Tim305

350 cutlass edelbrock intake , carb bought as a rebuilt from rock auto. Engine idles a little rough. My question is this? I turned right side idle screw in until it ran rough the opened it up 1 1/4 turns. I turned the left side in all the way and there was no change in the engine. I opened it out several turns and no change. This does not seem right. Should there not be a change ? I should note that the car seems to run fine just idles rough

Tim305

Ok so nobody knows anything about quadra Jet carburaters . Should have bought a holly I guess

jcdynamic88

there definitely should be a change when turning the mixture screw all the way in,maybe even stall. remove that screw and spray carb cleaner in the hole and compressed air if possible.it's worth a try before returning it or having to take it apart

61reoldsman

I would guess you have a vacuum leak somewhere around the engine . Idling rpm will make it more prominent then cruising. I always tune with a vacuum gauge to the highest reading that is possible.

Erinyes

I'm pretty sure there are quite a few people who know quite a lot about Quadrajets on this site, but a little more info would be useful. Why a new carb in the first place? Were there existing problems that you hoped a new carb would resolve? What kind of engine specs? Stock, with an Edelbrock intake? Which intake? How worn is the engine? How many miles?

Speculating on why one idle screw isn't changing engine rpm without more info is just that, speculation - although 61reoldsman has a good suggestion, which you can check by spraying the intake gasket, carb gasket, carb throttle plates, EGR valve (if equipped), clamping down on vacuum hoses, etc.

Tim305

The engine was rebuilt about 5000 miles ago by the po (college auto shop) . It had a two bbl carb. I installed an edelbrock intake and the 4bbl why? Cuz I wanted a 4bbl. It runs strong just idles rough. I've timed it every which way but can't get the idle smooth. I should also note that I left the choke unattached. I didn't want to mess with installing an electric choke and I don't need it. I am thinking I probably have a leak somewhere on the intake after reading the above. I'll try the carb cleaner in the hole with the air. Then I guess I'll need to remove the intake.

76olds

Tim if you used the rubber end seals then I would check for leaks around those front and back of the intake. Also the 3711 and 2711 intakes usually leak around the base of the carb. Did you use a spacer under the carb or just bend up the throttle linkage to clear the intake? I had used a 2711 intake in the past and had to put some silicone under the rear of the carb just ahead of the rear bolts.
Hope this helps
Eric

Tim305

I did not use the rubber end seals since my research suggested not to. The intake is the 2711. I tried to spray around the intake to try to spot a leak but never checked the carb I'll try that thanks. The engine runs so darn good going down the road, lots of guts, only problem is the bouncing idle.

76olds

Good to hear its running strong, If you do find its leaking at the base of the carb and its not a vacuum hose or carb issue, I would look into putting a 1" 4 hole spacer under the carb , they are inexpensive and you likely feel a little more low end torque. Not anything crazy but worth the install. Then put a little silicone on the base of the spacer ahead of the intake carb bolt holes. You will feel the vacuum leak with the spacer for sure .
Hope this helps
Cheers
Eric

olds 307 and 403

I assume it idled smooth with the two barrel? A lot of the reman Qjets have had a lot of issues. Either a rebuilt from a Qjet expert or a Street Demon 600 or 750 cfm carb is the best choice for a cruiser. The Street Demon is based off the Thermoquad in an all new 3 barrel castings.

Marx3

it sounds like something is off internally, in that carb. Is the carb set up to some kind of performance level? I dont know Jet's reputation, but as 307&403 says, alot of those "new" shiny Qjets are poorly built and calibration is all over the place.
A well-calibrated Qjet will never give you those kibnd of problems.

Tim305

I located the leak thanks to you guys. It was between the edelbrock 2711 intake and the carb. I am amazed at how well the thing runs with the size of the leak I found. I am going to try 76olds suggestion and get a spacer since I got to take off the carb anyway. Silicone sealer? Would that be like permatex or is there a special type sealer I need? I can't tell you guys how much you have helped me here and elsewhere on this site. I recently retired and am living my dream. Sometimes my dream overshoots my ability however.

olds 307 and 403

As long as gaskets are used on both sides of the plate, you should be fine. If you insist on sealant Gaskasinch or Permatex Aviation sealant brushed on would work.