thats interesting have you used this method? I just read the instructions on his site. It says you put the pilot into the center throttle bore of the carb. I dont get how the pilot works because the throttle bore is 5/16 the drill bit is 11/32 or 3/8. so even if the pilot fits in the bore how does it help the drill bit get started? since the 3/8 drill bit cannot fit into the hole to reach the pilot? what am i missing here?
Gary, just click the "enlarge image" link and take a close look at the drill bit!!! http://www.gesslerheadporting.com/gesslerheadporting/ghp.nsf/GHP-Q4301!OpenPage Devon
oh i see, it has a half inch of 3/8 cutting threads at the top. Ok that makes sense. Nice bit I wish I could buy just the bit. Its ideal. So ya its a big step drill. 1 huge step 5/16 to 3/8. Nice.
Is that a custom made bit just for qjets or is that bit used for something else in machining or industry somewhre? Plus it has that nice pilot to protect the inner holes and guide it in. ya thats a nice kit.
i got the kit from Gessler last year at the BPG nats and have used it several times. its worth the $$.
"Is that a custom made bit just for qjets or is that bit used for something else in machining or industry somewhere?" It is a custom made bit to bore a 5/16" hole out to 3/8" exactly on center. The bits are custom ground, not machined, and hand sharpened. Each one is used to bore a Quadrajet throttle body for bushings before they leave here. We are the source for these bits, at least most of them. Several others have copied them, or attempted to in recent years......Cliff
Ok, well I Did it Myself too. lol I figured out a way to do it for minimum expense and maximum satisfaction. I did it my own way and hey I saved $40!! First of all, it turned out perfect. The shaft is aligned, no binding , no leaks, no play whatsoever. The blades fit perfect in the bores. No more vacuum leaks. Im pulling 22" at 500 rpms. Nice smooth idle. Heres how I did it. Parts and Tools from McMaster Car 2 3/8 OD, 5/16 ID bronze sleeve bushings by 3/8 long .60 each $1.20 1 step drill bit $17.56 http://www.mcmaster.com/#8841a22/=59zp2o this bit has steps that are 3/8 long Tap handle - I already have one so i didnt need to buy it. Air Die grinder with small cutoff wheel. 2" - already had this too. You could use a narrow file. Loctite - had some in a drawer 1. flip the carb over and remove the two phllips screws that hold the bowl onto the base. 2. flip it right side up and remove teh other two screws holding the bowl to the base. 3. using a file or a grinder. CAREFULLY and with extreme control and minimum speed, grind the threads NOT HEADS, threads that are sticking through the shaft. Grind them flush, be careful not to nick the throttle bores or anything else besides those threads. 4. Once those are fllush, remove them with a flat blade screwdriver. if you feel ANY resistance whatsoever STOP and look and make sure you ground it flush with the round shaft. The screws should come out effortlessly. If you feel resistance stop and find out why. Those screws are staked and very ver thin. They WILL BREAK OFF with the least little bit of torque, even if you think they wont, THEY WILL. Remove the blades. 5. Discononecet the secondary linkage rod. I slightly unbent the rod at the small end. If you do this, do it very slightly because it can easily tear. Maybe there is another way but this is how i did mine. 6. Get out the step drill bit and put the 5/16 step into the 5/16 throttle shaft hole. If it fits snug procede. If not, wrap it with teflon tape until it fits snug. Make sure to wrap it clockwise looking at it from the front. 7. use the tap handle, Aluminum is very soft and the bit cuts very very easily by hand you dont need a drill. Be sure to push the drill bit all the way in at all times, keep it flush against the hole at all times. The 5/16 step is following the existing hole so as long as you keep it tight against the existing hole it will turn out straight. Turn the tap handle clockwise until the 3/8 step is all the way in. Take the bit out of the hole and test fit the 3/8 long 3/8 OD bushing. It should sit almost flush. Do a couple more turns with the drill bit until is sits flush. Do the other side same way. 8. Blow it out with compressed air. Clean the holes. Put loctite on the bushings and install. 9. Put the shaft back in the base. reinstall the linkages. Put locktite in the screw holes and install the blades. Do not tighten them down leave them loose. Align the blades so there is no light getting past them. Carefully tighten the screws. use a very small screw driver. Do not use much force at all or the heads WILL BREAK OFF! Just snug them up. McMaster car sells the screws. they are #3 48 thread. I think they are 6 bucks for 100 but I dont see why you need any. You can use the ones you have if you are careful. If you are not careful and you break a head off. you are totally screwed! 10. Wipe off any stray loctite, blow out the passages one last time, put the carb back together and install. ### NOTE this is just how i did it, I am not an expert and many people on this board will Im sure scoff at the way i did this. I really think that they go way overboard with drill presses and jigs and special custom made 70 dollar bits and so forth. Those guys are machinists and are used to doing everything to within .0001 but I really tink its not that critical in this case. This repair was so easy and turned out perfect. The car runs so much better, more vaccum and steady vacuum. The mixture screws are much more sensitive now and there is ZERO play in my throttle now. nice. Follow my advice at your own risk! Your results may be different. But this way worked for me and I saved $40. That money adds up. and i dont have much to begin with. Dont be scared. No wait, yes, be scared be afraid be very afraid, and take it slow, you can do this without being a machinist or having a drill press or even a drill. Maybe I just got lucky, I dont know. But it worked for me.### Total cost was 18.20 + 5 bucks shipping. Cheers.
