318 Compression ratio
Supposedly smaller ports are good for torque.
There are several other things that figure into this, such as valve size and valve lift/duration. Typically smaller ports maintain flow velocity at a higher level if all else is equal.
You think a ThermoQuad would work in this setup? Or should I stick with a 600 or a 650 carb?
Depends on where the cam comes on. If it is a higher rpm type of cam, then the Thermoquad ought to work, especially with a slushbox.
For your consideration:
The high compression 273 HP used a 625 AFB.
The 340 used the AVS and Thermoquad (don't have cfm ratings handy).
The low compression 318-4 cop car motor used a Quadrajet.
In fairness, the de-smogging of each engine is progressively more stringent.
The 67-70 318 stock pistons come closest to the deck. Summit will sub them into a later model kit if requested at no extra charge.
My Demon has a warmed up 318. Engine block is 68 318 with a 73 front cover and balancer. Block deck & heads lightly planed for good seal (less than .010 removed from each). With the heads, pistons, and gaskets used, I've calculated a 9.38:1 compression ratio. It has cleaned up 302 heads and a Crane hydraulic cam 218/228 @ .050 lift. The top end consists of a Performer intake with a 625 cfm AFB. IMO it's a stout street motor with good throttle response. It wakes up around 2000 rpm which works for me.
