quadrajet

[kyle.rj133]

Im going to go get one from a salvage yard to get rebuilt. What years should I look for? is there a certain part/serial number to look for?

going in a 72 k5 with a very mild 350.

 

[76zimmer]

Kyler, I would check into an electric choke model for convenience...

here is a good starting point:

http://www.florida4x4.com/tech/quadrajet/500cid.com/Quad.htm

and the quadrajet modification book is a good one to read too:

 

[kyle.rj133]

I pulled this quadrajet carb off of a 1984 chevy van.

I was looking at pictures online and noticed the fitting in the red is missing. what is that fitting? the carb number is Rochester Quadrajet 17084226 0934 H0D

Is this something I should worry about? If you look in the hole you can see that it goes back in and up I think..

I also noticed this picture online that looks like its plugged. Could I just tap a hole and put a new inlet fitting or just plug it?

 

[76zimmer]

17084226 0934 H0D


170 Rochester div.
84 model year
2 Quadrajet Federal
2 Chevrolet
6 Auto trans

0934..production date...93rd day of year 84

81-86 Chevy GMC trucks.

That port may have been to an evap canister hose.???

 

[kyle.rj133]

17084226 0934 H0D


170 Rochester div.
84 model year
2 Quadrajet Federal
2 Chevrolet
6 Auto trans

0934..production date...93rd day of year 84

81-86 Chevy GMC trucks.

That port may have been to an evap canister hose.???

Thanks for breaking that down for me.. I ordered those 2 books you suggested.

I have no idea what that is for.. When I unhooked everything there was nothing in that spot Do you think I should look into getting a different carb?

Whats a good place to buy a rebuild kit from? I also found out that this carb is off a 305 non computer controlled. Will I need to change things like jets, rods, ect. to work for a 350?

 

[76zimmer]

I dont think you NEED to look for a different carb, but those books should explain what exactly that port is for...as I remember on my 85, it seemed like it was a well vent that went to the charcoal cannister for emissions purposes.
A Quad is a vaccum secondary type carb...meaning when enough airflow flows through the primaries, the venturi action creates the secondary air valve to open...now that can be controlled in about 111 different combinations....metering rods, hangers, springs, etc can all be changed to "tune" it to your combination...but I've ran a 305 quad on a 350 with Vortec heads, 460 lift cam, and .030 flat tops, and all I did was drill out the primary jets by two drill sizes...now these are very small drill bits and I don't remember what size they were, but that modification alone allowed it to idle really good on the 350. There may have been more performance available had I got into tuning the other items, but it ran pretty good, so rather than mess it up, I left it like that.
You can get a good rebuild kit from NAPA...a jiffy kit is a decent one and readily available. Be sure to check things like the choke pulloff, and set the angle of the choke plate etc...it will all be in the kit how to do that.

 

[kyle.rj133]

Besides a rebuild kit would you suggest getting anything else?

 

[79rustyk10]

I would have new throttle shaft bushings installed.

 

[wazzabie]

on the 78 4mc qjet that fitting went to the pcv valve. I suggest first getting a junker and tearing it apart. On my qjet I expoy the plug welds. Some say it is better to tap it but I also read by 78 it was not much of a problem as earlier ones. I went with a qjet the had a manual choke.

 

[kyle.rj133]

on the 78 4mc qjet that fitting went to the pcv valve. I suggest first getting a junker and tearing it apart. On my qjet I expoy the plug welds. Some say it is better to tap it but I also read by 78 it was not much of a problem as earlier ones. I went with a qjet the had a manual choke.

tap and plug it? or add a fitting and hook it up? why epoxy the plug welds? to prevent vacuum leaks?

 

[wazzabie]

tap and plug it? or add a fitting and hook it up? why epoxy the plug welds? to prevent vacuum leaks?

They well plugs are on the bottom. They can leak. When I rebuilt my carb I just used some jb welkd on them. The other option is to drill and tap in a plug which is a pernament solution but I felt could cause more damage if I were to drill to deep. The casting of these qjets seams to be rather fragile. They are not solid but porous.