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67cruiser · 01-26-2009, 10:55 AM

Well ive read Cliff,s book about 5 times now and find myself confused somewhat on this issue, here,s what i mean, On page 32 Mr. Ruggles explains very nicely in detail about main air bleeds and its fuction and the control of air and fuel to the nozzles, great job to. Then turning to page 94 in the picture he states DO NOT ENLARGE THE AIR BLEEDS BUT DO RESIZE IDLE TUBES. Then under his recipes he calls for .070 main air bleeds in the main body under first recipe. Most q-jets ive seen main air bleeds are close to .040. so do i enlarge them or not?? I am just a little confused, anybody what to help me out a little.

chiphead · 01-26-2009, 02:39 PM

This confused me as well for awhile. What I realized is that there are IDLE air bleeds for the idle system and MAIN air bleeds for the main circuit. Make sure the hole you are looking at is a MAIN or IDLE air bleed, and don't get them confused.

The size of the Idle and Main airbleeds depend on carburetor year and application, and varied widely. Post the carb number and we can tell exactly what the stock setup was.

On page 32 he is showing pics of the MAIN airbleed system. Page 94 does confuse me. He is discussing mods to the idle system on pages 93-96, but I believe the picture on page 94 shows a main airbleed location? Maybe Cliff can enlighten us.

Cliff R · 01-26-2009, 02:49 PM

I'm always confused!

Go to page 27, both upper idle airbleed locations are shown in the pics.

Go to page 96, the pics show the location of the lower idle airbleeds (left pic), and the upper idle airlbeeds in the main casting (right pic).

Go to page 119, both pair of upper idle airbleeds are show (lower right pic).

There are also several other pics referencing upper idle airbleeds in the airhorn, which were used on some 1975 and earlier models.

Bottom line, you can only have one pair of upper idle airbleeds, they must be in the main casting just above the idle downchannel restrictions, or in the airhor just above them, not in both places.

The recipes use different sizes as the idle airbleeds in the airhorn are "direct", the idle airbleeds in the main casting are "indirect". Hope this helps some......Cliff

67cruiser · 01-26-2009, 05:20 PM

Helped me out somewhat, ask a question here always get great answers! confusing still a little, but ill figure it out.Im sure we will get more opinions in days ahead, Thank You Cliff, did help .

Region Warrior · 01-26-2009, 06:20 PM

Now i'm confused...gon'a have open one up and have a look see.

BTY, does he?

67cruiser · 01-26-2009, 08:40 PM

I see another on page 32 lower right hand side main air bleeds, Is this the one that should be .070 in recipe no. 1??? This is where the confusion is coming in??

Kenth · 01-27-2009, 05:33 AM

Yes, picture on the right shows main air bleed (main body) and picture to the left shows main airbleed (air horn).

Picture above these shows main airbleed for single main air bleed carbs, (no main airbleed in body).

67cruiser · 01-27-2009, 09:54 AM

Keith, The carb. im working on 7027262 has small air bleeds about .046, idle channel restric. are at .056, 71 jets idle holes for screws are at .090 street car, going on a 68 firebird. Main Air fleeds on this carb. are at .055, thats why i want to make sure to open them up to .o70
Thank You.

Kenth · 01-27-2009, 12:33 PM

Those numbers doesn´t seem right for a 7027262?
All i have seen would have .040" upper idle airbleeds and .070" main airbleeds in both airhorn and body.
Also idle cannel restriction seem way big for an original unit with this #, would be in the .046" range?

My guess is that your carb has been thru a "remanufacturing" process at f.e. Holley?

Cliff R · 01-27-2009, 06:53 PM

Agreed, without exception all of the 67 Pontiac carburetors from V-8's I've seen have small upper idle airbleeds, and .070" main airbleeds, as Kenth mentioned.

