Thermoquad vacuum leak at base

[hsb shadow]

I installed my rebuilt thermoquad and it appears to have a vacuum leak at the rear passenger side of the car. I have switched base gaskets. If you cover the mouth of the carb the RPMs pick up and it smooths out. Any suggestions. I have friends that have told me they've had a heck of a time sometimes intake

 

[hsb shadow]

I checked the intake with a straight edge and it appears to be true. The base of the carburetor doesn't appear to be warped.

 

[Challenger RTA]

Soke the gasket with WD 40. Spray on and let it sit. Then install when it seems a little softer.

 

[Ricks72Chlgr440]

I installed my rebuilt thermoquad and it appears to have a vacuum leak at the rear passenger side of the car. I have switched base gaskets. If you cover the mouth of the carb the RPMs pick up and it smooths out. Any suggestions. I have friends that have told me they've had a heck of a time sometimes intake

Did you spray that back corner or other parts of the carb base to determine there is a leak? Putting your hand over the carb richens the mixture but does not necessarily mean there is a vacuum leak. There could be other issues making the system run lean.

 

[hsb shadow]

I sprayed your car circumferentially and it's the passenger side with the leak. There appears to be very tiny leak at the throttle shaft but the sizable one at the rear. The RPMs pick up and briefly the motor smooths out following the application.

 

[hsb shadow]

I'll pull the gasket off tomorrow and soak it in WD-40 and we'll see if that softens in enough to get a better seal. I appreciate all the advice. I think this car doesn't want me to finish it after three and a half years of restoration. LOL

 

[Ricks72Chlgr440]

I sprayed your car circumferentially and it's the passenger side with the leak. There appears to be very tiny leak at the throttle shaft but the sizable one at the rear. The RPMs pick up and briefly the motor smooths out following the application.

I was going to resurrect my TQ but decided to go a different route. You might want to contact the folks at QuadrajetParts.com to get the throttle shaft bushing kit they sell to fix the throttle shaft issue.

 

[elan71]

I used this one to repair mine:

Throttle Shaft Repair

Throttle shaft repair tools for Quadrajets and TBIs

throttleshafttools.com

Works perfect and is very easy to use.

 

[Challenger RTA]

This guy shows it cut and dry and done. Not a big deal

 

[Ricks72Chlgr440]

This guy shows it cut and dry and done. Not a big deal

It really is important to deal with those OE shafts like that. Leaking fuel and vacuum leaks there need to go away!!!

 

[Xcudame]

Bushing on the Thermoquads do seem to wear out after 50 years or so. Relatively easy to repair as mentioned above. What base gasket are you using? I really dislike the thin ones as they tend to leak more often than not. I prefer the ones that are 1/4" or so thick.

 

[hsb shadow]

I think that might be my next step if my current solution fails. I really didn't see much throttle play when I examined it. I got some fuel resistant gasket material and went back to the 1980s and custom cut my own gaskets. I'm going to stack two of the softer gaskets on top of the hard base gasket and see if it seals. The greatest increase in RPM occurred at the back part of the carburetor on the passenger side.

 

[hsb shadow]

I have rebuilt a few quadra jets in my time. I had every one of those rebushed because they fail miserably. LOL

 

[hsb shadow]

I believe my base gasket is quarter inch. I did try the thicker one but it really didn't seal much better. Rather than soaking the gasket in some petroleum based product I decided I would try to put a softer gasket on top and see if it would seal

 

[hsb shadow]

Thanks for all the suggestions