First quadrajet rebuild

[chevyguybc]

Hey guys, im only 20 but have owned around 30 cars/trucks,

most GM cause im a gm dude, anyways, im going to be rebuilding the carb that came on my dads 78 pontiac catalina he just picked up for cheap, its a pontiac made in canada so its got a chev 350 in it.

anyways its got all the emssion crap and its got the manifold vacume idle, not the electric

any links to good sites out there with info, or tips from you gurus? thanks for the help

btw, gunna be a member as soon as possible

 

[chevyguybc]

no one got any tips or suggestions, im not a noob at all, but never attempted a REBUILD on a quadrabog

 

[1-ton]

Some things to look for are worn throttle shaft, leaking well plugs, and bad float. If the throttle shaft is worn out (and it probably is with a 1978 Q-jet), then the shaft will need to be rebushed. This takes some know-how to acomplish. The well plugs on the under side of the throttle plate are probably leaking as well. You will need to apply some epoxy or ceramic sealer on these, and go ahead and replace the float while you are at it.

I personaly do not like rebuilt Q-jets. There are some real pro's out there who can do an excellent job rebuilding Q-jets (they will charge as much as a new carburetor costs), but the majority of carburetor rebuilders out there are hacks, who employ minimum wage immigrants, to crank them out in large volumes. I say your best bet is to buy new, if you want to make damn sure you are getting a carburetor that performs as efficiently as possible.

 

[hack500]

pick up doug roe's book on quadrajets

 

[77crewcab]

Take your time and keep everything neat and clean as you lay out all the parts. The actual disassembly and reasembly isn't that hard. Deffinately get the Doug Roe book to know which small details to look for. There are a lot of tunning tricks that can be done to make it run better than stock but for the first time rebuild I would stay away from them. Just do a basic rebuild and put it on and tune it. Once you are able to do that then maybe look at some of the finer point of tunning.

 

[89GMCSuburban]

As said, rebuilding is cake. Tuning is a nightmare, and pretty much I hear it's is VERY hard to get it back to normal. Very few people out there left that can actually tune them well.

 

[dyeager535]

pretty much I hear it's is VERY hard to get it back to normal.

This is why if the choke works ok, I recommend that you leave it the hell alone when rebuilding, as it's one of the hardest things to get back to working right. Don't even touch it. Undo the linkage from the choke plate, and leave the choke linkage be.

APT is another thing you don't touch unless you plan on playing around with it a bunch to get it back to correct.

Everything else in a rebuild (IMO) is pretty much unbolt, clean, and reinstall. Float setting is a bit particular, but that's a given on any rebuild.

 

[Trigger Creep]

I've rebuilt many over the years. For dependability and response, you can't beat a new one. There are companies that sell new Q-jets, direct replacements for the original.

The one thing I can add is look at the Edelbrock Q-jet replacements. They're a lot more dependable than a re-build.

 

[chevyguybc]

cheers guys, great responses...

i got the electric choke working good for the catalina, it rusn great.. i think we may take it to a shop to tune pro