performance.

It ended up with over 400 horsepower and over 500 ft-lb torque, all on 91 octane fuel


“Getting to the bottom of the 455 Olds build”

As with all JMac built engines we started the build with the bottom end. I using a stock “F” 455 block, stock iron crankshaft, and stock connecting rods.  All the parts were magnifux’d for cracks, the block was bored and honed .030 over with a torque plate, the connecting rods had ARP bolts installed then resized, the crankshaft had the oil holes chamfered, and then had the journals polished.  

When most people talk about 455 Oldsmobile engines the subject of a poor oiling system usually comes up. Oldsmobile 455 engines have a history of low oil pressure and bottom end oil starvation, we address both on this build.

Addressing the low oil pressure and oil starvation

I started with a Mellings standard pressure/standard volume oil pump which I blue printed to insure all the clearances were correct, than I added an .080 shim to the spring which adds a little more pressure at idle.  

Melling M22F - Melling Oil Pumps

Many people try adding a high volume pump to address the Olds 455’s oiling issues but in stock form these engines have a very poor oil return from the heads to the pan.  A high volume oil pump increases the problem by pumping more oil up top and potentially draining the oil pan in the process.

Next I addressed the oiling system in the block.  If you take a look at the oil passages in the Olds 455 block they’re quite large. Because of the way the oil flows more of the oil is directed to the camshaft, push rods, and rockers arms leaving less where it’s needed at the bottom end.  So I added oil restrictors to the # 2, 3, and 4 main oiling passages between the main and cam bearings. This limits the oil going up top and increases the oiling to the mains bearings.


Next I verified the connecting rod and main bearing clearances were within specification.  The rule of thumb is .001″ of clearance for every 1″ of crankshaft journal diameter. However, the Olds 455 has a 3″ main journal diameter and 2.5″ diameter on the rods, that would call for .003″ clearance on the main bearings which is too wide for a street engine, especially one that will run consistently at low RPM.  So I tightened the clearances to .0025″ on the mains bearings and .002″ on the connecting rod bearings.

  I then addressed the poor oil return from the heads to the pan.  I opened up the return holes in the heads, radius the holes, and ground a slight groove in the lifter valley from the heads to the return holes in the block to aid quicker oil return to the pan. I polished the walls of the lifter valley which helps the oil return to the pan quicker.



Finally I added a new 5 quart oil pan along with a crankshaft oil scraper to help keep as much oil in the pan as possible while freeing up a few extra horsepower in the process.


The rest of the bottom end

Olds 455’s are not known for their robust main caps so I added ARP main cap bolts for some added insurance. Forged pistons, moly rings, and clevite bearings finished off the rest of the bottom end along with balancing everything before installation.

“Cylinder heads and valve train”

Cylinder Heads

I started with a set of 455 “G” cylinder heads, I used them because they already have harden exhaust seats installed from the factory which is needed when using unleaded pump gas.


The “G” heads came with a small 2.00″ intake valves so I upgraded to larger stainless steel 2.072″ intake valves and 1.625″ exhaust valves, the seats were cut with a 3 angle valve job. Then the heads were treated to a mild porting where the bowl under the valve seats were opened up.  The intake and exhaust ports were smoothed and cleaned up. With the 80cc combustion chamber and dished forged pistons the static compression ratio is 9.25/1 which works well with 91 octane pump gas.


Olds 455 cylinder heads have a history of running hot and cracking between the two center exhaust ports, this is because both inside exhaust ports flow into the crossover port that runs under the intake manifold.  To reduce the buildup of heat and to help direct the hot gasses out of the head more quickly I filled the crossover port in the heads with zinc. This greatly reduces the heat that is absorbed in the head which helps increase power and eliminates the potential for heat related cracks.


   Camshaft and valve train

Because this engine is going to be used as a freeway cruiser with 3.20 rear end gears and an overdrive transmission the camshaft had to be pretty conservative. A hydraulic flat tappet Comp Cams XE256H was used along with Comp Cams lifters, push rods, valve springs, locks, retainers, and double roller timing chain.  


Stock Olds 455’s have pedestal type non-adjustable rockers arms, so a set of adjustable roller tip rocker arms were installed along with Comp Cams push rod guide plates.


