Quadrajet upgrade

[Vintage Windmills]

Looking to get my original carb for my K20 rebuilt by SMI or purchase one of thiers. They said theirs have a booster design for better mpg? Anyone experience this and know how much more efficient these (newer i assume) carbs are? Would like to keep my truck more original since its numbers matching but if I would pickup 1-2 mpg I would store my original carb and run a different Q jet. Difference in price is about 125 cheaper to rebuild my original carb. Also, will the newer one use the same linkage and choke control including the little thermal coil on top of the manifold?

[stope4]

Ask them about the linkage. It should be the same. Doubt if their booster or whatever is going to do anything. I'd get the original rebuilt. The old quadrajet wasn't a bad carb. If you don't drive vehicle that much, just use some type fuel stabilizer in gas while vehicle is sitting. That will keep the carb from gumming up.

[Sport/Truck]

I'm running an SMI and really like it. I'm curious what Sean is talking about. I ordered it a few years ago and its stage II IIRC.
It was totally plug n play.
s/t

[70cst]

Originally Posted by stope4

Ask them about the linkage. It should be the same. Doubt if their booster or whatever is going to do anything. I'd get the original rebuilt. The old quadrajet wasn't a bad carb. If you don't drive vehicle that much, just use some type fuel stabilizer in gas while vehicle is sitting. That will keep the carb from gumming up.

[davepl]

I just had my numbers-matching Q-Jet rebuilt at Carb Connection in Kirkland, WA, who is apparently well-known in the Q-Jet world. It cost $350 but that was more than just a rebuild, it included replating the body and the whole deal, so it looks like new.

Honestly I'd stick with the factory carb. Those engineers went to good schools, and while their work can certainly be improved upon, I'm leery of any "super carbs" that offer increased mileage and so on.

A good clean and properly adjusted carb makes all the difference. If you have all the driveability stuff the factory did (heat risers, crossover, air stove, original cam etc) when properly set up they run as well as modern fuel injection. It's only after we monkey with them "improving" things (or a lot of wear and age) that they get hard to live with!

[69sixpackbee]

I too am running an SMI stage II.
Glad i did.
Took off that stoopid EZ-EFI and went back to simplicity. Not only does it run better it gets better mileage too! And it has a choke that works unlike a stoopid fuel decay program with an IAC that never worked as it should and,...the list goes on.
SMI carb all the way!

[davepl]

Well, a properly tuned EFI will beat a carb every time, but the factory spends something like a hundred thousand hours doing the base config for a modern car. No experience with EZ-EFI, but my BS3 Camaro 502 fires cold and runs properly... but it took time to get it there.

It probably comes down to the fact that whether its a carb or EFI, either one needs to be done right. And carbs can be just as spooky to some as EFI is to others, so its wherever your comfort zone is I guess.

[Vintage Windmills]

So I asked Sean for a little more info and here is what he said.

"Est. at least 1 MPG. It was the design they used in all ¾ and 1 ton trucks after 1979. It was used exclusively in trucks. Linkage would bolt right up"

I did a little math and the extra cost would be recovered after 5000miles so I'm a little on the fence still, what would you guys do given this info? It may take me 2 years to put that many miles on.

[capev86]

the Q-jet is a great carb (my choice over a holey or an edelbroke), but the later models (1977+?) have some revisions that make them even better. the few (and proud) shops that beef up the q-jet are making use of modern tech and fixing the minor flaws in the design to make it bulletproof (brass bushings on the shafts, permanently fixing potential leaks, etc). you could always run the tuned carb and keep the matching numbers original for a rainy day (or be able to drive your truck while you are having it redone as well).

[duallyjams]

JMO but your carb rebuilt and tune correctly will get you 1mpg or more.

[capev86]

there are a couple write ups on how to do an ultimate rebuild on a Q-jet. there was also a segment on Musclecar (PowerblockTV) couple years ago and they covered it all including the fixes that should be done at as part of the rebuild. also check these out:

http://www.recarbco.com/technical/rochester/qjet.html
http://www.carbkitsource.com/carbs/t...jet-index.html
http://www.quadrajetcarburetors.com/...tructions.html
http://www.cliffshighperformance.com/parts.html