383 chevy cam choice etc

Gidday, I told my mate how helpful you guys were with me planning my engine, and he is in a similar position to i was but with a 383 and not a 350 so i said I'll try on here and see if i can get some advice for him. He is building a 1963 Pontiac laurentian (probably about 4500lbs). His diff is standard low 3's and will be placing a 3.7 or 3.9. Th350 with ??? stall
383, 400 crank turned down, hyper pistons 2 valve relief (supposed to be 10.2 with 64cc heads), has victor junior manifold with 750 dp holley, pro topline heads as cast, with 220 cc runners 64cc chambers and 2.02/1.6 valves with 1.6 rockers. he'll be onlly using 2 1/2inch ramshorn style exhaust manifold, but needs help choosing a cam. Every book he reads says 383's respond better to a small cam, but his top end is quite big and was thinking a big cam with antipump lifters. Any ideas of what will get this big tank up and moving, it has to be streetable but also wants street/strip supremacy. I personally told him like yous told me, rpm manifold with 200cc runner heads with a nice torquey cam but he has already spent the bucks and now just requires cam, stall and gearing to be finished. he also needs to know if he needs to use longer/shorter pushrods with the heads as they have .100 longer valves. Thanks and hopefully someone may be of assistance. Any idea of power range this would produce 300-350 350-400?


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With those specs his compression ratio will be more like 10.5-10.6Cr. You're right about the intake & heads, Eddy RPM & 190-200cc would be better.
You'll need some rear gear & stall to get all that weight moving.
Look a Comp's Magnum Grind#286H/Part#12-326-4 or ExtremeEnergy XE284H/12-250-3 with 3000-3500rpm stall.
Those heads are not the best for low rpm torque on a 383 tho.' May as well use the rpms.
I'd use a Vacuum secondary carb also. 3.90 gear.
4.03" Bore X 3.75" Stroke, 64cc Head, 2VR Pistons-4cc, .025" Deck Ht., .041" Head Gasket, .066"Quench = 10.58Cr
Same with 4VR Pistons-7cc = 10.25Cr
Same with 0 Deck Ht., KB197 Pistons 12cc D-Dish, .041 Quench = 10.27Cr

If the car weights more than 4000#s use a 4.30 or 4.56:1 gear.
You'll need a 3500stall at minimum. The above cams will work well with that.
The exhaust manifolds are really really going to kill it. Get some long tube headers.
I believe "63 era SBC Impala/Biscayne headers will fit the Canuck Pontiac car.
With the big heads and single plane manifold, the motor is going to want to rev. Don't wimp out on the gears or converter stall if you want it to work well at the strip. It's a heavy car.

The exhaust manifolds make it tough. I like the comp cams 280/290 XFI flat tappet hydraulic grind. With the 1.6 rockers the lift will be .552/.547. The duration is 236/241 and it is ground on a 113 lsa. The wider lsa will help with the manifolds.

thanks guys. i will pass on all those cam numbers and stuff to him. reason why he was using the 2 1/2 ramshorns is there is nothing available over here, hardly any impala's or similar. costs big money for custom made ones. same with the diff, he was hoping to keep the standard ten bolt (yes i know) and use a earlier diff head 3.7/3.9 as it will costs few thousand to make up a 9", so either he'll have to spend the money on the diff or rebuy new heads and manifold.. but the setup should be plenty of power anyway by the sounds of it..

If you're going to stay with a moderate gear ratio, then change the intake manifold.