Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Cliff making a chart

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oktorque:
Cliff, I was wondering if you ever considered making a chart of the calibrations.  Say, starting with a 350 sbc, showing the calibrations for stock and then showing how they change with as the engine is changed from mild to wild.

You could do it with several engine sizes and types to cover a broad array of builds for the public, and get it copyrighted.

I believe it would be a valuable tool.  It might also save you time and work.

Cheers. k

Marx3:
I agree that this would be a valuable tool! I guess it would balance on the edge of Cliff partly putting himself out of work :-)

I think most of what you want to know is in the book though. The book dont state if one recipe is the same for a mild 350 as for a mild 454 and this is something I have always wanted to know.
I hope you dont feel I am steeling your thread by doing this:
Here is what I have experienced so far ( based on many modifications and many many rebuilds ):

Idle air bleed is ( or should be ) fixed at .070/.070 or somewhat close to a combined total of .140
Same goes for main air bleeds. ( not on single MAB units ofcourse )

I am under the impressions that the size of the idle tubes/ DCR and the idle by pass is mostly dictated by the cam characteristics and not so much by the size of the engine ?

I am under the impression that the main fuel supply is dictated by the engine application/ performance level and not so much by the engine size? ( I think I saw Cliff mention this in a thread once, but I dont fully understand why )
Since jet size always calls for rods about .028-.030 smaller, the jet size is the only thing to speculate on when tailoring a build from scratch.   ( unless you are building an early M4M with the auxilary valve )
Please feel free to ignore all this. I am only trying to share experiences. :-)

429bbf:
i agree with what you are saying. where i see the most problems is people putting (fresh rebuilt carbs  on fresh rebuilt engines) i don't like to do this (not that i don't trust my work )the worst thing in the world is an over fueling carb on some engine  your trying to break in the cam. that said your second guessing if its the carb,ignition,vacuum leak etc. i like to take a good running carb and install on a fresh engine and tune from there . it takes a lot of guess work out of the initial startup problems.fwiw

oktorque:

--- Quote from: Marx3 on March 01, 2015, 08:50:23 AM ---
Idle air bleed is ( or should be ) fixed at .070/.070 or somewhat close to a combined total of .140
Same goes for main air bleeds. ( not on single MAB units ofcourse )

I am under the impressions that the size of the idle tubes/ DCR and the idle by pass is mostly dictated by the cam characteristics and not so much by the size of the engine ?

I am under the impression that the main fuel supply is dictated by the engine application/ performance level and not so much by the engine size? ( I think I saw Cliff mention this in a thread once, but I dont fully understand why )
Since jet size always calls for rods about .028-.030 smaller, the jet size is the only thing to speculate on when tailoring a build from scratch.   ( unless you are building an early M4M with the auxilary valve )
Please feel free to ignore all this. I am only trying to share experiences. :-)

--- End quote ---

Thanks for that Marx3.  I would add that with smaller engines QJ seeded to have .020 difference between rod and jets, for example the 301 and the 231 v6.  The 301 came with, iirc, 72 jets and 52 rods, whereas the 231 had 67 jets with 47 or 48 rods. 

Cliff's Chart:  I read Cliff's post about not having time to answer posts nor emails or even the phone.  The business has expanded to the point he needs to hire someone, or keep it a one/two person small business side line.  Of course his decision will dictate the future of his sales.  Without support interest and subsequently sales will dwindle. 

Take the forum for an example.  It become virtually useless without Cliff answering questions.  Posts go unanswered.  Customers stall in projects.  We all admire Cliff for his expertise and need his knowledge.  But without a highly qualified overseer contributing to the forum it is virtually useless.   

Marx3:
I think you are right... This forum kind of revolves around Cliff's answers, BUT there are others in here, that are capable of giving thrustworthy answers too. I have been a member for a handful of years and I seem to remember at least 3-4 users, other than Cliff, that clearly knows what they are talking about, when it comes to suggesting calibration.
I dont clame to be one of them ( not yet at least... I need another season of building Qjets to get some more hair on my Qjet-chest )

This forum is invaluable, but sadly it is pretty slow.

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