Difference in carbs

[st3vomettler]

What is the difference between a 77 c10 350 carb and a 86 c10 305 carb?

[enaberif]

stock? aftermarket? if a quadrajet get the model numbers.

[LTZ C20]

If stock, 77 carb has vacuum secondaries, electric choke most likely. An 86 is computer controlled, electric choke, possible california emissions. Just to name a few.

[st3vomettler]

I replaced the 77 carb with a autolite carb from autozone when I have the 350 in my truck but it has a stock intake

[st3vomettler]

And my carb is Manuel choke

[LTZ C20]

Ok. You have a 350 and you put a replacement carb from auto zone on it? Why did you replace it, what was wrong with the 77 carb?

[st3vomettler]

When I get the truck the guy put a new carb from autozone on it and it was sucking air at the front base so I took it back and exchanged it but I don't now hat was wrong with old the old carb and when the motor blew I got a 86 305 to put in it so I could drive it and that motor didn't have a carb so I'm using the old carb of the 350

[blazer74]

77 carb probably was  the old style 4mv with divorced choke, they were used to about 78 on trucks.  Most carbs around 86 are M4ME  non computer controlled With  elec chokes for trucks.

76 to 79 carbs are mostly hot air chokes and 80 plus could be either hot or electric choke. They are physically different looking at the front from the earlier 4MV carbs.
Hot air chokes are easily converted to electric but not so with the 4MV's

Commercially rebuilt carbs from autozone and such are generic butchered carbs. (Fits all) your better off with someone like SMI.
Summit sells a good carb  from a custom builder.

Most 80 plus quads are a diff design with single main air bleeds

Early 70's, late 70's  and 80 carbs have completely different jet rod combos.

If you have a carb that works then rebuild it or have it rebuilt by a reputable rebuilder. 

They are not all the same


Sent from my iPhone using Tapatalk

[LTZ C20]

Not only what blazer74 said but, if you can find a decent, used quadrajet, you could have it professionally rebuilt. Anybody who knows and understands Quadrajets will be able to build you a reliable, good working quadrajet. They are actually good carbs, just when downgraded and restricted for fuel milage and emissions it makes them not as good.

[st3vomettler]

Ok  thank you would the autolite carb for the 350 be to big for the 86 305

[LTZ C20]

I dought it. A quadrajet is about 800 cfm but restricted from the factory to flow much lower than that. You gotta be pushing out some pretty high horse power to need 800 cfm. The autolite should be fine as long as it's around 600 cfm.

[st3vomettler]

Idk how much cfm the autolite is the part number for it is c9394 but when I used to drive it to work and back it was 22 mile round trip and I calculated the gas mileage and it was less then 9 that is with a stock gear ratio and a th400 transmission with the 305

[LTZ C20]

Ouch. Man that's not good. I think you would probably have better luck with a properly adjusted q-jet or another good carb as blazer74 mentioned. I wouldn't trust an autolite carb.

[st3vomettler]

Yea I got a 1406 edelbrock carb that has to be rebuilt and I just put a camaro t5 transmission in it

[enaberif]

I dought it. A quadrajet is about 800 cfm but restricted from the factory to flow much lower than that. You gotta be pushing out some pretty high horse power to need 800 cfm. The autolite should be fine as long as it's around 600 cfm.

quads are either 750cfm or 800cfm. I have 3 800s but the 750s are more common as the 800s were found more in motorhomes or big blocks.