throttle body ques.
Thread Starter
Intermediate
Joined: Feb 2006
Posts: 34
Likes: 0
From: Pemberton N.J.
throttle body ques.
Hi all and thanks soooo much for your past help (corvette newbee here but ase mastertech) I was cleaning my throttle body on 86 TPI yesterday and noticed some throttle shaft loosness (aprox .030) seemed like a lot and have been having some off idle stiffness and have to tap throttle to get back to idle.new TPS and trans TV cable and throttle cable.Cleaning and WD40 only works a day or 2. I was wondering if there is a kit like a reamer and bushings for throttle shaft bores or am I dreaming.Also how effective are these freeflowing throttle bodies they sell on a stock L-98. Seems like putting more air in is usless if you have done no modifications to add more fuel and get it out (exhaust system) too. Again Thanks for your expertease.
Chuck Dublick Countywide transmissions.
Chuck Dublick Countywide transmissions.
Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
Its not so much the TB with air as the plenum and runners, and stock injectors will handle a good start, but the exhaust manifolds and exhaust pipe doesn't allow flow...
Headers and good exhaust system, differ plenum & runners (HSR/SR) or modify the plenum and runners for more flow...
Headers and good exhaust system, differ plenum & runners (HSR/SR) or modify the plenum and runners for more flow...
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Yep, just like with an old, worn carburetor, this will cause you problems. There are folks that can redo and upgrade your stocker. And in the process, the good ones will solve this problem with precision bearings or bushings. Or you can just upgrade to a quality aftermarket TB. If the early ones are like the LTx TBs, it can be punched out to 52mm. Some even take them to 54mm. And you're absolutely correct, a larger bore is not needed without significant engine modifications. I only use a 52mm on my engine now and I've tried them all, up to 58mm. And welcome to the forum from a fellow ASE master tech, diesel, gas, medium and HD trucks in my case. 
Last edited by Corvette Kid; Jan 19, 2007 at 07:49 PM.
Burning Brakes
Joined: Dec 2006
Posts: 1,090
Likes: 80
From: Burleson Texas
Yep, you need new bushings and perhaps a new shaft. There is a guy on ebay I used to bore my stock throttle body out to 52mm. This included new shaft, brass bushings, & port matching the air foil to the new bore. He charged $150 plus about $12 shipping. I ran it on my auto cross car this season - no problems! 
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Yes you need to have it rebuilt or replaced.
I'm guessing the slop is front to back on the throttle lever side?
Next time the idle hangs, pop the hood and see if the throttle is against the idle set screw. If it is, jiggle the throttle shaft up/down and in/out and see if this affects the idle.
I'm guessing the slop is front to back on the throttle lever side?
Next time the idle hangs, pop the hood and see if the throttle is against the idle set screw. If it is, jiggle the throttle shaft up/down and in/out and see if this affects the idle.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
I doubt it, I sent mine off. The TB is a pain in the butt to work with and the slightest misadjustment one way or the other will cause it to bind up. They aren't intended to be serviced, the throttle lever is sort of riveted in place and the throttle blade screws are soldered in.
Also there are no bushings. It wears directly on the aluminum housing. Bearings can be installed but will require some machining.
Also there are no bushings. It wears directly on the aluminum housing. Bearings can be installed but will require some machining.
Last edited by CentralCoaster; Mar 30, 2007 at 11:20 PM.
Team Owner
Joined: Jan 2003
Posts: 20,304
Likes: 240
From: Summerland B.C. Canada
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