318 or 360, 727 or 904

[volaredon]

I wouldn't do an adapter. If you want to run the 2 bbl as the 360s did simply swap to a 360 intake. I've do e that before on an otherwise stone stock 318. Problem is that particular Holley is "feast or famine"... If you get a good one it's really good, otherwise they're crap. I've rebuilt my share of those carbs, not hard at all.
Skip the adapter if for no other reason than being so much easier to deal with the trans kickdown linkage, with an adapter you raise the carb which puts everything out of sorts and creates problem of it's own. That and trying to choke the mixture from a bigger carb they a smaller plenum doesn't give as good of results either than being directly bolted to a manifold flange that's sized for it

 

[413]

If you want to use the larger 360 carb the you can use a 360-2bbl intake on your 318. No need for an adapter.

Plenty of guys building 360's will be tossing the 2 bbl intake.

 

[fury fan]

But don't all 360 intakes have larger runners/ports than the 318 heads?
I guess you'll have a pinching turbulence point regardless, whether at the carb adapter or at the heads.
I would think the carb adapter might be a smoother transition, though?

 

[CBODY67]

All the carb adapter does is mount the higher-cfm carb to the small throttle plate hole manifold. Ultimate air flow will be the same due to the smaller holes.

 

[fury fan]

But a carb adapter will give a bit of a transition, while a larger intake port into a smaller cyl-head port gives a sharp wall to the airflow around the perimeter of the port.

 

[413]

But don't all 360 intakes have larger runners/ports than the 318 heads?

Do they? I'm not sure. Thought that was only on a 340 engine.

 

[fury fan]

The 360-4 intakes, which they used on 318 4-barrels (which used 360 heads), all have larger ports into the heads.
I don't recall any small-runner LA318-4 intakes except for the Streetmaster (Holley?).
All the later OEM 318 4-V intakes were configured for a spreadbore (Thermoquad and then Quadrajet) and for 360 ports.