Carburetors - which one?

[coolcvi 11]

I have a 302 from a 1998 doner car. The old carb is in need of replacement. Thinking about a Holly, but the choices are confussing. Engine is bored .030 over, mild cam, Torker 4 barrel intake manifold, going to be for street usse, T-5 manual transmission. Thanks, Dan

[Max Power 74]

If you have stock heads, you don't need that Torker and a 600 Holley would be plenty.

[jholmes217 65]

I'd go with a 570 cfm Holley Street Avenger, A Summit 600 cfm, an Edelbrock 600 cfm, or a Holley 600 cfm, all vacuum secondary, or a Autolite 4100. With that mild of a motor, I wouldn't go over 600 cfm.

[LoneWolf2U 136]

Run a Summit 600 vs its a plug and drive carb.

[juit 34]

for street later motorcraft 2150 models with the high-speed air bleeds

[therebel 10]

I've had good luck with Holley double pumpers from mild to wild engines.

[buening 63]

Run a Summit 600 vs its a plug and drive carb.

 

+1. Good carb

[bomccorkle 12]

A smaller demon would give room to grow.

[wilcoxfe 10]

Ok, so I went with the Holly street avenger 650 cfm. I'm wondering if I messed up and should have gone with the smaller carb (like the 570). Would it be worth my while to stick with the one I've got, or should I consider trading it out? What kind of performance would I notice?

[SA69mach 39]

The 570 Street Avenger is a very good fit to the 302. Vacuum secondary and electric choke. The 650 or 670 SA you have is a little oversize. You will be wasting fuel and will not get the same crisp response off the line with too big a carburetor.

A nice set up would be the 570 SA on the dual plane Performer RPM. One inch phenolic spacer will give you improved velocity and increased plenum size, which works with a smaller carb very well in a 302.

Ideally you would want a matched cam, but the three items listed above will give you a nice improvement and good response to 5500 rpm.

[wilcoxfe 10]

The 570 Street Avenger is a very good fit to the 302. Vacuum secondary and electric choke. The 650 or 670 SA you have is a little oversize. You will be wasting fuel and will not get the same crisp response off the line with too big a carburetor.

A nice set up would be the 570 SA on the dual plane Performer RPM. One inch phenolic spacer will give you improved velocity and increased plenum size, which works with a smaller carb very well in a 302.

Ideally you would want a matched cam, but the three items listed above will give you a nice improvement and good response to 5500 rpm.

 

Thanks SA69mach,

I should have mentioned, I have a 351W bored out to .0003. I have a thumper cam. It took some tweaking, but we got the carb (Holly Street Avenger 650 cfm) finally set. The car has pretty quick response - yet I've heard a couple guys mention that the carb is oversized. With that said, Would I notice a big difference by going to a smaller carb?

[SA69mach 39]

a 650 Holley is nicely matched to a 351W. I thought you had a 302 roller from a 1998.

A 30 thou over 351W with a thumper cam. Do you have more information, like compression ratio, is it hydraulic flat tapped, or roller engine. Intake? Heads? I am not sure if this is the same engine package from your first post.

 

In very general terms, smaller carbs with a taller intake height will provide faster flow velocities and will give improved low rev response (all things being tuned right - like timing etc).

But you will reach a point with a undersized carburetor in its capacity to provide fuel at high revs.

The 650 is considered by many to be too big for a stock 302 engine. I happen to agree, but that doesn't make it true for all applications. Cars are used for lots of different purposes. For street use on a fairly stock 351 Windsor the 650 Holley is a good match.

No you would not notice a big difference by going a bit smaller. 390 cfm would be as small as I would even consider on that engine and you will definitely notice it. 570 Street Avenger - hardly notice until 5200-5500.

 

spacers have 2 advantages. they insulate the carb from engine heat, and they add height to the stack, increasing air/fuel velocity.

 

If you have a Street Avenger, it is a 670 cfm, not 650.