Rochester 4 Barrel M4ME Carb

Whats the best way to set these things for the proper cold settings for starting in the morning?? Some days she fires up, some days… geez like somebody sat there and pumped the throttle all night. Normally I depress the throttle once to the floor to set the choke…

QuadraJets usually start right up…UNLESS the welsh plugs in the bottom of the float bowl allow the contents of the bowl to leak into the engine…These plugs can be sealed with a special epoxy made for that purpose…

The leakage causes two problems. On hot starts, the engine can be flooded. On cold starts, the float chamber is dry and you must crank quite a bit to refill it before the engine will start…

You can check for leaking by turning off the engine, remove the air-cleaner and look down the carb bores with a flashlight, throttle held wide open…You should see no fuel dripping or a fog of fuel vapor. If you see either one, the carb is leaking internally…

Also, is there a choke pull off at the left front of the carburetor? As you face the engine from the front it would be at the 4:00 oclock position on the carburetor. Some Q-jets had it some didn’t. Without it, in some weather conditions, the engine starts and floods unless the throttle is aggressively pressed or it is left to idle until the choke heats and opens.

Yeah, this is on a 84 Chevy C-10 with a 350. Basically where all the cold idle linkage stuff is, on the passenger side… there is a lil vacuum pod at the rear of the carb, actually theres quite a few vacuum lines connecting up to the whole carburator itself… pretty insane, but it all works together somehow. I know theres an electric choke directly on the side of it… with the pod behind that, then towards the front of the carb, passenger side… theres a few adjustment screws… Im wondering if there’s a way to properly adjust these… once it warms up though… it runs like a champ…smooth idle and acceleration. Honestly, there’s quite a few adjustment screws all the way around the carb…dont wanna start just turning them all…

Believe me there are people who who rather work on that carbed mess than learn F.I. systems.

If you can find an OLD mechanic who knows carburetors you’d be way ahead. I will try to back track past repairs on those carburetors to see if I can find part numbers and installation specifications. There is a number, usually perpendicular, at the front of the carburetor and beginning with 17. Post that number please.

For your situation, I’d consider a good Holley carb, like the ‘Street Avenger’. There are plenty of models that are allowed under the California Air Resources Board, and can keep you compliant with emissions regs, if your area is regulated. These carbs are very tunable and much simpler. That carb your describing is a nightmare to work on, and you’ll have a hard time finding a decent mechanic that will want to mess with it.

All those vacuum lines, adjustments, and vacuum pods were attempts by the engineers to make these carbs a bit more efficient to meet emissions and fuel economy requirements of the mid 80’s. I refer to this period ('77-'88) as the ‘Dark Ages’ that followed the muscle car era. The '90s began the ‘Recovery’ period, where power, economy, and good emissions really began to return to balance.

Rod Knox,

I just looked up those carbs in a shop service manual I have for a long gone '78 GMC Jimmy I used to have. The manual covers from 1967 thru 1982. Maybe same carbs in '84?

One thing I’m wondering about is the Model number shown in the OPs post (M4ME).

My manual shows 2bbl and 4bbl Rochester carbs, but none with a ‘E’ on the end.

I do have a couple showing M4MCA and another with M4MC.

This pertains to rod adjustment.

On all carbs EXCEPT 17057586 and 17057588 place the pump rod in the inner hole.

Carbs WITH those numbers have the rod in the INNER hole. (FWIW)

Thanks for the advice… wish i could afford one of them new carbs… but hard times… luckily i have a new 350 block… but the carb is the second one after the original… im gonna have to make do, and adjust it to ear, and sound… i dont do bad… it runs real good at idle and when its warmed up… but the cold start… some days she’s good, and some days… wanna pull my hair out… thanks again for the info

Thanks again Knox

The Rochester E4ME(D) carburetors lists a “vacuum break” that is sometimes factory installed but not always. When installed and operating properly it pulls the choke open slightly, as soon as the engine starts. All the Q-jets seem to be drilled and tapped for the vacuum break and it is easily installed and adjusted. It has no interlocking linkage, it merely engages the tang on the choke and pulls it to the front when vacuum is applied.

Yeah, it has the “vacuum break” the lil pod with the oddly bent little rod to the choke. When i pull the air cleaner and have someone else start the truck… i see it suck back, and pull the choke… so apparently its working…dont think it holds it open slightly, actually it shuts all the way.

Did you get the I.D. # for my carb??.. Didn’t see the messages i left it on post on here… just curious… Thanks

The vacuum break with the odd shaped wire linkage is the rear choke pull-off. if you look at the front of the carburetor air horn (top piece) at the corner, facing toward the passenger side, there are two holes drilled and tapped. A front vacuum break (pull-off) will fit there and if your problem is overchoking on a cold start adding that part will correct the problem.