'77 quadrajet or rebuild the old one???

[68gmsee]

Need to get some opinions...

I've got an older qjet carb (mechanical choke) on my 69 with 350 and it's needing some work. I have another nice one that came off a 1977 350 that's in good condition and has electric choke.

My question is if I use the 77 will there be any problems capping off the lines I don't need? And which one goes to the distributor?

pic of the 77 qjet...

[ChevLoRay]

If you know it's good and worth putting a kit in, go for it. I don't happen to like any of the early emissions carbs. So, I bought a new Q-Jet from Edelbrock. Never happier with a Q-Jet, than I am with this one.

[68gmsee]

Chevloray, the 1977 qjet seems to be in real good shape and probably doesn't need any work done to it for now. At least, I hope...

I intend to eventually go back to the original configuration, but for now I just needed to know if there would be any problems with blocking off all of those extra openings for the emissions crap on the 77's.

[neonlarry]

Blocking off unused ports will not affect the performance of the carb. As to which port to use for vacuum advance it depends on if you want to use ported or nonported vacuum.

[68gmsee]

Originally Posted by neonlarry

Blocking off unused ports will not affect the performance of the carb. As to which port to use for vacuum advance it depends on if you want to use ported or nonported vacuum.

Thanks for the info, larry, but when it comes to the later quadrajets I'm a total moron. Not sure what you mean by "ported or non ported vacuum" and how will it affect the performance. This is basically a work truck used for hauling and pulling.

[68gmsee]

Okay, I did a search on ported vs non ported and found out what I was needing.

The port above the butterfly is the ported vacuum and the ones at the base are the manifold vacuum. I will check them with my vacuum guage. From what I read it doesn't matter which one I use. I just have to determine which one my engine likes better.

I need 2 ports for my 350. The pcv one in front and another for the vacuum advance. I'll cap off the rest off...

[ChevLoRay]

How long has this '77 carb been sitting around? Was is rebuilt and then set up, or pulled from a running vehicle and stored? I would replace the accelerator pump (dried out) and pull the throttle plate from the carb and be sure the plugs in the base of the bowls are not leaking. This is the source of most of the ills that Q-Jet's are notorious for having. You can buy the plugs from NAPA and the foam pieces that fit into the base plate to help hold the plugs in tightly.

[68gmsee]

ChevLoRay, not sure on how long it's been sitting. I am sending the older one out to have it cleaned and redone so I'm just going to install the 1977 one to see if it works until I get the other one back.

If it doesn't work good, then I'll just park the truck until I get my other one back.

Thanks for the help..

[neonlarry]

The later Qjets usually don't have a problem with leaky well plugs, they changed the plugs to solid ones instead of stamped ones.

[DieselEater]

Buy Cliff Ruggles book on Q-Jets!!!!!!!!