Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

'78 Pontiac L78 carb - stumble at idle and mid-range

<< < (2/3) > >>

Cliff Ruggles:
Did you use one of our rebuild kits?

If so it would have had a new secondary cam/spring in it.

Did you remove or at least clean the idle tubes during the rebuild?

The only way you are doing to detect a small leak at the bottom plugs is to pressure test them.  This procedure is described in my book......Cliff

KeithinMI:
Cliff,
Bought your book long ago. Carry the .pdf of it all the time, since I bought the digital copy.

Unfortunately I did not get the kit from you. It was a kit I purchased prior to my first carb I sent to you a bit over a year ago (which you did a great job on, btw!)

Did not get a secondary cam or spring with the kit that I had, but it did have the accel pump with the blue gasket and garter spring.

I did clean everything in the carb including the brass tubes, and the air transfer passages. Made sure I blew out everything with compressed air after rinsing everything with brake cleaner after the soak in carb cleaner bucket.

Cliff Ruggles:
Did you remove the idle tubes from the main casting and manually clean them? Blowing them out will NOT remove any of the "varnish" inside them from many drying up cycles.

"Blue" seals mean nothing, every single one we tested no matter where we sourced them out failed in this new fuel, sooner or later.

Your kit will not have had the correct high flow .135" N/S assembly in it either, which effects the fuel level at any given pressure.  This also effects fuel delivery at all levels as well......Cliff

KeithinMI:
couldn't edit the post above for some reason:

Did not remove idle tubes. Looks like she will be coming apart again. Do I remove the tubes from the top or do I need to remove the throttle plate to get them out? Will they come out with the crimped on collar?

I'll need to order a proper accelerator pump, secondary cam, and spring from you, as well as a .135 needle/seat

I'll get the proper carb number tonight.

Cliff Ruggles:
The idle tube removal procedure is described in our book.  Basically you will need to drive the tubes down slightly and pull the collars out of the castings.....Cliff

Navigation

[0] Message Index

[#] Next page

[*] Previous page