Quadrajet Question

[71 Blazer]

This is my first time messing with a Qjet, so bear with me if this is a not workable. I have 2 carbs one is off my 1988 emission heavy 454 and the other is of a 77 no emissions 350. The emissions have all been removed from the 454 and I want to put the carb off the 350 on the 454. If I change the jet size, metering rods, ect. This should work right? I am also going to be buying a book, anyone have an helpful hints on a good Qjet book or two?

 

[Hogback Fabrication]

The '77 carb (from the 350) will likely be a 750 CFM unit, the '88 carb will likely be 800 CFM (the extra 50 CFM is in the primaries to help part throttle on the bigger motors).

I would think the 750 would be fine on the 454.

The jets and metering rods will not interchange so you will have to tune the older carb (which isn't too hard).

The Q-jet book by Doug Roe is good.

 

[71 Blazer]

I forgot to mention that the 350 carb is only a few years old. I was bought brand new no more than 3 years ago, from some auto parts store.

 

[dyeager535]

I would think just rebuilding the 454 carb would be the ideal solution myself, presented with those two carbs. I believe the Roe book talks about APT and what not.

I've got the Roe book, I liked it, but there is one more book out there that I've heard people say is even better, just can't recall who it was.

 

[71 Blazer]

I had at one point tried to put the carb off the 350 onto the 454. It would idle fine, but when you hit the gas the 2ndaries on the carb would stick open and take me for a drive(ended up doing some rotor-tilling with duallies) not sure what would make them stick open, the butterflys work fine when it is off the engine.

The carb #'s for the one off the 350:
17058213
1428 BJB

The carb #'s off the 454:
17083204
2382 FRB

 

[Bent77]

Since the carb worked well off the engine, maybe you have some spring binding or other linkage disfunction. As was mentioned, the rods don't always interchange as they are different lengths.

I would try the '77s carb, get the linkage kosher before worrying if it needs re jetted. Might be good as is, but fix one thing at a time.

As for WOT w/ the engine running, turn the key off. Sometimes hard to do with white knuckles.

 

[Blue85]

What's wrong with the 454 carb? You will be tuning either way, so why not use the one that came with the engine? You haven't mentioned how the chokes or vacuum breaks are set up, but there could be big differences to account for when putting the older carb on a newer engine. A quick rebuild of the 454 carb with possible jet changes should be all that's required.

As for the throttles sticking open - could the carb have been over-tightened to the intake manifold?

 

[71 Blazer]

All the emmissions have been removed, including the wires that go to the carb. the truck ran fine it would just diesel some times when it was shut off. I am told these wires helped control idle. I thought it best to start with a new carb that was wireless than to keep screwing with one I didnt think would ever be right. Plus I already had this carb siting around.

 

[dyeager535]

OK, that makes more sense. If it's got wires going to it (other than choke) you may have problems making it run correctly. There are a few variations on the electrical stuff, from full computer control, to some stuff that is less critical for operation, but may still affect it.

 

[71 Blazer]

OK, I got the carb off the 350 to work right, I think it was torqued to tight to the manifold, because I just pulled it off and put it back on. I took it for a short spin, even spun the tires in some dirt, and everything seems to work great. My question is, isn't this carb running my truck lean? I know these carbs ain't like Holleys and are sensative to engine vacuume for fuel delivery. Will this carb work as is?