I have a 351w freshly built with a 268 cam, bores .30 over and an edlebrock preformer intake in a 74 ford bronco automatic. I stay on the Hwy. most of the time but am not afraid of the mud. I need a new carb. the 4180 I have which came on the engine almost killed me the other day when it hung open!!!

What carb do I need and what CFM? I also want and electric choke.
thanks!

 

Formula says a 600 cfm would be fine, I would recommend vacuum secondaries. I like Holleys, but an Edelbrock Performer carb would work well. Holley List 80457 with the Ford AT linkage would work.

 

A 600 or 650 would work fine. You can go with a Holley truck avenger or an Edelbrock 600.

 

what about a 670 truck avenger????

 

ALSO, IS THE TRUCK AVENGER WORTH THE EXTRA 150 OVER THE 600 Holley List 80457 ?

 

I would run a 600 Edelbrock if you don't do serious off roading and if you do than i would go with the truck avenger 670, although you will need to tune it down a little to get mileage out of it. The truck avenger costs more because it is designed to work at a steeper angle without flooding the engine. If you run mostly flat to moderate hills than you will never see the benefit of the avenger and you will just be wasting money. The regular Holly will also work well, it just is personal preference as to which one you want. The eldelbrock is a little more beginner friendly, but with a little practice either one is easy to tune.

 

The 670cfm would be way too big!

Over-carbureting an engine is the most common mistake most people make when building up their engines. When you over-carburete an engine, it will hurt your gas mileage, pollute the air more, and it won't reach its potential until you get into higher rpms.

351 X 5,000 RPM / 3456 = 507cfm
...and that calculation is based on 100% volumetric efficiency. Stock engines typically run at 70-75% volumetric efficiency. "Race" engines typically run at 90% VE.

In other words, YES, you COULD use the 650cfm, but it will be harder to tune, it won't idle as well as a smaller carb, and it won't run right at lower RPMs because that a 650cfm is good for 6400RPM. BE REALISTIC. Are you going to RACE your truck? Will your truck REALLY run up to 6400RPMs? When you over-carburete, you are only hurting the end result.

For street use, 600cfm at the most. The Holley 570cfm Street Avenger would be a great choice.

 

Is 600 too much? I found a refurb on Ebay for 179.00!

 

Run the 600 it will work good with just a little tuning and it will give you room to upgrade in the future.

 

I bought a 600 holley form national carburators in fla. it cost me 175.00 plus 20.00 shipping. Better than the zone which was 259.00 plus tax. what upgrades latter??

 

Also what should she idle at cold and warm???? what rpm should it kick down???

 

Warm, about 650 in gear, cold about 1100 to 1200 for a few minutes until you bump the throttle.

 

Thanks guys! You have been great help!

 

awesome thread, i had the same questions myself!!!

 

Guys just a little update. i put a holley 600 on it and she runs perfect. will turn over my p buckshots. I bouthg a space but to make it fit, i will hove to drill the threaded holes out and the space is aluminum. where can I get a good spacer that will work on a edlebrock performer intake and a holley 600??