jet-tech

I have a Rochester Q-jet on my 1966 327, A.I.R. Powerglide Vette. The carb p/n is 17054929 and date code 2781. From my recon it's manufactured between 1974 and 77. I not sure what the CFM is, maybe 750. It smells like fuel after shutdown and sometimes hard to restart after engine is warmed up. Is this Carb worth rebuilding or should it be replaced with eddy 600 CFM carb or other aftermarket carb? Any info on this Q-jet would be appreciated.

Stan's Customs

Call SMI and speak with Sean...he's a legendary carb man from all kinds of Hot Rod and other magazine articles that knows these carbs as well or better than anyone in the country....and is reasonable.

http://www.smicarburetor.com/

Stan...

Plasticman

Just about all carbs smell like fuel after shutdown due to the "gasoline" we have today (far cry from the gas we had back when carbs were in vogue).

Note that a Q-jet uses a spread bore bore pattern, so unless you are wanting to change over to a square bore pattern intake manifold, your choices are limited. Don't even think of using an adapter.

If your carb is from the mid 70's (and it most likely is, since I have a slew of Q-jet numbers, and that # is later than my 60-70's list), it is not optimum either. Not the worst, but could be better.

Plasticman

jet-tech

I just did a members check on my intake manifold and heads. Manifold is not original #3927184 from 1969 300-350 HP. Heads mercilessly are original. Any info of the performance on this manifold vs a new Edlebrock performer?

One note, the A.I.R. system had been removed before I bought the car. And the PG is next to go.

Stan's Customs

The manifold change by itself is not enough to matter for daily driving. Just have SMI build your carb and enjoy the car. CALL Sean..he'll tell you what you need to know..and he builds them all...Holleys , Q-Jets ..you name it!

There's no good stopping place when you start upgrading....heads, intake, cam, gears, headers ...and while your at it might as well etc. etc....

If you plan on doing more.. better plan it all from the start ...so you won't have to do some things twice.

FYI..I have a Q-jet from SMI for my '61 restomod...I considered everything, F.I. systems, single carbs, two fours, everything...

...but I was in the garage business many years and the Q-jet has always been my carburetor of choice over all others. They are great for for driveability...reasonable gas mileage ....and I love the way they sound from a tromp...and I've built hundreds of them. It would have been foolish for me to do anything else...

There are many good choices...but a Q-jet will perform very well ...when properly done.

Good luck...Stan

landshark 454

If the car runs well other than the smell and the hot start issue, there is probably nothing wrong with the carburetor. As mentioned already, the problem is today's fuel. It is made to be used in a sealed system, with the fuel under pressure at the injectors. They have added things to work under these conditions, but it causes the fuel to vapor off at lower temperatures, which causes flooding and vapor lock after a hot soak. Besides installing a thermal insulating spacer or plate under the carb, there is little you can do about it, other than running racing or aviation fuel, which, because they may contain lead, and have not been taxed for road use, are illegal to run on the street. Or you can install an electronic injection unit. ( The factory mechanical injection has even more problems with this fuel than the carb cars.)

So it boils down to; live with it, or get a newer car.

Stan's Customs

Sorry Shark...but it really could just be the carb too...

Quadrajets are bad about leaking down via a plug in the base of the carburetor. Which causes causes the smell and hard starting after it leaks down...

It's an easy fix...

If you want to be sure before you spend any $$...talk to SMI as mentioned.

Happy trails...Stan

Frankie the Fink

I ran a Rochester Q-jet on my 350ci Pontiac for decades in the 70s - prob same era carb as you have. The pre-emission versions are nice carbs and worth rebuilding and I'd take one all day long over an Edelbrock. Note Plasticman's comments about the spread bore though if you're considering a swap anyway.

Stan's Customs

Frank and Plasticman are right...and why I mentioned having a plan before you do anything.

If you plan on a Holley and a square bore later...better get a square bore intake and carb now.

MikeM

Quadra-Jets have always been bad about the floats absorbing gas and getting heavy. That can stop the float from shutting off completely and cause the gas smell and hot restart problems.

From memory (which seems to fail too often) any Quadra-Jet that has the part number starting with a "1", or 8 digit part number is a later, smog era carb and not the best choice to use.

jet-tech

Thanks for all the advice. leaning towards replacing the intake manifold and carb with Edelbrock performer combo. I know fitment with stock looking air cleaner is going to be a challenge.

Stan's Customs

Ahh well, go figure.....the Edlebrock fit all package doesn't touch a carburetor from SMI of any kind. Just like there is a difference between silk and burlap....lol.

If you want some "real" information once again talk to Sean...save your self some misinformation headaches...and $$$...

His stuff will be jetted for your application.

Just sayin'...Stan

jet-tech

Thanks Stan, I will call Sean before before I make up my mind.

Stan's Customs

Frankie the Fink

Just don't ever install the Q-jet "hot idle compensator" in backwards. I did it once and the car shut off once it warmed up. Duh !

jet-tech

Does anyone know the CFM of Q-jet p/n 17054929? Built in mid 1970's

Vetterodder

According to what I found on Google, it's from a `74 pickup. Most likely 750 cfm rated. Keep in mind that it's unlikely to achieve full airflow (750) until about 9k rpm on a 327. Even though the secondaries never fully open in real life (on a 327), they are still good carbs. IMO, better than an Edelbrock.

Stan's Customs

CFM is not as much a factor on QJ's as other carbs. It is what it needs to be, because of the vacuum secondaries, small front venturis and metering system. They come stock from the factory on 305's to 454's .

Whatever they came on they are all pretty close in cfm. (750/800) .

PAmotorman

17054929 1974 350/400 truck service replacement carb 750 CFM

PAmotorman

between 750 and 800 CFM Q jet carbs. 750 on the left 800 on the right. the difference is only in the primary side