My '68 327/350 engine has a carb with the following ID No: 7029200 EE 1941. My research shows this to be off a '69 396 motor. The engine was rebuilt and has sat for some time prior to me purchasing it - runs, but very rich.
Any ideas on whether or not this carb is compatible with my engine? I'm a novice with these carbs (and early c3's as well), so any advice is appreciated. Scott

 

Ack!! Just realized you said it had sat for a while... the carb may need a good rebuild with fresh components. When my carb was rebuilt by Lars, it needed a new accelerator pump due to damage from the reformulated fuels (I think it got stuck or rotted by the new fuels). Anyway, if it has sat, a carb rebuild may be in order. Along with correct metering rods/jetting and fuel enrichment settings that are normally part of a carb rebuild.

Lars usually does the following verification activity with his rebuilds (he did for mine). If you engage him for the work (if he is still doing it), he will need to know all of the particulars of your power combo...
My first suggestion would be to check the sizes of the main and secondary metering rods. There is a wealth of information regarding the proper metering rod sizing. Sounds as if your metering rod (diameters) are too small, resulting in too much fuel getting to the engine. If they have the metering rods for a healthy 396, I'd definitely suspect the metering rods. However, if you step up the metering rod sizes, you may also have to get larger jets.

If Lars still rebuilds them, he would be a great source to help you dial that q-jet in for optimum performance on that 327/350hp engine.

I remember when Lars rebuild my q-jet on my '80 L48. I had just had a tuner work on the carb and distro and the tuner destroyed my metering rods with a grinder; all of the performance improvement was from a good recurve. Lars set the carb up for my parts combo and, save for a secondary metering rod replacement via the mail, the carb was setup perfectly.

Best of luck and send updates!

 

I agree. Lars is the man.

 

The carb will work for you if it is rebuilt using the correct jets and rods for your engine. Since the Q-jet is a "demand" type of carb, all of them are very much the same except for jets/rods and minor feature differences. Do a "SEARCH" of the Forum archives for a paper by Lars Grimsrud on proper jets/rods for your engine. Do the rebuild yourself using another Lars G. paper or send to him for a perfect rebuild (V8fastcars@msn.com).

 

Thanks guys for the replies. It's good to know this carb has potential. Lars emailed me back and verified this as well. It's time to start getting educated on archived material. I'll be adding some photos tomorrow -- I'll have a few more questions. (probably for the next five years!)
Also installing an HEI distributor w/mech tach drive and vacuum advance. Scott

 

I would like to read Lars' paper on the proper jets and rods for a Q-jet also but I'm not having any luck and need a lesson on how to "SEARCH" to find it.

 

Eng40,
Try BarryK's 'info on timing' at the top of the tech section. There is a link to Barry's website with various articles/ tech papers. I'm sure there are many other sources, but these will keep me busy for a long time.

 

For the latest listing of all available tech papers, and to obtain the latest version of those papers, you have to e-mail me directly. There are no web sites that keep the latest versions of the papers.
Lars
V8FastCars@msn.com

 

Thanks for the reply Lars, I'm reading your "How to tune a Q-jet" now and I don't want to hijack this thread but I'm trying to find out if my non original 7037213 AIR only carb, which is on the engine, is jetted the same as the original non-Air carb which I no longer have.

 

You can't compare one carb's jetting to another - it's meaningless. It's like comparing the jetting in a '49 Cadillac Stromberg carb to the jetting in a '64 Impala 4-Jet - there is no relevant correlation. The variables between one carb number to another, even though they're all Q-Jets, are so significant that the comparison of one Q-Jet's jetting to another is meaningless. You have to jet each carb to its carb number baseline and tune from there based on the requirements of the engine. You cannot "make" a Vette carb from a Truck carb by installing the Vette jet size.

In answer to your question, the '67 carb you have will not be jetted the same as a correct carb for your Vette.

 

Believe me, Q-jets tuning is a sience! But the fever comes when the final carb is fitted and tested in practice.
After I studied Lars' 27 pages thoroughly and thought I got crazy I read over and over again Cliff Ruggles' book with 130 pages and after weeks I felt I had enough insight to start a Q-jet rebuild and modification to fit on top of my 1979 L82. During the 4th time I read Cliff's book I made 30 notes!!! and added some valuable tips from Lars, all of interest for mod. and tuning. I listed them in an excel file column and added several other columns with all kinds of parameters or remarks. For those who are interested I send it on request as it might work as a starting basis. From yunk yards in the Netherlands I bought 4 Q-jets to canibalize and got started. Since it was the first time I did a Q-jet rebuild it took a lot of time (which I do have in early pension).
My advice: Don't do it yourself unless your are convinced you can do such a precise specialists job and will take the time it needs. On the other hand it grants a great satisfaction when the beast comes loose and so it did (with thanks to Cliff and Lars).

 

Maybe this fall I'll get in touch with you to do a little super tuning on the carb. I'd like to get it matched up to the mods that have been done to the engine.
Thanks for the information in the Q-jet paper, it's very well written and easy to understand!

 

Packed up the Q-jet and sent it off to Lars today. Progress has been slow - not much in the budget until I sell the '82, but I hope to have it running in a few more weeks. Anyone know of a good tuner in the atlanta area? Thanks again for the info. Scott

 

I just installed a new distributor with vacuum advance. Can I tap into the manifold vacuum source at the hose just in front of the coil or does it need to be a stand alone source? (above photo )

 

Did the carb in question have a vacuum port in front for running a distributor? it has to be the right amount of vacuum..

 

The carb does have vacuum ports that are capped off. The tech papers I've read mention setting the vacuum advance off of manifold vacuum. I assume that means directly out of the manifold versus a port on the carb.

 

the big port at the front or the back of a Q-jet is manifold vacuume.

 

A couple of notes:

First, you are running a 1969 "Hot Slot" heat shield on your manifold - that's not needed nor doing anything for you on the aftermarket manifold you have. Remove it and just use the base gasket I will provide you with the carb.

The carb has several ports for manifold vacuum that you can use for the distributor. The best one is a long tube that sticks out on the passenger side - that tube is manifold vacuum. In fact, all ports on your carb are manifold vacuum except the forward driver's side port which is ported vacuum.

Lars

 

Thanks for the info Lars. I'll remove the heat shield.

Anyone have a photo of a '68 327 with the correct fuel lines from the fuel pump to the carb? Rubber versus steel lines, which is the way to go?

 

Never use a rubber fuel hose after the pump. If the hose goes bad, you don't want pressurized fuel spraying all over the headers, etc... Either buy a ready-made set or make your own with pipe cutter, small tube bender and a flare tool.