Monthly Archives: December 2010

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.