Quote:
Originally Posted by Masaki
Haven’t checked the codes but. It is posi and once ran its original intake with original 4bbl carb(now changed to a ported dual plane p4b intake and 600cfm E-choke Edelbrock Carb) I’m also looking to revamp this setup for more power. Any tips? I’m currently making around 320hp
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Sounds like it could be a 350HO if it had a factory 4-bbl intake and Q-jet carb, plus having a Safe-T-Track (posi in Pontiac-speak) are good signs. If your car is an HO car (and has the original rear end) it should have 3.55 gears, more than good enough to support more performance goals in the future. Confirm you have #48 heads, then it’s just a matter of choosing the right cam. In most applications with an automatic trans and stock style (low stall) convertor, you want to keep the cam timing conservative like the factory 067 cam (197/213/113 @ .407”/.407” lift) or the Summit 2800 (204/214/112 @ .422”/.444” lift) and equivalents. With a looser convertor (higher stall), you could use the factory 068 (212/226/116 @ .407/.407” lift) or the Summit 2801 (214/224/112 @ .444”/.466” lift). New valve springs to support the lift/rpm range of the cam you choose needs to be selected. With lifts higher than .450”, you need to check for valve to block interference (at the cylinder bore) between the intake valve head and cylinder bore (which should have scallops/chamfers at the deck surface). Don’t go crazy with big cam timing.
If you are rebuilding the short block, go with a lighter reciprocating assembly with Eagle H-beam rods and lighter forged pistons with the 1/16” - 1/16” - 3/16” ring packs. Have the block decked to zero and use the Felpro 1016 head gaskets for .040” quench. Use Ram Air exhaust manifolds or 4-tube headers (1 ¾” tubes) with a good 2 1/2” mandrel bent exhaust system (Pypes) with DynoMax UltraFlo’s or MagnaFlo mufflers. This should get you in the 340 – 350 hp range and keep your Lemans very drivable.
Dennis