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350 tbi has play in the throttle shaft

mrgoodwrench

mrgoodwrench

1/2 ton status
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My 1990 suburban 350 tbi has has a pretty stiff gas pedal ever since i got it. When i first got it the truck was an auto (700r4) and the TV cable was stiff to pull so i always blamed that for the stiff gas pedal. The throttle cable was in poor shape so i replaced it but no change. And ive always just lived with it. I have since manual trans swapped (no more TV cable to blame) and it was still stiff. Lately ive notice that sometimes its even seems to have some rev hang when letting off the pedal. So i figure it was time to get to the bottom of it. After some inspection i have play in the throttle shaft and i think thats causing my issues. Long story short does anyone know what size bushings id need to fix my issue or know where to buy the proper boring tool and bushings? Thanks mike
 
I had my TBI rebuilt by a guy name Vic Morse. He did a complete modification job on my TBI, which included rebushing the TBI throttle shaft. Vic is no longer with us. He passed away about a year ago. The only company left that can do the same job as Vic did is CFM technologies.

My TBI. Bored out 1/8 inch/adjustable fuel press regulator/matched injectors/shaved intake face/rebushed throttle shaft
full
 
These guys sell a kit for the gm tbi as well as quadrajets.

quadrajetparts.com

Carburetor Bushing Installation Kit - 3/8" throttle shafts, Quad

Complete DIY carburetor bushing installation kit allows you to install bushings on all carburetors with 3/8" throttle shafts. Works on Rochester Quadrajet secondary throttle shafts. Kit contai...
quadrajetparts.com
 
ktmoutfront said:
These guys sell a kit for the gm tbi as well as quadrajets.

quadrajetparts.com

Carburetor Bushing Installation Kit - 3/8" throttle shafts, Quad

Complete DIY carburetor bushing installation kit allows you to install bushings on all carburetors with 3/8" throttle shafts. Works on Rochester Quadrajet secondary throttle shafts. Kit contai...
quadrajetparts.com
Click to expand...
So that's what I was trying to confirm the same kit that works on a quadrajet will work on a tbi correct? It doesnt list tbi in the description.
 
mrgoodwrench said:
Nevermind i read further and it does list tbi thanks very much.
Click to expand...
From that link.....

Rochester Q-Jet carburetors (Secondary throttle shaft)
Also works on the following carburetors (w/exception of throttle screws supplied)
Carter Thermo-Quad carburetors
Holley four barrel carburetors
Ford Autolite carburetors
GM TBI's
All carburetors with 3/8" throttle shafts.
 
ktmoutfront said:
From that link.....

Rochester Q-Jet carburetors (Secondary throttle shaft)
Also works on the following carburetors (w/exception of throttle screws supplied)
Carter Thermo-Quad carburetors
Holley four barrel carburetors
Ford Autolite carburetors
GM TBI's
All carburetors with 3/8" throttle shafts.
Click to expand...
Yep looks like a winner thanks again. Mike
 
Quadrajetparts.com is closed due to unforseen circumstances when i went to order. but at least now i know what im looking for and can do some searching.
 
mrgoodwrench said:
Quadrajetparts.com is closed due to unforseen circumstances when i went to order. but at least now i know what im looking for and can do some searching.
Click to expand...
Wow. I haven't order anything from them in a year or so. I wonder if the old man became ill.
 
After that response, they are metric. I have drilled and tapped mine for 4-40 screws in the past. Be sure to peen them over after installing.
 
mrgoodwrench said:
My 1990 suburban 350 tbi has has a pretty stiff gas pedal ever since i got it. When i first got it the truck was an auto (700r4) and the TV cable was stiff to pull so i always blamed that for the stiff gas pedal. The throttle cable was in poor shape so i replaced it but no change. And ive always just lived with it. I have since manual trans swapped (no more TV cable to blame) and it was still stiff. Lately ive notice that sometimes its even seems to have some rev hang when letting off the pedal. So i figure it was time to get to the bottom of it. After some inspection i have play in the throttle shaft and i think thats causing my issues. Long story short does anyone know what size bushings id need to fix my issue or know where to buy the proper boring tool and bushings? Thanks mike
Click to expand...
yeah - I have had issues with sticky gas pedal since day one. 99 percent of the time its the throttle cable. Damn cheap POS throttle cable. IF you can find one from GM, they are no better than what you get from amazon and AutoZone. they work for a couple weeks, and then they start sticking... flip them around so the cable can eat through the other side of the housing.... repeat. repeat. Especially aggravating when the throttle shaft is worn, but all of the actual resistance and extra effort has always been because of the cables.

I have had problems with the worn throttle shaft combined with the cable resistance causing the butterfly's not to return to the fully closed position. irritating as all hell when driving a manual and constantly kicking the pedal trying to get it to release.

I also am looking for a kit, or for a company that will rebush several throttle bodys for me.
 
1-ton said:
I had my TBI rebuilt by a guy name Vic Morse. He did a complete modification job on my TBI, which included rebushing the TBI throttle shaft. Vic is no longer with us. He passed away about a year ago. The only company left that can do the same job as Vic did is CFM technologies.

My TBI. Bored out 1/8 inch/adjustable fuel press regulator/matched injectors/shaved intake face/rebushed throttle shaft
full
Click to expand...
once upon a time I went over and talked to Vic... told him I was not interested in the other guys milling down the entirety of the air horns... and asked if he would be willing to leave it intact in a few spots... after telling him that this was a 4x4 that would see use, and describing the air cleaner I was building... he said he could do it, and it was a good idea... said he might offer more of them like that...

So, I always felt I was the first... but now that I'm older and wiser, I suppose its possible he told that to ALL the girls? :pimp:
TBI 1.JPG
 
Last edited:
scouthead said:
once upon a time I went over and talked to Vic... told him I was not interested in the other guys milling down the entirety of the air horns... and asked if he would be willing to leave it intact in a few spots... after telling him that this was a 4x4 that would see use, and describing the air cleaner I was building... he said he could do it, and it was a good idea... said he might offer more of them like that...

So, I always felt I was the first... but now that I'm older and wiser, I suppose its possible he told that to ALL the girls? :pimp:
View attachment 440879
Click to expand...
Lol
 
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