Hot Rods Edelbrock 650 thunder AVS on 273 mopar ?

I've used the carb calculators and know the 650 Edelbrock thunder AVS that I have is to LARGE for my dodge 273. This carb is left over for another build.
The caluclators come up with 380-475 CFM @ 5500. I've got the smallest Summit cam, Electronic Ignition& adjustable vacuum advance. Edelbrock performer intake, dual exhaust (not headers).
Can the 650 thunder AVS work well on my 273, if I rejet/and rods ? I never run hard, just cruise. I'm always looking for better MPG. Or will I be better of buying the Edelbrock 500 thunder AVS ???

 

Get a Holley 350 2-bbl.

 

My comb is setup for an edelbrock carb, all my linkage,etc. So not going to rework everything.

 

anyone had any luck using a 650 on a small V8 ?

 

You can get a simple adapter.

 

I would go by the advice that every carb builder, Edelbrock, Holly etc. puts out. Personally I think a 650 CFM carb is quite big for a 273. Reminds me that when we were kids we put dual quads on a 283 Chevy and it ran slower. It ran great with one four barrel so it should run faster with two, not so.

 

The front-half of that 650 is 95% of what that engine needs, at redline.

If you must run a 4-barrel, get a vacuum secondary 390, 450, or 500.

 

Gm ran 750 quadrajets on 305s , Ford ran 600's holleys on 283's and 302's , a carb will only pull what it needs , you might not open the secondarys but with a high vacum number or some weight tuning they might open , you definately will have to rejet it down as it might run rich .

 

Yeah I know that the 650 AVS will self regulate. But I'm thinking that even if I do jet it down, that the 500AVS would be a much better choice.

 

If those are your options, get the 500.

 

500 would be more responsive when you kick it to pass some one . do not forget holley still makes the 390 -4 barrel vacuum secondaries . that would fit the bill perfectly as it would keep the intake velocity up .

 

Thanks guys for your input.

 

Remember, "jetting down" just leans out the mixture. It does nothing for venturi size, or throttle plate size.

Ideally, you want the highest possible velocity through the venturis that can be achieved, without causing a restriction.

Remember, the vacuum produced is what draws fuel through those jets. Decrease the velocity too much, by having an air pathway that is too large, you lose the vacuum signal.

Do that, and the carburetor will simply not meter or deliver fuel properly, regardless of what the size the jets are.

You really do need a 390, or 400, or even a 2-barrel.

 

We would recommend the Holley 390 for the 273. We have a stock running 318 and a stock running 360 that we put the 390 on. The 318 was running a 600 Edelbrock and the 360 had a 500 Edelbrock. Couldn't make either one run right. Ran way too rich and dumped gas into the crank cases. Did everything Edelbrock said to do and more but was never right.

Both vehicles run way better and perform so much nicer you would think it was a different car. The 390 has been an almost spot on setup for the 360 and for the 318 it could stand downsizing the jets a size or two. If you need a manual choke setup All State Carburetor sells one online on their website and they also have the Holley adapter/extension piece for your Mopar linkage.