Cliff's Quadrajet Parts and Rebuild Kits

Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: W30Olds on May 26, 2014, 06:34:15 PM

Title: Vacuum leak at idle, hard start
Post by: W30Olds on May 26, 2014, 06:34:15 PM

Would incorrectly indexed secondary plates cause a vacuum leak at idle? make the engine hard to start? I rebuilt the carb and used bronze bushings but I believe I might not have indexed the secondary plates correctly, everything else looked fine.

Title: Re: Vacuum leak at idle, hard start
Post by: ejowrench on May 27, 2014, 03:54:02 PM

Perhaps. Place a wet rag around the secondary air valve, sealing it. If the idle does not change, look some where else....

What makes you think you have a vacuum leak?

Title: Re: Vacuum leak at idle, hard start
Post by: W30Olds on May 27, 2014, 04:22:19 PM

Its off the car now, apart. I placed a rag over the primaries when it was running and didnt do anything, then placed a rag over it with both hands sealing it and just barely changed the idle.  The engine made 18 inches of vacuum at idle warmed up, but started kind off hard. The engine was shaking and you could hear it through the exhaust, sounded like a miss or vacuum leak.

I put a reman qjet on it and it definitely idles better than the rebuilt original.

Title: Re: Vacuum leak at idle, hard start
Post by: Cliff Ruggles on May 28, 2014, 02:12:47 AM

What method did you use to install the bushings?......Cliff

Title: Re: Vacuum leak at idle, hard start
Post by: W30Olds on May 28, 2014, 04:18:56 PM

Your kit, per instructions.  Should the secondary plates show any light through them closed?

Title: Re: Vacuum leak at idle, hard start
Post by: Cliff Ruggles on June 02, 2014, 03:57:51 AM

Very, very little light when they are fully seated/closed and correctly adjusted....Cliff

Title: Re: Vacuum leak at idle, hard start
Post by: W30Olds on June 06, 2014, 09:42:46 AM

Ok, what about these defects in the main body? The first one is a hole through the first wall of the casting, right after the baffle, the other side of the secondary isnt touched. You think any of these are causing a leak?
(https://farm4.staticflickr.com/3873/14173597880_0b08fc7f9a_b.jpg)
(https://farm6.staticflickr.com/5193/14173510719_d5c6e0bf4d_b.jpg)

Title: Re: Vacuum leak at idle, hard start
Post by: Cliff Ruggles on June 12, 2014, 09:53:08 AM

Can't really tell by the pics as they are out of focus slightly.  The top pic wouldn't produce a vacuum leak, not sure about the bottom pic?....Cliff