Rochester B throttle shaft bushing repair!

Looking thru the forum i never came across a detailed how to or anything really covering whats involved in repairing a leaking throttle bushing. Thought i would post up my rebuild i did today of both my single barrel carbs for others to see what it is all about.

I got the bushing kit from Quadrajetparts.com and it took a week to get to my door.

The old worn out throttle shaft hole. My front carb was so bad fuel would just squirt out after accelerating. It found its way down the intake and caught fire one day from the exhaust manifold.



The kit has 6 new bushings, drill bit, drill bit stop, new butterfly screws, red thread lock and the bushing installation tool.



First thing to do is setup the drill bit and stopper to the correct depth to allow the bushing to be seated flush with the carb face.



Clamp the body into a vice and use a drill press to drill it out. It honestly took no more than 10 minutes to dill out the four holes for the two bodies.

Note: drill out both holes in each body prior to installing any bushings. If you were to install one bushing and then drill the other side the drill bit can slightly work away at the new bushing located on the opposite side you just installed.

You can see here the hole does not go right thru but stops about .55" down.



Apply some of the permanent thread locker and use the bushing tool to tap in the bushing.



After it was all finished you will see and feel such a difference. The shafts are not snug but have just the slightest resistance on them. Not to a point to worry about sticking open but tight enough you know fuel will not piss out. I found out that one of my throttle shafts was also slightly oval after installing the bushing and was lucky enough to have a spare carb to steal a perfect new shaft from.



Hope this post will help other understand whats involved and make it easier to accomplish.

Scotty

 

One more entry for tech week!

 

Great post! There have been several people wanting throttle shaft repair kits for the B series, me included. Thanks for sharing...

 

I've always been concerned with this process, the shaft wears the housing on one side only and is eventually oval. Then, when you start a drill in to open the hole up for the bushing, you follow the old hole which will be off center, offset to one side. The shaft will be tight but the butterfly will not be in the center of the throttle bore. Any experience on this or is the offset too minor to worry about?

 

I have done this repair many times on Quadrajets and never had a problem. The holes in the throttle plates are usually large enough to allow a person to properly center them in the throttle bore.

 

You are absolutely right in that the drill will follow the path of least resistance which will be 1/2 the ovality. If the bore were worn .010" all to one side the drill would cut .005" out of true position which as stated is likely less than throttle plate screw clearance. If true position is required an endmill can be used instead to correct it.

Scotty,

Nice work, pictures, and writeup.

 

Love to grind my drill bit like that one shown, anybody give me the basics???

 

for doing Q-jets we had a piloted drill bit and never had any problems. can't recall the caliber of ammo casing we used for bushings.

 

Just a casual comment/question
I have old Holley 4 bbl carbs that never had bushing and are made of aluminum.
No bushing are available afaik. I wonder if a kit like yours might be made to work?
I know I'd need to know sizes, etc.
Just thinking out loud.
Appreciate the post, thanks
Jim

 

I have used the K Line valve guide liner kits for the rochester and holley carbs.

 

Are you guys paying $80 for this repair kit? I just picked up a rochester b to replace my carter yf on my '51 but for the price of the throttle shaft kit, the rebuild kit and a new float I could almost buy a reman carb and use mine as a core. Is there ANY allowable play in the throttle shaft? I can't see mine move up and down but I can feel it.

 

I know this is an old post but i thought it may be of help to others.

You are correct that a regular drill bit will follow an out of round hole, that's why the kit highlighted in this post contains a special piloted drill allowing it to be located and centered with the pilot in both the inside and outside of throttle bore. The cutting surface on the special drill is more like an end mill with a flat cutting edge and not tapered like a normal drill bit.

Anytime the throttle plate/s are removed, they need to be re-centered in their bore/s. If you plan on doing this mod without a milling machining, I recommend that you do drill and install the throttle arm side bushing(most worn) before drilling the second hole in order to give the pilot a stable bore to locate the drill.