A few Buick and Old's carburetors from that period will have specs closer to what you have mentioned.....Cliff

67cruiser · 01-27-2009, 08:46 PM

Bought a 3 ft. section of tig rod today, will cut a piece and get it into channel restriction and reduce size down to .040. Thanks Guys

67cruiser · 01-27-2009, 10:13 PM

Tig rod pieces are now intact, idle channel restrictions drilled to .046 lower idle air bleeds is at .070

Cliff R · 01-28-2009, 08:20 AM

I'm now confused more than ever. How did the lower idle airbleeds get involved in this discussion?

I read that you were working with the upper idle airbleeds and the main airbleeds. It would be quite rare to see any modifications to the lower idle airbleeds, even after a "butcher" job by one of those commercial rebuilders.

They will almost always drive thick brass restrictions into both pairs of main airbleeds, and install larger idle tubes, and sometimes drill the idle downchannel restrictions to excessive sizes, but to date I've only seen one that had mods to the lower idle airbleeds.

What exactly did you end up with for the following items:

idle tubes
lower idle airbleeds
upper idle airbleeds
idle downchannel
idle bypass air (if used)
lower main airbleeds
upper main airbleeds
jet size
metering rod size

67cruiser · 01-28-2009, 02:05 PM

I believe lower idle air bleeds never got into the talk Cliff, I just wanted to say the size they where, Main idle system where i was asking questions. Hope this clears this up.

67cruiser · 01-28-2009, 02:14 PM

Forgot to mention, Bypass hole of .070 is already in base plate nothing in main body, top section has slots cut into them. idle tubes set at .036 idle channel .046 Lower idle air bleed is .070, upper idle air bleed is at .067 Secondary fuel well opened up to.036 jets that was in the carb. are .070 with a .040 rod, main air bleeds are .070. Sorry for any confusion.

Cliff R · 01-28-2009, 03:08 PM

If the upper idle airbleed is in the airhorn, .067" is pretty big. Most of those carburetors I've seen had really small upper idle airbleeds in the airhorn, not in the main casting. Nearly as I can remember they were around 040", and combined with really small idle tubes.........Cliff

Kenth · 01-28-2009, 04:37 PM

Quote:

Originally Posted by 67cruiser

Forgot to mention, Bypass hole of .070 is already in base plate nothing in main body, top section has slots cut into them. idle tubes set at .036 idle channel .046 Lower idle air bleed is .070, upper idle air bleed is at .067 Secondary fuel well opened up to.036 jets that was in the carb. are .070 with a .040 rod, main air bleeds are .070. Sorry for any confusion.

This is getting worse....1967 Pontiac Q-jets did not use idle bypass air and .067 upper idle airbleed in airhorn is way big.

I´m not sure if your carb is put together with matched airhorn, float bowl and throttle plate at all?

Some pictures and some cast numbers on parts would help?

67cruiser · 01-28-2009, 06:14 PM

Maybe just maybe you guys did not read my answers, the 67 carb. does not have bypass, i stated the provisions are there a .070 holes in the base plate, nothing in the body and it has the slotted top to the carb. and i did ad a small piece of tig rod to the carb. and drilled the idle restictions to .046. Thanks again for your input and answers.

Cliff R · 01-28-2009, 06:57 PM

Idle bypass holes in the baseplate, wrong baseplate. Main casting not drilled through for bypass air, that's OK, but having holes in the baseplate isn't doing you any good. Airhorn has the notches for bypass air, that's OK too, but still means nothing on the undrilled main casting. .067 upper idle airbleeds, in the airhorn, are too larger for that set-up.

I agree with Kenth, sounds like the carb has miss-matched components, and the calibration is off some as a result. High probability the carburetor has been commercially "remanufactured" at some point.......Cliff

67cruiser · 01-28-2009, 09:02 PM

May i ask this, wize to go ahead and ad bypass by drilling out the main body or i can just drill the holes and ad set screws to them on the baseplate. Again the upper air bleeds are now at .046 in the airhorn.

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