Holley 6853 0 4165 Competition replacement for all Quadra-Jet carbs. on 1965-70327, 350, 402 C.I.D. engs. Mechanical secondaries, spread bore,double pump, 650 c.f.m., non emission, divorced choke

It would go in a 79 vette with 355/th350 auto. 355:1 gears w/ stock tire size. Dart 200cc/72cc/2.02 heads, Comp Cam 276 magnum, full length headders and duels, weiand action plus intake and 2200 stall (somday).

Would this carb work ok for me or would the double pumper and mechanical secondarys kill me with the automatic? Thanks for the input.

 

You should probably go with a vac sec carb, but thats not the big strike against it. I don't liek those Qjet replacment holleys. Go for a normal squarebore Holley.

 

I am kind stuck with the spread bore setup because of my intake and nitrous plate. I have 2 factory quadrajets I am kicking around rebuilding and using. What is a good spread bore for my setup?

 

Don't use a carb calibrated specifically for a big block on a small block. Use the 6210 instead. It's very similar except even less emissions considerations. I've used at least 10 of those, plus a couple of 6211s (its 800 CFM big brother) on various cars over the years, I think it's the overall most versatile carb of its type.

Big block carb on small block = very rich at idle and transition, lean the rest of the time. Think about it: idle fuel is delivered based on vacuum; if you have 2 engines with the same vacuum but one twice as large as the other, it will need twice as much gasoline at idle; the smaller motor will drown in that much fuel. On the other hand, at any given load, the smaller motor is closer to WOT and more in need of enrichment than the larger, so it needs more fuel per air molecule.