Cliff's Quadrajet Parts and Rebuild Kits

General Category => Quadrajet Carb Talk and Tips => Topic started by: Albert on March 17, 2026, 04:59:32 PM

Title: Bigger holes in Main body and Air Horn than First Recipe recommendation.
Post by: Albert on March 17, 2026, 04:59:32 PM

Hi All.
I hope I posted this in the correct place.
I bought Cliff's service kit. His advice, and reading on the forum here has been a God-send!
I have measured all hole sizes in the body and air horn of my current (and first) attempt to restore a this Quadrajet which will go on to a stock standard AMC 304 V8.

Do I need to reduce some holes sizes to suit the 304? The holes in the castings, are larger than what Cliffs First Recipe recommends.

Particularly: Idle channel hole, Upper Idle Air bleed, Accelerator Pump discharge holes, Secondary POE Well restriction, and should I reduce the Secondary Air Flap Opening Distance.

I have highlighted these items in red on the document that I will try to attach below, and a couple of photos of where I am at for now.
First column next to descriptor is my Carby, to the Right is Cliffs recommended First recipe for comparison.

Would it be OK to pop it onto the engine and try run & tune it or will these specs just not work?
I look forward to hearing your thoughts.
Many thanks.


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Title: Re: Bigger holes in Main body and Air Horn than First Recipe recommendation.
Post by: Kenth on March 18, 2026, 02:39:34 AM

You may open the idle channels to .046".
The upper idle air bleeds, .069 are located in the float bowl (not in the air horn) and is on par with Cliff´s rcommendation.
The accelerator pump discharge jets, .026" are located further in thru the outer .060" siphon hole.
The .040" secondary POE well restriction is fine.
The secondary POE discharge jets, .030", are located further in thru the .053" holes. Needs to be opened.
Doesn´t hurt to increase the secondary air valves opening angle.
If you are using an electric choke element and plug the hot air channel, you may want to add some idle bypass air in the throttle plate, .070"-.080" for each bore will do.

HTH

Title: Re: Bigger holes in Main body and Air Horn than First Recipe recommendation.
Post by: Albert on March 18, 2026, 06:06:50 PM

Thanks for your quick Reply Kenth!

I had another look, and re-read, and I think I got the correct locations as you describe.
I attach some images of Pin Gauges / drills popped into the locations.

I will appreciate confirmation that I have correctly identified them all, please.

I do not want to drill anything until I am absolutely sure I have identified the correct items, and that they

NEED to be drilled for the engine to run correctly.

• Idle Channel (- Are these also Called Down Channels?) Do I need to open these up, or is it a might need?
  Should I try run the engine first, then see if it needs opening?
• Upper Idle Air Bleed in Main Body. They are at .069"
• Accelerator Pump Discharge Jets are at .026"
• Secondary POE Well restriction is actually at .039" - not .040" - will that matter?
• Secondary POE discharge jets are at.030" - is this a need to enlarge to .052"? Bearing in mind its only a 304 engine this is going to sit on.
• I'll leave air flap distance as is for now, and see how it goes when I run the engine.
• If I find I need more Idle Bypass Air, where do I drill the holes, and should they be in the primary throttle plates? (I am using electric choke).

Many questions I know!

Below are my Images to help make sure I have got things right before I start to make "permanent" changes to my Carby.

I look forward to your advice  :)

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