Originally Posted by 90caprice408
I recently built a sbc 408 for my chevy caprice but for some reason it seems to have no bottom end grunt....this is the cam i used for my build Lunati Hydraulic Flat Tappet Camshafts 10120412 - SummitRacing.com
....i used flat top pistons and 64 cc aluminum heads so my compression is around 11:1..i'm running a 3k stall converter with 3:73 gears th350 and a 750cfm carb and air gap intake...I have my timing set at 16 base and 32 total...My question is can anybody point me in the direction as to why this setup has such a lazy low end? it is also my first build so take it easy on me
It's a shame you didn't ask about this combo before you built it! Not ragging on you- just saying.
The best thing to do would be change either the pistons to a d-shaped dish or swap to a larger combustion chambered head, along w/swapping out the cam for something designed to make good low end torque. But if that's not happening, you are going to be saddled w/a camshaft that cannot give the kind of bottom end torque the car would really like to have (big, heavy car = big torque, not necessarily big HP), along w/not being able to give it max power total timing, AND still needing premium gas, possibly mixing in some race gas.
This is one time I will agree to give it a ton of initial timing, even if that means locking the mechanical advance. You can still use (and should
use) a vacuum advance. Hook it to ported
vacuum if you lock the mechanical advance. Limit the vacuum advance to around 10-12 degrees.
More on locking the mechanical advance, setting up a vacuum advance, wiring an ignition interrupter switch, and timing info in general is here