“Induction system and ignition”

Induction system

To accent the low RPM drivability an Edelbrock Performer intake manifold was used, this matched the target RPM of the camshaft very well. A FAST EZ fuel injection system was used instead of a carburetor. I have done hundreds of dyno tuning sessions and I have to say the FAST EZ system was by far the best and easiest system I have ever use and tuned!



 Ignition system

The ignition system is a basic HEI distributor, I added an upgraded coil and changed the timing curve so a higher initial timing could be used, this again accented the low RPM drivability of the engine. Finishing off the ignition system was a set of MSD 8.5 mm plug wires and Autolite sparkplugs.

photo 4

“Exhaust system”

A set of long tube 1 3/4″ primary and 3″ collector headers for a cutlass and a pair of Magnaflow mufflers were used during the dyno session.


“400 HP – 500 Ft-Lb Torque

Big Block 455 Oldsmobile Judgement Day”

We bolted the 455 Olds to the DTS engine dyno to see what kind of power it would make. Connecting the FAST EZ EFI system to the engine was actually much easier that I had anticipated, they ready made everything Plug-and-Play. I ran the engine for 20 minutes to break-in of the flat tappet camshaft and allow the EFI system to learn what the engine needed. After a 10 minute cool down I began tuning with a couple of quick low RPM pulls to find the best timing at 36 degrees and insure proper oil pressure.  The oil pressure at idle was a solid 30 PSI and climbed to a stable 50 PSI at 2500 RPM.


After 8 pulls the engine made 404 Horsepower @ 5200 and a “stump pulling” 521 Ft-Lb torque @ 3300.  It made 460 Ft-Lb torque at 2500 and never dropped below 400 Ft-Lb torque from 2500 to 5200 RPM!

Click on the link below to view the dyno pull

455 Oldsmobile 404 Horsepower – 521 Ft-Lb Torque

     455 Dyno Sheet  455 Dyno graph 1

With that much torque at such a low RPM this engine will make any Street Rod, Muscle Car, or Ski boat run extremely well!

Contact if you’d like more details on this engine build.

550 Horsepower 496 Big Block Chevy

JMacPerformance puts together a budget 496 Big Block Chevy.  The goal is to assemble a pump gas 500 + horsepower,  maximum torque big block on a limited budget.  A SCAT bottom end kit is used a long with –  Comp Cams flat tappet camshaft  –  Brodix Race Rite oval port head  –  Edelbrock Air-gap manifold and  –  Demon 850.


550 Horsepower 496 Big Block Chevy “The Beginning” 

The build starts with a standard 2 bolt main 454 block;  with the usual machine work (bore .030 over, decked, and line honed) a SCAT bottom end kit is installed.  The kit consists of a cast steel crank, 6.835″ connecting rods, KB hyperutectic pistons, Clevite bearings, and a Melling high volume oil pump.



550 Horsepower 496 Big Block Chevy “Heads – Valve train”  

A Comp Cams XE284H flat tappet camshaft and lifters were used a long with Comp Cams push rods, and Crane Cams 1.7 ratio rocker arms.

The camshaft was connected to the crank with a Cloyes double roller timing chain. It was buttoned up with a Cloyes aluminum timing chain cover; the timing chain cover has a built in cam button to eliminate cam walk and a removable plate to allow cam timing changes with out removing the timing chain cover.


Once the cam was degreed with 4 degrees of advance the Brodix Race Rite Oval port heads were installed.  We used the oval port heads to help with the low end torque and because we already had an oval port Edelbrock Air-Gap intake manifold. 



  Once the heads were installed the rocker arm geometry was checked, notice the witness line directly in the middle of the valve stem.

550 Horsepower 496 Big Block Chevy “Carb – Intake Manifold”

  To compliment the camshaft and new heads we installed an Edlebrock oval port air gap manifold. We already had a Demon 850 CFM speed demon carburetor, which worked well with this combination.



550 Horsepower 496 Big Block Chevy “Judgement day”

Not wanting to leave anything up to chance we bolted the 496 to the DTS engine dyno.  After the standard 20 minute break-in of the flat tappet camshaft we did a series of pulls optimizing the ignition timing and jetting.

