The Stovebolt Site Forums The Parking Lot Big Bolts 503 engine huge Holley 2 bbl carburetor

I'm getting ready to remove and rebuild a Holley Model 885jjg carb, list # 1062 from a 56 GMC 630. It has sat for decades. I would prefer to eliminate the governor, but my brief research shows that the gov is an integral part of the operation - that in fact it holds the butterfly open at rest; and when the engine is started the governing function brings it shut. I'd like to keep this carb, but not sure what I will think after taking it apart and trying to find parts for it - especially parts to repair the governor. Do any of you have experience with this particular carb? It apparently was used on 55-58 503's.

Hi jaycoop. I have a little experience with the centrifugal/vacuum governors. My '57 2 ton has the 283 V8 with the stock Rochester 2G 2 bbl., it is built specifically for the vacuum governor application. You are correct with the operation of the throttle, the throttle shaft is not directly connected to the peddle linkage, the governor spring opens the throttle butterflies as the peddle is depressed, if there is a high vacuum it will allow full throttle, if the vacuum is low it will only allow the spring to pull the butterflies open part throttle due to the governor diaphragm opposing it. GM used 4 bbl. Holleys with that same style governor on the 366/427 truck engines into the early 1980's. If you find that your carburetor is beyond repair, you may be able to find one in a junk yard with medium duty trucks. If you want to delete the governor, I would think a normal Holley would bolt right up. The shop manual for my truck spec's the governed RPM at 4000, I don't know about the big GMC engine but I would think it to be close to that. I have a Holley 2300 2 bbl. 500 CFM in the barn, I can measure the bolt pattern for you.

Thanks buckshot! I pulled the carb today and will see what I can do with it before deciding anything. I do see where a couple of carb shops online have some parts for these, but I'll open it up first to see how salvageable it is. I will try to attach a picture of it. It's a big beast of a thing with a large float bowl on the top.

Whew! not what I had pictured. The bolt pattern does not look like any modern Holley. Reminds me of a float and bucket trap for 2 pipe steam heat.

Contact Jon at his website, "The Carburetor Shop"- - - -he posts on this forum as "carb king". If Jon doesn't have a kit on hand for that carburetor he can make one, and it will fit right and work right the first time around. Jon has a massive stock of oddball carburetors, and parts to repair them, plus the knowledge to guide you through a rebuild.
Jerry

Jerry, Thanks for the lead! Parts and help will be needed.

HERE IS the website for The Carburetor Shop. HERE IS carbking's profile. His email address is there and you can always PM him.

Thanks Peggy for the added info! I like to wrap things up on the forum, so I'll let everyone know what happened. I opened up the carb to find it amazingly clean. Hard to believe. Looked like someone had rebuilt it not long before it was parked circa 1990s. The only part I was worried about was the pump plunger, but after soaking it in gas, it functioned well. I tested the governor function and it was good; the gaskets were reusable (I did resurface the carb cover to get a flatter surface). This carb is a unique design, a concentric setup, like a carb inside a carb. I have the original repair manual, which is amazingly well written and illustrated, making work on this carb easy. I just installed it yesterday. I also pulled the fuel pump which tested good and am now cleaning out the gas tank. Then it will be on to electrical. I also had been soaking the upper engine with an acetone/ATF mix, and have turned it several revolutions at the crankshaft pulley, so it is free!

Jay, thanks for the feedback on the carb. Looks like you are onto the next few things now. Hope you'll see you in our Virtual Garage again. We're here if you need us, or just to report back on how things are going in general.

Big carburetors are fun to work with. Some of the ones that were used on radial aircraft engines in the 1940s were massive things, designed to support engines displacing a thousand cubic inches or more. When my father's competitors on the Tennessee and Kenticky dirt tracks in the early 1950s were running three Stromberg 97s, his car ran a single BIG Zenith 2 barrel for an Interrnational truck inline six engine- - - - -and outran them routinely.