Does anybody know where I can find the specs; jet sizes, metering rod sizes etc. for a Qjet on a '68 400 auto??

Thanks, Mike

if you are patient and good at crossreferencing, you can find all the original specs on http://www.1968firebird.org/index.html

you might get 2 or 3 options.
the original parts will only be a rough guide anyway, for optimum tuning of your specific engine and climate. I dont know if the difference in fuel from then and now make a difference in tuning, but I bet it does.

I found the original specs, and this article:
http://mywebpages.comcast.net/gtopercy/Pictures/QuadrajetTech.html
very helpful in getting mine close.

edit: 1968firebird.org seems to be down. hopefully it will come back up. there are a couple mirrors of it in different places...
here's one: http://209.237.45.104/index.html

original carb should be 7028264.

a couple other sites which came in handy for me:
http://www.hioutput.com/tech/qjetrod.html
http://www.edelbrock.com/automotive/carb_qjet_access.html

Or this one:
Q-Jet Tech Notes

The problem with "specks" is that today's gas, and the gas of yesteryear's specks the different puppies.

Headers alter flow. Unlike factory "duals" dual exaust of various sizes also alter flow. Cam, spark advance, stall converters, rear axle, and all kinds of varibles--such as the aforementioned altidude/climate--make it impossible to have given specks.

I have #71 primary jets in my carb, and the car can eat all the food distributed the primary circut. It had smaller jets--I think about #67 or so. Smaller jets have proven to decrease performance, but it's anyone's guess whether or not larger jets would make the car run better #71's are the largest ones that I could find.

If I can remember, I'll take a look and see what metering rods and hanger I have.

My question is where the heck do you intend to get the jets, rods, and hanger? If you know where these parts are sold, please let the board know because there are lots of people who would be interested in knowing of a source.

Edelbrock Jets fit Q-Jet carbs, as do the rods. I don't think they sell the secondary hangers.

They have a choice of 5 hangers. They are listed on the link i provided for edelbrock.com. Partsamerica can get some of those edelbrock parts too, but not all. I got the powerpiston spring kit (#1994) thru them.

Edelbrock has jets from .068 to .077, in case you're interested Amervo.

All, thanks for the response's . P.M.I. USA, thanks for the awesome Qjet tech document!.
My car is numbers matching EXCEPT for the carb, it's a '75 vintage Pontiac. I'm either going to find the correct carb, or restore this one.

I'm not sure that when the carb was swapped, that the original internals from the '68 were re-used (jets, Mrods)...knowing what is supposed to be there helps

FWIW, the car runs perfect...so I'm hesitant to change anything...

Thanks again for the responses!
Mike

Chances are they just swapped the '75 carb on your engine. What is its number?

The Carb # is: 17054905. could this be a service replacement for the original? I know the SD455 service replacement is: 17054910...I can't find any application for my carb and the numbers don't decode right.
Anybody have any info on this carb??

Thanks again, Mike

1968-1969 350, 400, 428 Pontiac service replacement carb, according to http://www.thepontiactransampage.com/carb4.html and http://thepontiactransampage.com/carb5.html and http://www.classicalpontiac.com/qa7/display.cgi?directory=topics&number=58771&title=Carb.+

****! I forgot to take a look at the rods. Sorry. You know, there is a rule that lots follow that claims that if it runs fine, don't dink with it.

Thanks for the info folks. I think that I have the secondaries maxed out, never could find any rods/hangers. But I would like to try a size or two larger jets because the engine seems more than able to gobble up whatever the primaires deliver. A while ago, I beat the search engine trying to find jets, rods, and hangers with no luck. I also saw an assortment lot of rods for sale on eBay. The seller claimed them to be hypo. However, the problem was that the pictures of the rods clearly showed rods with almost zero taper.

If I remember to pull the rods, I'll also take a picture of them so that people who aren't fimiliar with identifying gas guzzeling rods know that they look like. From what I've seen in rods, I think mine are fairly high on the agressive side. As with the hangers, I cannot remember how many, but I think that 5 sizes are about all that were ever made.