549 Horsepower and 609 Ft-LB Torque all below 6000 RPM


With 550 + FT-LB of torque from 3000 to 5200 RPM this would make an excellent street engine, especially for a heavy car like a Chevelle or Impala.

550 Horsepower 383 Small Block Chevy

550 Horsepower pump gas 383 Small Block Chevy 

JMac Performance put together a 550 Horsepower pump gas 383 Small Block Chevy. Here are the details from the parts selection to the dyno testing.

550 Horsepower pump gas 383 Small Block Chevy “Parts selection”

I started the build with a good factory block; a 4 bolt main roller block out of a mid 90’s Chevy truck. The mid 90’s truck blocks have thicker castings, 1 piece rear main seal, and are fitted with hydraulic roller camshafts from the factory.

Knowing the 383 would be pushed to its performance limit I used all forged bottom end parts:

CP Bullet pistons, forged 3.75″ stroke crank, and 6.0″ forged connecting rods.


The key to making good horsepower is in the heads, camshaft, intake manifold, and carburetor. I used a set of Airwolf 220e’s, a Dr. J’s match ported single plane intake manifold, custom ground hydraulic roller camshaft from Iskendrian, and a 750 Mighty Demon carburetor.


550 Horsepower pump gas 383 Small Block Chevy “Block Prep”

 I had the block cleaned (hot tanked), bored and honed  .030 over w/torque plate, decked, and line honed. I installed new Durabond performance cam bearings. The performance cam bearings are a little harder that standard bearings so they can with stand higher loads brought on by higher valve spring PSI.   The block was thoroughly cleaned with soap and pressured hot water. All the bolt holes were cleaned with a thread chaser and the camshaft oil galley plugs were taped for allen head plugs.  


The bottom of the cylinders and the oil pan rail had to be clearanced to make room for the  3.75″ stroke crank and 6.0″ rods. The bottom of the cylinders were also chamfered to help reduce friction and piston skirt scuffing. 


To ensure maximum flow out of the oil pump I put a radius on the rear main cap oil hole.


550 Horsepower pump gas 383 Small Block Chevy “bottom end work”

To ensure the 383 will live a long and happy life I mocked up the bottom end and checked all the clearances.

I started with the main journals.  After having the crank polished I got 2.477″ on the main caps and 2.48″ on the crank giving us a solid .003″ clearance. I did the same with the connecting rods; 2.097″ on the rod ends and 2.100″ on the crank giving us the same .003″ clearance.


Next I checked the piston to cylinder wall clearance;  4.026″ on all the pistons, 4.0302″-4.0303″ on the cylinder walls giving us a little over .004″ piston to cylinder wall clearance. All the piston rings were hand filed to top -.019″, second – .023″ , oil ring – .015″ . 

Note:  To help reduce internal friction and free up a little extra Horsepower the CP Bullet pistons had a 1.5 mm, 1.5 mm, 3.0 mm ring pack.   


Before torquing everything in place I set the crank end play at .005″  


After all the clearances checked out I assembled everything together torquing the mains to 65 ft-lb. and the rods bolts to 63 ft-lb. Notice I used ARP bolts on both the rods and the main caps.  

Double checking the deck height we got -.005″ out of the hole.  This set us up with a quench of .036″ which helps reduce the chance of detonation on 91 octane fuel.  


550 Horsepower pump gas 383 Small Block Chevy “Oiling system”

 Leaving nothing to chance I always disassemble the oil pump (Mellings 55HV) and check all the clearances.  Notice the hardened oil pump shaft and welded on oil pump pick up. 

To help reduce windage and free up some more Horsepower I used a 6 qt. oil pan with a built in oil scraper and windage tray.  before bolting on the oil pan I set the oil pump pick to oil pan clearance to 3/8″.


550 Horsepower pump gas 383 Small Block Chevy “Valve Train”

At the heart of this 383 is a list of quality valve train components, starting with the custom Iskendian hydraulic roller camshaft. It is a single pattern camshaft with .595 lift,  244 degrees of duration @ .050 and an advertised duration of 290 all on a 110 lobe center. 

Because of the roller block the factory style hydralic roller lifters (I used Comp Cam lifters), guide plates, and holder were used in place of retro fit lifters.



