tomngary

Mild build on the 403 with rebuilt #6 350 heads, new aluminum 3711 intake
carb rebuild, headers with dual exhaust, new 2200 - 2400 torque converter,
3:08 rear gear already installed.
350 heads will not have rollers due to expense.
My local speed shop recomended these specs for my cam:
Comp cams dual energy cam and lifters
219/233 duration @ .050
476/508 lift
110 degree centerline

Cam selection is rather greek to me so I am trusting the local well known
speedshop for guidance. Is this cam ok to use?

Thanks guys,
gary

cutlassefi

I'd like to think I know a thing or two about cams, and I actually like some of the Comp Dual Energy cams. That's what that is.
But that one is wrong for your application. The reasons are you have done more on the exhaust side to improve flow than on the intake side. Therefore you don't need or want that much split between the two. Plus you have a tall gear, so you'll benefit from more low end torque which a different style of cam will provide. And when you have that much more exhaust duration vs intake that lends itself to higher rpms. Are you really going to spin it past 5500? And how often?

I'd do either a single pattern around 220@.050 or one with a smaller split between the two, maybe 4 or 5 degrees max.

Kennybill

You don't say anything about overbore or new pistons. I will give you my opinion based on stock cast pistons. Yes, keep it under 5500, plus with the 3:08 gears & stock rockers & bridges, better to be under cammed. I like the comp's cam H268, .456/.456. I've have used this cam in 3 engines, presently in my 71 Royale 455. TRW had a .456/.472 cam, may work. I wouldn't go any higher. Jmo. You'll be surprised how that .456/.456 wakes up that engine. It's an RV/torque cam just what a mild/street 403 needs. Good luck, Ken

tomngary

Thanks for tips on this, the general consensus is that the split between exhaust and intake is too big for a low rmp torque motor? The speed shop I'm using doesnt work with many oldsmobile motors I'm thinkin.

Thanks again,
Gary

cutlassefi

Let me know if I can help. Thanks and best of luck.

DeltaPace77

My car originally had a stock 403 I warmed over with a dual pattern custom Crane grind I got from H-O Enterprises that ran pretty good. Specs were 222/232 duration @ .050" and .495/.520 lift 110 centerline. Had to change out the valve springs and pushrod length, but no big deal. Also used Crane Hi Intensity lifters, that bleed down a bit at lower rpm. Also use these lifters on my current 455, and really like these on the street.