Glad things worked out for you. Even so, for anyone else reading this, read my previous response below at least one more time, BEFORE attempting to open up each end of your throttle bodies primary shaft bore with a "stepped drill bit". I've seen this attempted before with DISASTEROUS results!ou: Those bits do NOT have enough lead to keep the cutting surface on center. They do NOT cut on two or more sides at the same time. They are NOT tight in the worn throttle shaft bore. Those bits can and will walk all over the place. For this process to be 100 percent successful every single time, the cutter MUST have a lead, or section that extends thru the bores to keep the cutter on center. The lead MUST extend, at a minimum, to the center section of the carburetor or the cutter will "walk". Hope this helps some?.....Cliff
there was nothing to stake they are flush now, i did use loctite though, you dont think that will be enough to keep t hem from vibrating loose? If you think it will fail I will order some new screws, McMaster car has them by the 100, 6 bucks but maybe fastenal will have some individual ones, theres one in town here.
Fastenal will NOT have them. They can get them, but not slotted drive, button heads in a hardened material. All they can get at Phillips drive "soft" screws or stainless ones, minimum order is 100 screws. Ours are made for us, hardened steel (apprx grade 5), zinc black oxide, 3-48 X 1/4" long, slotted drive, button heads. I would loc-tite and stake them, if you like your engine!?!.....Cliff
Cliff Im curious what is the importance of being hardened and is it hard to stake hardened screws? Also what about the head style. Button head vs Pan head, what kind of problems can happen from the wrong head style or stainless steel instead of hardened steel?
Mild steel or "soft" screws strip right out, especially if they have phillips drives in them. The head shape is important, as it must be wide enough not to pull thru the holes in the throttle plates. The screws we have made are not grade 8, which would be too hard, closer to grade 5, and they stake easily.....Cliff
just few reminders,If an engine without computerized idle speed control is idling too fast and refuses to come down to a normal idle speed despite your best efforts to back off the carburetor idle speed screw or air bypass adjustment screw fuel injection, air is getting past the throttle somewhere. Common leak paths include the carburetor and throttle body gaskets, carburetor insulator spacers, intake manifold gaskets, and of course, any of the engine's vacuum fittings, hoses and accessories. It is even possible that leaky O-rings around the fuel injectors are allowing air to leak past the seals. Another overlooked item can be a worn throttle shaft. __________________________________________________________________ MR GASKET CARBURETOR BUSHING/PIVOT -- Designed to replace worn out or sloppy factory bushing; Gives smooth, trouble-free throttle operation; Fits 0.25 in. diameter throttle rod bushing.