 To take advantage of the free flowing heads I wanted as much lift as possible so I installed Harland Sharp1.6 ratio rocker arms.

Using custom length Comp Cam one piece push rods allowed for the proper rocker arm geometry.


550 Horsepower pump gas 383 Small Block Chevy “Completed”

 Here’s the completed engine waiting to be tested on the DTS dyno.

After completing a series of tuning pulls here’s a copy of the final numbers

 558 Horsepower @ 6300 – 510 ftlb @ 5000


Click on the links below to watch the this engine on the dyno

558 Horsepower – 510 LB-FT dyno pull

Idling on the dyno



Budget 350 build

Budget 350 build “The Beginning”

I decided it was time to rebuild the small block 350 that had been hiding in the corner of my garage for over 30 years.  It was originally purchased in 1978 as a project engine for my dad’s 1930 Model A coupe.  After some thought and a look at the raising gas prices he decided to stick with his very reliable, more economical 283.        Looking over the VIN number it was discovered our 350 was out of a 1971 Corvette (VO609CJK).  I was hoping to find some high performance parts (Steel crank and a 4 bolt main) underneath the 30+ years of grease and dust.  Unfortunately it was a 2 bolt main block,  stock cast iron crank and, slightly above average 3973487 casting heads.  Not what I had hoped for be still a solid foundation for a nice street engine.

Budget 350 build  “Bottom end work”  

 After the usual tear down and inspection it was determined the 350 needed some work.  It needed to be bore .030 over, the connecting rods needed to be resized, the block needed to be decked, the crank needed to be polished, and the mains were line honed .  Because the pistons needed to be replaced I decided to go with a slightly upgraded Keith Black hypereutectic piston and moly rings.     To top off the short block a new 8″ stock harmonic balancer was installed and the rotating assembly was balanced. With the exception of the pistons the bottom end was stock.  

Budget 350 build “A little head work”

looking over the cylinder heads they also needed some updating.  First thing I did was to have the heads decked about .020″.  (with the new pistons the compression ratio was now 9:1) Then I updated to new stainless steel ferrea’s (1.94″ intakes, 1.50″ exhaust) valves and had them cut with a 3 angle valve job.  To help with the low lift flow numbers I placed a 52 degree back cut on all the valves after the valve job was complete.    When the 487 heads were designed leaded fuel was the norm.  Knowing  this 350 would never see leaded fuel I had hardened valve seats installed on both intake and exhaust making them compatable with unleaded fuel.  The stock exhaust valve rotating retainers were removed and upgraded valve springs, steel retainers, and clip were installed.  To complete the cylinder head upgrade I gave them some pocket porting. I opened up the bowl about 1″ under the valve seat, reduced the valve guide, blended in the new hardened seats, opened up the complete exhaust port, and cleaned up the casting inside the intake port. 

Budget 350 build “Dyno testing”

To complete the build the 350 was bolted together using Fel Pro gaskets, a Mellings standard PSI and volume oil pump, 6 qt.oil pan, stock push rods and rocker arms, Edelbrock Performer RPM intake manifold, MSD street fire HEI distributor, and a Demon 625 carburetor. 

Performing the usual break-in and tuning on the DTS powermark dyno I was able to get the Budget 350 to pump out 356 Horsepower @ 5300 RPM and 386 lb-ft Torque @ 4300 RPM. Not bad considering this engine was rated at 270 Horsepower new from the factory. 











Budget 350 gets a 50 Horsepower tune-up

Budget 350 gets a 50 horsepower tune-up

Making 356 horsepower from the Budget 350 was acceptable for its original purpose, crusing to car shows in a 1930 Model-A Ford.  However, 1.0 horsepower per cubic inch isn’t exactly going to set the performance world on fire. There was definitely more power to be had so I set out to find it. 

Here’s what I did: 

  • Upgrade the rocker arms from stock pressed metal to full roller rocker arms with poly locks.


With the added pressure from the new rocker arms I needed to upgrade to a bolt in stud.  Not wanting to have the stud bosses machined I stopped by my local machine shop (Engine Supply in Santa Ana Ca.) for some help. They recommended a bolt in stud used as a direct replacement for the press-in type currently in the heads. All that I needed was a stud pulled, course thread tap that matched the studs, and of course 16 studs. The use of a  rocker stud removal/tap alignment tool from Comp Cams made the job easy.    




