The 383 in the JMacPerformance 69 Chevelle is getting upgraded
- Increased compression from 12.2/1 to 13.7/1
- Cylinder heads are getting custom porting, angle milled, and larger intake valves from Mamomotorsports
- Fully ported intake manifold
- Larger custom solid roller camshaft
- Engine dyno tuning
Details in the next few weeks