Since this topic found it's way back to the top, we'll add some additional comments. One of those Hot Rod TV shows did a segment on how to rebuild a Quadrajet carburetor. I was asked to sponser the show, but declined since I was NOT allowed to have any input as to the content, even though I was assured that the "experts" they employed had over 40 years of combined experience and knew how to completely and correctly rebuild a Quadrajet carburetor. When the show aired, it was pretty good for the most part, with one BIG error showing up. Yep, you guessed it, installing shaft bushings. They showed drilling out the baseplate with a standard 3/8" drill bit and tapping bushings in with a small hammer. I'm not sure if this "stepped drill bit" information, or the TV show, or both were the main contributors, but shortly after than show aired we started selling quite a few bushings and screws without any custom machined self guiding drill bits. I don't want to "beat a dead" horse here. I will simply say to everyone, do NOT, under any circumstances attack your throttle body with a stepped or standard 3/8" drill bit in an attempted to put a perfectly sized hole exactly on center and fill it with a bronze bushing. I've probably made more money since this thread was started/Qjet TV show aired repairing throttle bodies than I have selling bushing kits for them. Sometimes it amazes me the amount of effort some folks will go thru and the risks they will take to save a few dollars. This is a job that needs to be done correctly and with exact precision, just like just about everything else associated with this hobby, IF you desire and expect good results with your project?.......Cliff
Does this mean something other than they asked you if you wanted to buy advertising on the show and you said 'no thanks'? I must have got lucky then because I just used a stepped drill bit and hand held it, i think hardware store bushings, im not sure now maybe i put it in the post above. Anyway, mine works perfectly, my leak is fixed, no play in the shaft/bushings anymore, no binding and 23 inches of vacuum with a dead smooth idle at 500 in drive. I bought a float and needle and seat from cliff, and his service is excellent and fast. I also bought a gasket kit and he made sure I got the right one. I did snap off one of the throttle blade screws which definitely was a setback but I managed to save the shaft. Another issue I had was a flooding issue which turned out to be the use of a cheap filter that can fit in either way. The good filters only fit one way. When I put the bad filter in i just put it in the way it fit which was the first way i tried so i thought that was right. I never really looked at it before, just put them in the only way they fit. So anyway, as a result of that the filter got in backwards and was letting dirty gas get into the carb which was keeping my needle from seating and I had a flooding issue. I noticed it only happened when I was almost out of gas not when the tank was full. So before I figured that out i was trying any conceivable solution so i ordered new seats and needles from Cliff hoping it was it, but it didnt fix it. It happened again. Finally figured out it was the filter in backwards so i replaced the filter and put it in the right way and havent had any more trouble with it.
"Does this mean something other than they asked you if you wanted to buy advertising on the show and you said 'no thanks'?" That's pretty much it. They wanted money only, and no input whatsoever as to the content of the final production. Good move on my part, especially when they showed drilling the primary side of the carburetor with a standard drill bit, then tapping in bushings. Amazing the things you can do with a little editing for a TV show. I wished everything in life was really that easy. I'm glad the "stepped" drill bit deal worked out well for you. Even so, I would highly recomend that others not attempt this. A stepped bit is NOT self guiding, only cuts on one side at a time, and any movement off center makes the hole to large to support the bushing effectively.....Cliff
so they didnt even use a stepped bit. They used a regular drill bit and clamped it in a vice? What part did they edit out?
I don't remember exactly what was shown, just a very quick "blip" of one of the actors turning about with a hand drill loaded with a standard bit, then a quick clip of tapping the bushing into the hole with a hammer (nearly as I can remember). What is important for the readers to know here, is that any attempt to open up either end of your throttle body to accept a bushings should have two goals. 1. Staying on center. This is accomplished using a cutter with a long lead to pull/guide the cutter on center. It is NOT possible to stay on center with a standard drill bit, or a stepped drill bit. They do NOT have a "lead", and can/will follow their own path as they cut into the throttle body. Keep in mind that the hole you are boring into can be considerably worn, ie out of round or worn more one direction than the other. Unguided, it is NOT possible for those types of cutters to stay on center and/or follow the original bore with any sort of accuracy. 2. Sizing the hole. The new bushing should have a very slight interference fit with the new bore. It will stay put and use it's inner bore as the new wear surface. Since we use oil impregnated bronze bushings (not thin brass sleeves), they are a permanent repair. Attacking the bore with a drill bit that is unguided and only cuts on two (fluted bit) or one (stepped bit) will make a hole that is larger than the actual diameter of the bit. This happens once again because both parts (the bit and the throttle body) can NOT be kept in perfect alignment during the drilling operation. Even if you were using a drill press, and had the throttle body mounted/clamped below it, the bit will "chatter" and walk off center as it doesn't contact the cutting surface evening and (once again) doesn't have a "lead" to stabalize it/keep in on center during the boring operation. I've had more throttle bodies sent here since the TV show ran (and this thread came out) than in all they years we have been in business combined for repair. (This alone should serve as a WARNING for the hobbyist trying to save $20 or so to get two little bronze bushings correctly installed into his hasn't been made for 30 or 40 years difficult to replace factory Buick throttle body). The course of action we use to save the throttle body varies depending on how bad the well meaning hobbyist has hosed it up? I have several methods to repair them, the easiest being to bore deeper into the material with the correct cutter, and install a longer bushing. I'll coat the out portion of the longer bushing with Marine Tex to give it additional support where the hole was overbored/off center. For the really messed up ones, I can cut a larger diameter bushing on our lathe and use a larger self guiding bit. The good news is here I've been able to save all but a very few of them. It's a good thing I've got several hundred good used ones in the core pile!.......Cliff