  • Upgrade the camshaft and lifters

I needed to add a little more lift and duration to fulling utilize the ported heads.  I happened to have a Comp Cams XE268H flat tappet cam on the shelf.

  • Increase the size of the carburetor

The last upgrade was increasing the size of the carburetor from a 575 Speed Demon to a 650 Speed Demon.


Budget 350 gets a 50 horsepower tune up “Dyno testing again”

After upgrading all the parts I took the Budget 350 back to the engine dyno.

Click on the link below to watch the engine on the dyno:

Budget 350 dyno pull


In order to get real world numbers  I used the Hooker Super Competition headers and the Magnaflow mufflers from the car it was going in, my 69 Chevelle.   


After setting the timing and re-jetting the carburetor the junkyard 350 made 403 horsepower @ 5700 and 426 ft-lb of Torque @ 4200.

Wanting to get all I could out of this combination I tested several carburetor spacers.


I found the 4 hole 2″ spacer made the best power curve .  It made 400 Horsepower @ 5700 and 430 ft-lb torque @ 3900.  Not a significant change at the peaks from the non-carb. spacer pulls, however the average torque numbers went up quite a bit from 2500 to 4500.  Knowing the car weighs 3500 lb. with the driver that extra torque was worth the loss of horsepower up top.

Here’s a copy of the graph with both dyno pulls.  You can see the difference in the  torque from 2500 to 4500.

Budget 350 gets a 50 horsepower tuneup “Testing in the real world”

After all the upgrading and dyno testing it was time to test the Budget 350 in the real world. I installed it  in the JMacPerformance 69 Chevelle.

A few details on the car:  4:56 gear, 28 x 12.5 x 15 Mickey Thompson ET street rear tires, Turbo 400 transmission, 2800 Stall converter, 6 point roll cage, 3500 lb. with driver. 








I ran it at the PSCA “Spring Break Super Show” held  March 11th – 13, 2011 @ Auto Club Dragway in Fontana Ca.  

It ran a best 12.486 @ 107.43 mph and the engine never went over 6000 RPM.  In fact the shift points were set at 5750 RPM.


The Budget 350 is a solid economical Street/Strip engine. It is a  good example of what can be achieved with good engine building techniques, focusing on the parts that make power (Camshaft, valve train, and heads), and putting together a combination of parts that work together.

600 Horsepower 468 Big Block Chevy Build

600 HP 468 Big Block

JMac Performance is building a 600 Horsepower street 468 Big Block Chevy engine.  As the build progresses I will cover all the details that goes into building a high quality street engine.

As our foundation we’ll be using a Gen V four bolt main 7.4L block

Pictured below are all the  parts that will go into our 468 build

SRP Pistons on Scat 6.385″ connecting rods with ARP bolts

At the heart of the engine is an Isky hydraulic roller cam and Cloyes double roller timing chain

A pair of Profiler 290cc aluminum cylinder heads will take care of the intake and exhaust flow

600 HP 468 Big Block “The beginning”

We start our build with a Gen V – 4 bolt main 7.4L (454) block. The block gets fully machined; Hot tanked, magged for cracks, line honed, bored .030 over, and decked to zero deck height


The extra casting (flash) is removed and all the threads are individually cleaned with a thread chaser.

 New cam bearings are installed

After boring and honing the cylinders they are chamfered on the top and bottom. (The top to help with the piston and ring installation, the bottom to reduce internal friction and eliminate scuffing of the piston skirts)


600 HP 468 Big Block “Checking bottom end clearances”

 To insure our 468 will live a long and happy life we need to check all the clearances of the bottom end.  We started out by cleaning and deburring all the bearings.  This is a step most engine builders delete. I like to verify the quality of the bearing finish and insure they are burr free before installation.

I  installed the main caps and the bearings then torque them to spec.  In this case 100 ft-lb.  (Note: For added insurance we replaced the stock main bolts with ARP bolts.)

 I used the micrometer to verify the crank main journals (2.748″)  then I used the bore gauge on the main bearings (2.751″) to get our (.003″) bearing clearance.

