60 (62) Corv Carb

[Terry K.]

[John H.]

Re: 60 (62) Corv Carb

Terry -

The only carb that manifold was made to work with was the WCFB; I doubt if any Edelbrock replacement (which are AFB's) will come anywhere near fitting it. A later '62-'65 intake that was designed for an AFB would probably accept an Edelbrock replacement carb.

[Terry K.]

Re: 60 (62) Corv Carb

John:
Thanks - would a later intake - like 14057053 work?

[John H.]

Re: 60 (62) Corv Carb

That's an aluminum Q-Jet manifold with no oil fill tube hole and an EGR hole; not a good candidate. Better choice would be casting #3799349 or #3844459 - they were used with AFB's on 300hp engines from '62-'65.

[Terry K.]

Re: 60 (62) Corv Carb

John:
Your data sources are AWESOME!!!! I don't think I could ever come up with that information and you do it 10 minutes! Thanks!

[Joe L.]

Re: 60 (62) Corv Carb

Terry-----

Unless originality is a concern here, I'd think twice before replacing the Q-Jet. In my opinion, anyway, the Q-Jet is the best street 4 barrel carb ever made. Period. Hands down. GM invested MILLIONS in the development of this carburetor and they could afford that investment since this carburetor was used in so many applications once-upon-a-time that it's development cost could be amortized. You'll NEVER see that sort of thing happen again with a carburetor.

Q-Jets do have a few weak points but, overall, they can't be beat. How does one deal with the weak points?

1) seal up the soft plugs in the bottom of the fuel bowl assembly with epoxy;

2) replace the float EVERY time the carb is rebuilt.

That's all there is to it.

[Dennis C.]

Joe... Was the Q-Jet manufactured...

...in a variety of CFM models, or are they all quite the same. Please enlighten me, if you would. DC

[Joseph T.]

Re: WCFB's

Joe..any issues with using the WCFB's from Chrysler's on GM intakes..other than linkage issues?

Joe T

[William C.]

Re: Joe... Was the Q-Jet manufactured...

Airflow wise I beleive only one or two versions, but they are very "tunable" and GM spent a significant amount of effort to tune the carbs (by part number) for each specific application. I ran a Q-jet on our '67 Chevelle SS car back in the NHRA days (early 70's) and I also raced the exact same car and engine with an 800 holley in AHRA. Difference was about a tenth in the 1/4 mile, but for street use, the Q-jet will give better drivability and fuel economy than a similar Holley.

[Clem Z.]

there are only 2 CFM ratings for Q jets

750 and 800 with the 800 having a slightly larger pri throttle bore. GM limited the air flow on some by only allowing the seconary air valve to open a certain amount. this could be changed by modifing the air valve stop

[Joe L.]

Re: WCFB's

Joe-----

No mounting problems that I know of. That doesn't mean, for sure, that there aren't any problems, though.

[Joe L.]

Re: Joe... Was the Q-Jet manufactured...

Dennis-----

I don't think that GM ever actually published CFM ratings for these carbs, but the otherwise measured/accepted values are the 750 and 800 CFM that clem mentioned. So, unknown to a lot of folks, the Q-Jet has a CFM rating comparable to the largest Holley carbs of the day (of course, not as large as the "monster" carbs developed by Holley and others since then but generally unsuitable for any street operation). The beauty of the Q-Jet is the small primary/large secondary configuration. This means that a carb with the 750-800 CFM rating, with just jetting/metering rod changes can be used for virtually any displacement engine application.

The small primary/large secondary provides for gret fuel economy under normal cruise conditions. Plus, the air valve secondary makes for very smooth and pretty much "bogless" secondary cut-in.

The biggest quandry I faced in selecting the component configuration for my "ZL-1" was whether to use a Holley carb or a Q-Jet. My brain said to use the Q-Jet; my heart said to use the Holley. I went with my heart. I hope I don't regret it, but I have a feeling I will. I may just decide to change it at some point. The problem is to change it, I have to change intake manifold and cylinder heads. That's why it was such a quandry when I selected the components. Why does one have to change intake manifold AND cylinder heads to switch from Holley to Q-Jet? Well, obviously, the Q-Jet requires a different intake than the Holley. However, the ONLY aluminum big block Q-Jet manifolds that will fit under a stock 68-72 big block hood are the 68-69 Corvette L-36 manifolds and the Edelbrock Torker II. I wouldn't use the Torker II, anyway, since it's a single plane manifold but all of these manifolds are oval port. So, that means that one also has to change the heads to match the manifold. That's why it's a MAJOR proposition to change carbs.

As I previously mentioned, the Q-Jet is an absolutely wonderful street carburetor. Perhaps not the best carb for all out racing, but the best for the street (which is primarily where most of us use our cars). Q-Jets get maligned a lot. Mostly, by folks that don't know a lot about the virtues of a good street carburetor and are stuck on the cache of "Holley".

It's a complete shame that the Q-Jet is now completely out of production. GM ceased manufacturing most of them quite some time ago. Edelbrock contracted with some carburetor manufacturer (Weber, I think) to make them under Edelbrock's brand for several years, but that's also been discontinued. No problem for me---I've got four NOS Q-Jets + several perfect cores (owned, used and previously rebuilt ONLY by me) just waiting for the day I ever need them [absolutely NONE for sale]. So, "I'm covered" for the duration.

Used and rebuilt Q-Jet carbs are quite plentiful, so they'll be a good supply of them out there for a long while. The problem is that a lot of the cores have been damaged by the leaded gasoline which was ubiquitous in the hey-day of these carbs. They've also been damaged by "klutz" mechanics doing things like "hogging down" the idle mixture screws and other "dumb" things.

[Terry K.]

[John H.]

Re: 60 (62) Corv Carb

Terry -

That intake is #3905393, cast iron Q-Jet, used on '66-'68 Passenger, Chevelle, Camaro and Nova (never on a Corvette); yours was cast on November 10, 1968, so it's most likely a service replacement.

[Terry K.]