No drill Qjet throttle bushings.

[Clone TIE Pilot]

Found this on the internet, DIY Teflon bushings for Qjets which doesn't require drilling. Here is the link: http://rmcavoy.freeshell.org/Q_Jet_bushings.html

There is also a forum thread about this too: http://www.chevytalk.org/fusionbb/showtopic.php?tid/271238/

 

[jetsetw31]

Now that's a good fix. I love good ideas.
I'll be doing that from now on.
Thanks Clone TIE Pilot
T

 

[Clone TIE Pilot]

One of the advantages of not having to drill is the zero risk of cracking the base plate. The passenger side throttle sfaft boss is very thin and prone to cracking if drilled slightly off centered. Another advantage is better vacuum sealing as metal bushing will still leak quite a bit of vacuum.

 

[Bonnewagon]

What a great fix! Many thanks, I can't wait to try that. I wonder if Ignition Man Dave is the same guy that used to post on Classical Pontiac years ago? EDIT: Yup, that's him, attitude and all. After reading his posts on that forum I'm sure of it.

 

[Longroof79]

That is a good fix. I'll have to keep that in mind when considering rebuilding a Q-jet to put on my engine. I know that is a common problem on Q-jet's. I could see where the teflon would in fact seal better around the throttle shafts than the brass or bronze bushings.

 

[88hurstolds]

I purchased PTFE sheeting (Teflon) to do this over a year ago and haven't gotten to it.
I would suspect that this would be a Band-Aid fix and not something that would last for more than 30k miles based on heat cycling and rotational wear however PTFE is very chemical resistant so it has that going for it...

 

[gp02a0083]

the PTFE you are talking about will hold up well under the chemical environment they are subjected to, in addition the heat cycling shouldn't bother it too much. I use PTFE sheets in my environmental chambers at my job. They last no problem at 170C = 338F

 

[Clone TIE Pilot]

Some Holley carburetors and throttle bodies for EFI use teflon bushings. The guy who came up with this repair, Ignitionman, used to work for Holley and claims that metal bushings require alot of clearance to prevent binding which also allows alot of air to leak through.

 

[G-Body_Vet]

I'm actually surprised someone didn't come up with the idea of PTFE bushings sooner. I deal with PTFE bushings and seals quite a bit and they're subjected to environments a carb will never see (high pressure steam/various chemicals in refineries, steel mills, power plants ,etc). We use them in rotary valves as well as sliding stem valves where they seal the valve body from the shaft. The only time I ever see problems with leaks is when they've been improperly installed on galled shafts or in pitted bores.

 

[Clone TIE Pilot]

Well I just did this and found out that E4ME baseplate are a little different from the older non CCC carb in the link. The driver's side throttle shaft bore has a very shallow step down area, too shallow for a bushing to fit. So you still have to drill but not nearly so much. Get a 11/32 bit and drill about 3/8 into the bore, then there will be room for a teflon bushing. The good news is that the passenger side shaft bore has a deep step down area and doesn't require any drilling. This is good because the passenger side shaft bore is in a very thin boss that cracks easy if drilled.

I also discovered one other repair tip, if you strip out the lean stop screw for the mixture solenoid. You can fix it quickly by making a aluminum foil cylinder and dropping it into the threaded hole for the lean stop screw. The foil will act like a mini helicoil and allow the lean stop screw to thread again. There used to be a proper repair kit that replaced the lean stop screw with a special stud and nut but they seem not to make it anymore.