I did the same with the rod journals (2.194″),  torqued the ARP rod bolts to 63 ft-lb, I used the bore gauge to verify the connecting rod bearings (2.219″)  to get our (.0025″) bearing clearance.  (Note: The use of the rod vise when torquring down the rod bolts)

The first set of rod bearings yielded a (.003″) clearance, a little too wide for our application. The wider rod bearing clearnace would have resulted in lower oil pressure. After installing a slightly under sized bearing we got our (.0025″) clearance.



Once the bearing clearances were verifyed I installed the crank and checked the end play.  It was a little tight (.003″)  with a few taps of the rubber mallet got me (.006″) end play.

600 HP 468 Big Block  “Bottom end installed”

 I used the micrometer to check the Forged SRP piston diameter (4.277″)

then I checked the cylinder diameter with a bore gauge (4.281″) subtracting the two and we get (.004″) piston to cylinder wall clearance.

To insure proper cylinder sealing and minimize oil consumption the ring end gap needs to be set.  I used a set of Total Seal file fit rings which are (.005″) larger than the bore diameter. This allows the builder to cut the rings to the exact size for each cylinder.  The ring manufacturer calls for a  (.019″) top ring and (.016″) second ring end gap.  Each ring is hand filed and fitted to its specific cylinder.


The pistons are installed and I check the deck height (.000″)


After the pistons and rods are torqued down the rod side clearance is checked (.023″ – .024″)

600 HP 468 Big Block “Camshaft and oiling system installed”

I  buttom up the lower end with the installation and degreeing of the camshaft. I’m using Isky hydraulic roller cam 396282/294. After adjusting the crank sprocket the final resting position for the camshaft is +3 degrees advanced


Unlike flat tappet camshafts roller cams rely on backing plates or cam buttons to limit camshaft movment.  I installed a timing chain with a Torrington bearing to help minimize the internal friction between the timing chain and the block.  Because after market Gen V Big Block timing chain covers are hard to come by I  modified the existing timing chain cover.  I welded on an additional plate to stiffen up the cover.  By doing so I was able to get the proper camshaft end play of (.005″)


Oil control is key to freeing up extra Horsepower so I installed a Moroso 7 Qt. pan and a oil scraper.


The oil pump pickup to the bottom of the oil pan clearance was checked (3/8″) and the oil pump pickup was tack welded to the pump for added protection.


600 HP 468 Big Block “Heads, valve train, and induction system installed”

Before bolting on the heads and valve train I needed to verify the valve to piston clearance.  I placed small chunks of modelling clay in the valve reliefs.

The head gaskets were installed and the heads bolted in place

The rocker arms, lifters, and push rods were installed (Note: because the push rod length was not known at this time I used two adjustable push rods) The engine was rotated two full cycles, the heads were removed, and the clay was inspected.

Piston to valve clearance on the intake (.220″) and exhaust (.200″). More than enough for our application

The valve train geometry and push rod length was verified. I marked the valve tip with a sharpie pen, install the valve train and rotated the engine one full cycle. This process was repeated until I got the witness marks in the middle of the valve tip.

The push rods lengths ended up at (7.650″ and 8.650″) and a set of Manley push rods were ordered

The heads were bolted on, the Isky hydraulic roller lifters, Manley push rods, and Crane rocker arms were installed.

The build was finished off with the  installation of an Edelbrock Performer RPM Air-Gap intake manifold, Speed Demon 850 CFM double pumper carburetor, and MSD billet distributor





600 HP 468 Big Block  “Dyno Testing – Judgement Day”

To insure we got all the performance out of our 468 build it was run on a DTS Powermark engine dyno at Saddleback Community College in Mission Viejo Calif.

I did an  intial 15 minute break-in then a few short pulls to verfy timing and set the air/fuel ratio.  After a quick cold down period we let the 468 go pulling it to 6500 RPM

624 Horsepower – 590 lb-ft Torque,  on 91 Octane pump gas.

Click here to view the JMac Performance built 468 on the dyno



This engine is a great example of what can be done when the proper parts are used, the proper engine building techniques are implemented, and nothing is left to chance.

Contact if you’d like more details on this engine build.