4bbl, better mileage?

[tjcustomranger]

i found somebody will to trade some parts i need for my truck, like front clip, seat, and a rebuilt 4bbl with intake off of a 390. i was told by a couple people that it would give my 360 better mileage with the 4bbl but others say it would drop mileage even more. would a 4bbl help any? if not i'll go for the 205 transfer case instead

 

[jebadiah04]

If its spread bore, it will. Square bores can if they are small enough

Sent from my mudwhistle via Lemmiwinks.

 

[tjcustomranger]

what do you mean, spread?

 

[BuzzGun79]

There are things to consider to get the mileage out of 4brl carbs...yes they do give better "volumetric effiency" than a 2brl,when the right carb is chosen.
cfm also comes into play...the higher the cfm,naturaly the more gas it will use.for a stock 360,I would suggest staying in the 500 to 650 cfm range at most IMHO Through my own experiences. anything above 650 is overkill you dont need it imo.
keep in mind the carb must be in excellant working order to acheive good numbers,stay away from the double pumpers if you want mileage,their not desigened for that.ive found in time that single an dual feed carbs give the best mileage,also keeping the right foot out of those secondaries helps a great deal......if you can..

 

[jebadiah04]

Spread bores have small primaries and HUGE secondaries. Great power, great economy. Very common in chevys

Sent from my mudwhistle via Lemmiwinks.

 

[m78]

My problem with 4bbl is I couldn't keep my foot out of it.
And that opens up those huge secondaries.

 

[jebadiah04]

Yep...my 454 rarely gets out of the secondaries, but im also running 8" lift and 38s...its like wind resistance hell. Lol

Sent from my mudwhistle via Lemmiwinks.

 

[tjcustomranger]

its 600 cfm. he said he rebuilt it and then his truck broke down but he drained all the gas out of everything. he said a valve or something broke and ruined the engine. but the carb and intake are good as well as the few other little things i need. but if that 4bbl will help my truck i would love to get it.
i think it might be a motorcraft. i don't have issues with them last truck had one thats what my dad runs too

 

[jebadiah04]

600 should be good on a 360

Sent from my mudwhistle via Lemmiwinks.

 

[tjcustomranger]

he is suppose to get me some pictures of it today, i'll post them when i get them.

 

[jebadiah04]

I had a motorcraft on my 300 i think...maybe it was a carter. It lasted 16 years before i had to rebuild it...i believe it was a carter "y" now that i think about but it had a motorcraft tag. If its a carter, they are the same as a edelbrock for the most part.

Sent from my mudwhistle via Lemmiwinks.

 

[tjcustomranger]

i think its motrcraft. didn't get pictures of the carb r intake but did get some of the seat and core support

 

[tjcustomranger]

the carb looks like a 2bbl 2100 motorcraft. looks nothing like a 4 bbl

 

[jebadiah04]

Its a 4bbl im 99.67% sure of it.

Sent from my mudwhistle via Lemmiwinks.

 

[jebadiah04]

Cant tell if its square or spread bore though.

Sent from my mudwhistle via Lemmiwinks.

 

[jebadiah04]

Tell him u need top down pics, or pics of the bottom of it, unless you are buying the intake too, then it doesnt matter

Sent from my mudwhistle via Lemmiwinks.

 

[tjcustomranger]

If its 4bbl and hopefully spread bore I will. I have another guy with parts and he has a Holley 4bbl. What are the odds of it being spread?

 

[jebadiah04]

Rare. Spread bores arent super common, but you need a spread bore intake if you go that route. They are different. You rarely see spread bore after markets.

If i had a carbed dd id try to find a spread bore intake, then get agood NEW not used rochester quadrajet to go on it that would be used for a chevy 350. They have small primaries but the secondaries a HUGE on qjets, giving you nice mileage and mean power under gull throttle. Plus gm usually put way bigger carbs than required, but that's because the way the qjets are designed they atomize fuel well and run on low cfms cruising. The emulsion tubes on them are pretty cool. Qjets are tough to beat, but they are usually so wore out and have been rebuilt using jamaican parts so many times they are unrepairable. I still have one, but its fd over bad from previous owner of my blazer. If you do by a used qjet make sure you hear it run first

Sent from my mudwhistle via Lemmiwinks.

 

[BuzzGun79]

you may want to checkout the Holley 4160 series...these are a performer carb,but an oe upgrade....i run one on my 460 and im quite pleased with its performance and fuel mileage...a good bang for the buck as well as it wont brake the bank.priced around $280.00 and can be upgraded as well.

 

[1970Custom]

Best bet is to NOT buy a used one, Tater....

Just sayin'....