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 Throttle clearance inspection 
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Joined: Tue Aug 23, 2016 10:38 am
Posts: 84
I have seen is listed a few times that rochesters have more throttle shaft clearance than other carbs. At what point do you consider it necessary and how do you inspect it? Dial indicate to shaft vertical movement on drivers side just outside the base plate?


Thu Sep 15, 2016 1:33 pm
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Joined: Tue Aug 23, 2016 10:38 am
Posts: 84
Well since I am spending so much time to get this carb nice I will just do it. Suggestions on where to get a kit?


Mon Sep 19, 2016 8:19 am
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Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1744
Years ago I pondered getting one of the "bushing installation kits" but haven't bothered because if you look close the bore for the throttle shaft is counter-bored 11/32" deep enough on each side you can use brass model shop tubing to make bushings without drilling or reaming anything. 11/32" OD x 5/16" ID brass tubing is available at most hardware stores, probably wherever you are buying the tubing to make the secondary comp/cap jet discharge tubes.

You can also use the Holley vacuum secondary shaft bushings, the nylon strips, if you trim them a bit. A combination of the nylon strips and a brass tube bushing to retain them will cut the leakage down to a dull roar.

The deal with the bushing kit is the piloted reamer or drill bit will follow the worn hole and the new bushing location will end up out of whack with the T-slot locations. A local guy was doing this to every QJet he rebuilt whether it needed it or not, and he always got the shaft crooked in the base so one butterfly was lower than the other or the primary side was too low and too far to the rear, at least the ones people brought to me to fix. If you think you need to do this you need to be very meticulous in the setup in the mill or drill press so the shaft axis remains true.


Mon Sep 19, 2016 3:41 pm
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Joined: Sat Aug 24, 2013 7:57 pm
Posts: 157
Location: Frostburg, MD
K&S Precision Metals has 11/32" x .014" tube. [.316" i.d.] #8134 is 12" long. Apx $6 shipped on ebay.


Mon Sep 19, 2016 8:48 pm
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Joined: Fri Oct 23, 2015 8:43 am
Posts: 33
I've bushed a few using the common bushing kits and a hand drill, and I've never noticed a problem with the transfer slots being un-even side-to-side. HOWEVER - the ones that I have bushed were not extremely worn, so I think the pilot on the "bushing kit" drill did a pretty good job of locating the hole for the new bushing. If you had a carb with a lot of wear, I can see where this would be an issue.

The tool I used pilots off of the shaft bore between the primary throttle blades. Hate to say where I got it (Only because it is from the same guy that wrote the "recipe" book that is not popular around here).


Mon Sep 19, 2016 8:54 pm
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Joined: Fri Feb 08, 2013 2:37 pm
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You know how things are not always what they seem? That 'recipe' book to which you may be referring to has some popularity around here because it gives us an opportunity to rehabilitate QJets that have fallen victim to the "drill baby drill" recipes. I reckon it is somewhat unpopular with its victims after they figure out they are, but after folks get over whining about how much more difficult it is to drill holes smaller than larger, they emerge with a smile, clean plugs, clean oil and 20 MPG, plus awesome secondary action with full-on WAAAA, no more bah....uhh...aaa.


Mon Sep 19, 2016 10:09 pm
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Joined: Fri Feb 08, 2013 2:37 pm
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dave brode wrote:
K&S Precision Metals has 11/32" x .014" tube. [.316" i.d.] #8134 is 12" long. Apx $6 shipped on ebay.

That's harsh unless it is for 3 or 4 tubes. The local Ace Hardware has it a lot cheaper. I think a 3 foot length is about that much. It's been a while since I bought several so maybe (probably) it has gone up.


Mon Sep 19, 2016 10:19 pm
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Joined: Fri Oct 23, 2015 8:43 am
Posts: 33
tuner wrote:
You know how things are not always what they seem? That 'recipe' book to which you may be referring to has some popularity around here because it gives us an opportunity to rehabilitate QJets that have fallen victim to the "drill baby drill" recipes. I reckon it is somewhat unpopular with its victims after they figure out they are, but after folks get over whining about how much more difficult it is to drill holes smaller than larger, they emerge with a smile, clean plugs, clean oil and 20 MPG, plus awesome secondary action with full-on WAAAA, no more bah....uhh...aaa.


