Originally Posted by maddart
I will be rebuilding my 350 which is my first build and looking to produce about 425hp.
I'm starting with a 1996 .030 over block, forged scat rods, scat crank, speed pro pistons 10.1cr using pro comp aluminum angle plug heads 64cc 2.02 intake/1.60 exhaust. 1.6 roller rockers with girdles.
Current cam is LT4 Hot Cam duration at .050" tappet lift (intake/exhaust) is 218/228; and maximum lift with 1.6 rocker ratio (intake/exhaust) is 525/525. Roller lifters, Summit dual plane intake.
While i have the motor apart i think i would be better served with a bit more radical cam, looking for recommendations/part numbers, I'm assuming i have to change out the valve springs also.
TH350- 2600 stall
Rear gears-3.42 posi (Possible future upgrade to 3.73
Rear tires- 275/60/15
What you have with an Edlebrock Performer RPM intake or a Victor Jr with a 750 Holley or Holley clone in place of the Summit intake and 625 CFM carb should go to an easy 425 on an engine dyno. I'd keep a half set if 1.5 roller rockers in my tool box, often on these split intake to exhaust duration cams the use of 1.5's on the exhaust has the effect of bringing the power band down a few hundred RPM with no sacrifice in the top end power. just widens the peak curve over more RPMs. So this is a useful tuning item as are carb spacers.
The Comps are an OK head especially the latest go around. They like a lot of lift on the intake. They also respond to a back cut of 30 degrees on both the intake and exhaust valves more than most other heads, this will pick up the Comp's rather weaker mid lift flow as well.
Valve springs should be a decent quality beehive. These things really keep the valves under control without having to go to exceptionally stiff springs.
Other than that this should be good to go where you want.