Cool a 400M is much better! Part of why you're soooooo slow is your gearing, but ya prolly know that already.Originally posted by JayBo@Sep 15 2004, 07:11 AM
After looking (and cleaning) the engine bay some, I found a sticker on the valve cover that states the engine is "351M/400 Family" and that the size is 400CID, so I'm assuming that it is a 400 now..the dude I bought it from musta not known what the hell it had. It has the factory 2bbl on it, so I"m sure it would benefit from a carb upgrade, and maybe some headers.
Also, what kinda wheels you got for it? I don't want anything fancy, I bought mainly for playing and not tearing my Chevy to pieces.![]()
Anyway, you have the 2bbl heads...that's GOOD. Their ports are much smaller and street friendly...the valves are still absurdly large as are the ports. A good street intake like Edelbrock's Performer would be fine for it, it's a big heavy truck so you need low to mid range TQ/HP.
I don't think I'd get an off the shelf cam, I'd call Comp or Crane and see what they'd recommend for you. Probably something with so-so lift, short duration (about 208-214), and not much overlap.
Headers with 1.625-1.75" primary tubes are plenty large, smaller tubes lower the TQ peak; conversely larger tubes raise the peak.
A 650cfm 4bbl is plenty large for that 400" as long as you stay south of 6000rpm.