hudman

For those of you that have been helping me with my "problems", they never seem to end. A refresher for those that need it. I had the motor rebuilt this winter/early spring. Everything is new or reconditioned except the carb (Edelbrock 1901 Qjet replacement) and the stock distributor.

I now have about 475 miles on the new motor. Upon reinstallation, I had huge idle problems caused by vacuum leaks associated with having the wrong carb base gasket. Lars hooked me up with the correct three piece gasket. That fixed the vacuum leaks at the base, but I still had a bad leak at the throttle shaft and the car developed a bad surge at cruise. It was almost like plugging one leak caused another one. After much debate on the Forum regarding the surge, Tom454 who is in the same town kindly agreed to rebush the throttle shaft for me one Saturday which promptly fixed the throttle shaft leak and the surging. Car ran better than it ever had since I owned it. It would hold its idle perfectly, more responsive than ever, etc.

Several months have gone by and several hundred more miles, and the carb still just did not seem right. The idle mixture screws are not very responsive, there is some black smoke at WOT, etc., so I planned on sending the carb to Lars for a rebuild later in the summer. I do not know what is in this carb, so I figured I would allow him to get it back to stock configuration.

Well, I do not think I can wait any longer. The car is not driven often, but the last two times that I drove it it is knocking off on me after heavy acceleration. It idles fine after start up and runs fine if you accelerate lightly. But after romping down on it in most any gear, if you depress the clutch or take it out of gear, it will die. If you leave it in gear, you can tell the car is trying to die, but the only thing that is keeping it running is the fact that it is in gear. When you push in the clutch, it does not drop to idle, and then stumble and die, it drops straight to 0.

What could be causing this?

Matt Gruber

What is happening now?
i assume you are boxing it up and sending it to lars. :yesnod:

Hobbes Blk '80

What does Lars usually charge for a Q-Jet Rebuild? I am sure he can put them back together a little better than stock, right? ;)

Mine is in trouble, and I am planning on doing some wild rebuilding this winter... :thumbs:


[Modified by Hobbes Blk '80, 3:36 PM 7/7/2003]

Boofers

Sorry to hear about your engine troubles! Sounds like it could be a number of things. Maybe you are running your secondaries way too rich. Could be your secondary air plates are set to open too easily. Your float may be set too high. Your needle may not be closing all the way in the seat. Do you notice any flooding or gas dribbling out of the carb anywhere?

I assume your timing is set properly. Some timing problems can diagnose like carb problems. Make sure your mechanical advance is free.

One of the best tools I ever bought was a combination vacuum guage/fuel pressure guage. It told me a lot about my engine. Everyone should have one.

Good luck, hope to hear what you find.

Oh ya, these might help you out too:

http://www.buickpartsdirectory.com/carbs.htm
http://www.corvettefaq.com/listing.asp?group=1&sub=11
http://www.carbs.net


[Modified by Boofers, 10:00 AM 7/7/2003]

hudman

Given that these problems surfaced on their own (ie. not as a result of any other modifications) and because I have not been playing with anything else like timing etc., I have to assume that it is carb related.

Carb will be removed and shipped in a matter of days.

Tom454

Probably a good idea getting it rebuilt. But if you want to try it on my 454 again... I'm game. The last time we did it, the carb ran fine on my car, but not on yours. Also.... if you do send the carb off... in the mean time, you should bring your distributor over so I can take a look at it.

lars

hudman -
If your carb is running fine on Tom's car but not on yours, you probably don't have a carb problem... I always tell people that 90 percent of the carb problems I see are ignition problems, so I'd take Tom up on the offer to go through the distributor first. Once the distrib is tight and verified good (properly working centrifugal advance & vac advance), then move on to the carb - give it another test run on Tom's to see if the problem is really there. I receive quite a few carbs for rebuild that actually don't have any problems - the problems are in other areas of the car.

hudman

Tom and I are going to get together on Saturday hopefully. I greatly value his opinion.

There just seems to be a progression to this thing that "feels" like a carb problem to me, but what do I know? First, car is running fine, but idle mixture screws are ineffective and I have smoke at WOT. Then a few weeks ago, the car develops an occaisional stumble under modest acceleration. That has escalated to the current condition of frequent stumbling and shutting down, generally a crappy running car. Absolutely no fun to drive.

Tom has suggested the water in the fuel tank issue, but I have had that problem and it does not feel the same to me.

I guess it is time to start ruling out things one by one. . .

Brettmc

:iagree: Sounds like good advice.

Brett :thumbs: