Trying to restore my 1969 427 intake and carb set up back to original and finding conflicting information on the carb. I know the carb is suppose to be a 7029204 but some of these have a flat top side throttle lever and some are rounded even though they both have the same stamping number.. Can someone tell me which one is correct. Thanks in advance.

 

Send an email to Lars Grimsrud at v8fastcars@msn.com, unless he answers directly. He is the resident guru on the Quadrajet amoung other things.

 

Yep, Lars is great to work with and can help with your questions.

 

Ok Maybe I'll try that Thanks

 

The '69 throttle levers have the rounded tops, both small blocks and big blocks, except the '69 "SR" carbs produced after 1969. The big block carbs had the bottom part of the lever chopped off by the factory to clear the intake manifold. This is a correct 7029204 carb & lever:
















This is a '69 small block throttle lever. The small block carbs had provision on the lower throttle lever for attachment of the TH350 kickdown cable. The TH350 was never used on the big block applications, so the big block carbs had no provision for the cable attach:


1969 small block "SR" carb with the squared-off lever:




Lars

 

Wow Thank you so much for the reply and the pictures. They where right ..... you are the "go to guy " for carbs

 

Is that long vacuum port sticking out by the choke pull off for the transmission modulator valve?

 

That is a manifold vacuum port. Refer to the AIM for you car to see how it was used from factory. Most folks use it to feed vacuum to the advance can on the distributor...rather than from EPA required "timed/ported" vacuum fitting.

 

look at the diagram in the link below. Appears to go to air pump.

https://www.corvetteforum.com/forums/c3-general/4036378-68-327-350-quadrajet-4mv-vacuum-hose-diagram.html

 

Lars, you really need to write a book on the Q-Jets, publish it, and then retire, living off the $$$ millions in royalties.

 

there already is a book of sort by Cliff Ruggles, more Pontiac oriented.

 

restoring the car? just send lars the carb. he doesn't just do good pics and info...

 

Transmission vacuum line comes off the vacuum fitting "tree" that screws into the intake manifold just behind the carb. Later years had the tranny vacuum line coming up to the front of the carb.
All the photos I post with the grey background are taken on my carb workbench. It's a pretty beat up workbench due to the amount of carbs and other work that goes across it, so I make sure the bench is out of focus and blends in a little... The carbs I shoot photos of for posts here on the Forum are carbs I pull out of my collection and storage area, and are sometimes customer carbs in process if I happen to have a carb in-work that applies to a tech question here on the Forum.

Lars

 

I suppose I could have sent my carburetor to Lars and avoided the following learnings, but that is not what I did, and I have a bunch of hours spent on things. Here is what happened (so far) when I tore into my newly acquired C3/quadrajet that had some performance issues.
1. Float level was too low - upon raising it to 1/4 inch (spec) I found that that "foam" float would hit the side walls of the float chamber.
The clearances were very tight and I spent a significant amount of time try to make the foam float travel up and down freely - gave up and bought a brass float. Much better and dimensionally smaller. Solved the problem (foam float would hit the side wall and not close the need/seat - carb flooded - very bad)
2. The secondaries would stick open when the engine was hot - well it turns out the throttle plates on the secondaries were not placed on the secondary axel correctly and when the aluminum base got hot and expanded, the plates would bind. I loosened the 4 screws, swapped the plates and pushed the throttle plates (gently) into the base plate as I tightened the screws. This provided a couple of thousands of side to side play when the plates were open - problem solved.
3. Incorrect fuel filter - it was a paper type and was too long, and when compressed, it would crush and reduce fuel flow considerably. I bought the correct Brass filter at Napa and the flow is much better.
4. The silly little spring clip that is attached to the float needle and hangs on the "float lever" was missing. Interesting to note, I believe without the little spring to pull up on the needle when the float lowers, the needle can actually get suck and stop fuel flow until something jars it loose. I fuel occasional fuel shortage when driving, hopefully it is fixed with the addition of the spring clip, I have not yet tried it.

 

Be aware that the brass floats are complete junk. The solder will react to the additives in modern fuel, the float will leak, and it will sink. Use a good quality NitroFill float. Not knowing what year car/carb you have I can't give you the right part number.

The paper filter is correct. If it was getting crushed you either have an incorrect backing spring or a cheap filter. Use the NAPA "Gold" filter (3051 for the short filter and 3052 for the long or a Wix filter to prevent crushing). The sintered bronze filter was not used in a Q-Jet after 1967.

 

That is interesting - The car is a 71, LS5. I can only assume the Quadrajet is of the same year. I will check out that part number on the filter.
The part number on the carb seemed year appropriate, but it could have an incorrect filter fitting as. There were some other strange things - the accelerator pump rod from the primary throttle linkage was too long, had to bend it to allow the primaries to open all the way.

Last thing, there is rust in the gas tank, which also reeks of bad gas, so it was sitting a long time. I have a new gas tank coming and will certainly clean out the line before I attempt to run it again. I am curious if rust particles could have made it through the "in tank" gas filter and clogged up the paper filter in carb.

Thanks for the reply,
Aaron

 

Have you actually looked at the sock on the tank pickup? If original they eventually break up. Concerning the in carburetor gas filter, Lars is the expert and I personally have seen the metal filter only used on Holleys, paper on all Quadrajets I have seen.

 

I have looked at the "sock" through the tank filler - it looks new. I will have it all apart in a couple of days and find out for sure.
I went through this with my 65. It also had an old grubby gas tank.

 

1971 Q-Jet should use NAPA/Echlin float part number 2-440. This float will not touch or rub in the float bowl, and it will "float correctly," which the brass floats do not. Set float level to .300" to avoid fuel seepage from the accel pump through-hole during cornering. Use NAPA/Echlin "Gold" fuel filter 3051, which is a good-quality filter made by WIX. It has good crush-resistant rigidity. Make sure the backup spring is the correct spring and not some aftermarket heavy-duty spring that is either too stiff or too long. There is only one length accel pump rod, so if you had to bend it, you have some other linkage or accel pump problem: Use of the incorrect springs on the accel pump will cause it to bind and prevent full throttle opening. Is your carb a commercially rebuilt carb, by chance..? Most "LS5" carbs I see are commercial hack jobs that have been pieced together from multiple different carbs, most of which are not compatible with the LS5 float bowl.

Interesting trivia fact: The 3051 filter (and its 3052 long-version brother) will filter out powdered sugar from the gas tank and prevent it from reaching and destroying your engine. The powdered sugar will plug the filter, but it won't go through. The sintered bronze filters will allow powdered sugar to go through. Seen it several times: In liberal woke cities and areas, people like to sabotage fun cars like Corvettes using the sugar in the tank trick. They are offended by you having more fun than they are, so they need to destroy you and your toys. You'll still have to clean your tank out to get the powdered sugar out, but it will never go through your carb or engine if you use the paper 3051 filter.

Lars

 

Thanks Lars,

I'm starting to believe that your assessment above of "hack Job" is correct. The carb appears to have been rebuilt recently but I do not know by who or what.
It did not work correctly when I got it. So I am "hacking the hack job" and hopefully it will get me by while I put other things in order. The enivitable solution is likely to get a new carb.