Have the original stock Quadrajet on my 71 350/270hp turbo 400. I think it needs a rebuild. Idles high, 12 to 1500 rpm’s. Choke doesn’t kick down when engine warms up and the secondaries don’t open all the way at WOT…

Today when I get in the Vette my gas pedal seemed to be getting stuck on something. It wouldn’t go down all the way when pumping the gas. I though the cable was catching somewhere but when I took the air filter off I discovered the linkage barely moved even moving it by hand… It’s happened to me a couple times but I was always able to free it up by stomping on the pedal a few times. Today it wouldn’t free up… After fiddling with the linkage on both sides for a while I gave it a final stomp on the gas pedal it suddenly freed up and moved easily. I hopped in and started it up to find the idle even higher. Drove to an event I really wanted to attend today at the race track anyway and aside from the high idle it drove great. Once at the event I shut it off and it sat for a while. When I went to start it again I got a huge backfire, sounded like an M80 if you know what that is, and it was smoking a lot from the exhaust pipes… Thought I blew up the motor. The motor still ran ok but was smoking a lot from overdose of gas. I tightened down the gas/air mixture screws and backed them off only one turn. That got things to normalize and I was able to drive it on the track where the event was happening, actually ran pretty good. On the last lap I noticed my breaks were getting soft. I thought ok now what… checked the master cylinder, levels were good. Then noticed the vacuum line from the booster to the back of the carburetor was lose… tightened that up and got the brakes back but I think the base plate may have a crack in it where that bolt goes in. So it was another exciting day 🤪.

My plan is change the carb to a Holly doble pump ( 600 or 650 maybe or what ever would be best for my Vette ) and rebuild and store the Quadrajet… Just seems like all my problems stem from carburetor. I wish Lars was in Spain.

If you made it this far, any thoughts on my long story are appreciated… Any suggestions on a new carburetor would also be welcome…

PS, as if this post wasn’t long enough already. I ordered some long tube headers and am thinking as long as going to change the carburetor I might as well change the manifold too. I don’t want to modify or change the hood though. So any suggestions of a manifold and carburetor combo to complement the headers are also welcome. I will keep and store all the original parts of course.

Sorry for this long post…

attached video is from today’s event

 

Keeping these old cars running well here, is getting harder all the time. Crappy parts, lack of knowledgeable mechanics, etc. Keeping one running well in Spain must be 100x's worse.
There is usually nothing to be gained by going to a Holly from a GOOD Q-jet. The problem is that you can't get a new one, and many rebuilt ones are not correct. But parts, instruction manuals, quality rebuilders, are available. In your case, it may be easier to go the Holly route.
I think you have to buy a new intake manifold for the Holly double pumper.
In the short run, have you tried running some carb cleaner in your gas. It sometimes helps.

 

No, haven’t tried that, imagine if that’s all it is… Could easily be some gunk in the carburetor getting things stuck. 🤔

Will give it a go…

 

I think I would rather rebuild your Quadrajet than replace it. If something is sticking, give all the moving parts a good look over. Is this still your same setup?

 

Time to get in touch with Lars on this forum if the carb is the original.

 

Yes, that’s my set up, nothing has changed…

 

Yes it is original….

 

Stomping on a gas pedal connected to a throttle linkage that is jammed is an excellent way to break or bend something.
Get the factory Chassis Service Manual and Overhaul Manual for your car and read the sections on carburetors. Get a rebuild kit and DIY.

 

A lot of people love quadrajets here. Nothing against them.
But my vette sure does run great with a Holley DP lol

 

I know this may sound a little blasphemous, but for a little over $200, you can buy a brand new Chinese quadrajet clone including shipping. I bought one last year and it worked perfect right out of the box. A lot of brand name stuff comes from over there anyway whether you know it or not.

 

Try tightening the carb bolts? Tighten with a screwdriver socket as tight as you can should be about right..idle high sounds like vacuum leak?
slowly have someone travel the throttle while you observe for any issues

 

First thing I would do is disconnect the throttle cable and make sure it works through its full range of movement without binding. If the vacuum hose for the brake booster was loose this would have screwed up your carbs settings, if you’ve eliminated any vacuum leaks I would then put the carb settings back to where they were if it ran satisfactorily in the first place. From there if it’s not running well did you by chance get any fuel that might have been contaminated with water or the like? As for manifolds Weiand make a street warrior version that can fit spread or square bore carbs and so far is the lowest profile dual plane alloy manifold I’ve found apart from the old Torker single plane.

 

Dave
Have you thought about sending the carb to Lars and having him rebuild it, he is a Pro? You won’t have to change the manifold and it will keep the car original. I also bet it will also be less expensive!

 

While it was suggested above to send the carb to Lars, I'm sure that would be a helluva undertaking from Spain, but how about corresponding with him and seeing if you can get your problems worked out on your Qjet. He's been very helpful over emails that I've sent to him. I'd bet he'd be willing to try to help you out.

 

Going from a small headache to a huge one. Lars wouldn't touch those "knock-offs" if he had to. Too many issues.

Sometimes you just got to bite the bullet and buy a new Intake and a Holley.

 

I would be happy to do that but how long will my car be off line.., Ild like to get a Holly or Edelbrock that will bolt on to my original intake so I can use my Vette while Lars does the rebuild if he would be so kind to take my money and do it…

 

email Lars and ask him, v8fastcars@msn.com

 

Would this be the correct kit to buy? This is from Summit:

JET Carburetor Rebuild Kits 201003

 

No. Contact this company
https://cliffshighperformance.com/pr...uild-carb-kits

 

wrote to Lars…🤞