I can't argue with that. I don't follow the recipes (learned my lesson), but combined with the Roe book, I think the "recipe" book is still a decent resource for someone that wants to start playing with these carbs, so long as you don't do all the drilling it suggests.


Tue Sep 20, 2016 7:08 am
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Joined: Tue Aug 23, 2016 10:38 am
Posts: 84
I like not drilling the body. Plus using tubing saves me quite a bit on a kit.

I found this while looking for how to tell what is an "allowable" clearance.
http://rmcavoy.freeshell.org/Q_Jet_bushings.html
Interested in what you guys think.

On a side note, unless someone tells me a better place I was going to purchase a master kit from the "recipe" fellow.
Even though he may have a poor idle system mod is kits include a lot of parts that are semi difficult to get or are hard to get in a kit.

I have the Cliff book as well as a new version of the Roe book and a 73 copy. Despite the "recipe" part Cliffs pictures helped me understand the carb. I used them all in concert. My new Roe Copy is a Chinese copy and a much smaller size. Makes the pictures hard to see. Plus I am sure it is a copy of a copy sort of thing. The Dog eared 73 version of the Roe book included a lot more information on the 2G that was useful this summer as I was making the best of what I had with the current 2bbl. Allowed me to greatly improve the power while adding mpg (from 13.5 to 16). Makes me fell a little bad it will most likely go in the trash when the 4bbl goes on.


Tue Sep 20, 2016 9:59 am
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Joined: Sat Jun 21, 2014 5:38 pm
Posts: 17
80427 wrote:
I like not drilling the body. Plus using tubing saves me quite a bit on a kit.

I found this while looking for how to tell what is an "allowable" clearance.
http://rmcavoy.freeshell.org/Q_Jet_bushings.html
Interested in what you guys think.

On a side note, unless someone tells me a better place I was going to purchase a master kit from the "recipe" fellow.
Even though he may have a poor idle system mod is kits include a lot of parts that are semi difficult to get or are hard to get in a kit.

I have the Cliff book as well as a new version of the Roe book and a 73 copy. Despite the "recipe" part Cliffs pictures helped me understand the carb. I used them all in concert. My new Roe Copy is a Chinese copy and a much smaller size. Makes the pictures hard to see. Plus I am sure it is a copy of a copy sort of thing. The Dog eared 73 version of the Roe book included a lot more information on the 2G that was useful this summer as I was making the best of what I had with the current 2bbl. Allowed me to greatly improve the power while adding mpg (from 13.5 to 16). Makes me fell a little bad it will most likely go in the trash when the 4bbl goes on.


Roe's book is very good but doesn't go in to much detail on how to modify the the idle circuit. I've found that Tuner's idle air bleed mod has worked flawless on the last few carbs I've done. He should write a book! Ruggles' book is very good but like you and everyone else has said his recipes tend to open things up too much especially on the idle circuit. I've bought his rebuild kits and they are good quality. They are expensive and I use them when I'm doing an all out performance modded carbs. For stock rebuilds I like to use parts from Quardrjet.com . There quality is good and a little cheaper but Ruggles gaskets seem to be a little better and thicker.
Rebushing throttle shafts...... Well here is my take on this. Back in the 90s I bought a rebushing kit for like $80. When I first saw them for sale I thought there was no way they would work with a hand drill. I even had an old German machinist buddy of mine tell me "no way you will get them straight with a hand drill", but after finding more and more worn throttle shaft I decided to order the kit. It showed up and all it had in it was some brass bushing and a 3/8" x12" long drill bit that was ground down to 5/16" for about 2". I was skeptical. I dug up un old base to give it a try. It worked flawless, I couldn't believe it. I told my machinist buddy and he said "no way". I invited him over to show him. He couldn't believe it worked. He asked to borrow it and a week later he brought me it back with a spare! He made one for himself too. I went to the local bearing suppler and ordered a 100 3/8" od by 5/16" id brass bushings. I must have done about 50 bases since then and never had a problem. I'm still using the original bit and haven't had to use the spare yet!


Tue Sep 20, 2016 1:13 pm
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