Fitting Extended Throttle Shafts on Holley 94's

Hey folks,

I just bought a pair of Speedway Motors extended throttle shafts for a pair of 94's I am rebuilding. See link below:

http://www.speedwaymotors.com/Ford-Holley-94-Extended-Throttle-Shaft,7124.html

Anyway, I ran the prescribed 9/32" drill bit through my carb bases, carefully set up on my old Craftsman drill press, and then went to slide in the shiny-new Speedway shaft, but low and behold, it wouldn't go into the base. So I look at the trusty drill bit size chart and it says that a 9/32" bit is equivalent to 0.2812", which is smaller than the .282" shaft I just purchased. If anything, using a 9/32" bit would yield a light interference fit...not what you want for a carburetor. Anyway, I'm not exactly trying to re-invent the wheel here; I am sure countless HAMB'ers have installed these very shafts, so what am I doing wrong?

Thanks for the help,
Casey

 

Have you miked the drill bit and the shaft? Maybe the shaft is too big or the bit is undersize. You could ream the carb body to fit the shaft if you have an adjustable reamer.

 

Measure then decide. the hardware store drill bit isn't all that precise, usually.
Micrometers are cheap.

 

I just installed 3 shafts - using specified bit - with no issues - fit was good - a little loose if amything. Drill bit tolerance ?

 

Try putting the shafts in the freezer. Could shrink them to the dia you need, but might not give enough play to move freely.

 

I had a snug fit and no reamer small enough to fit. I sanded the shafts with 1000 grit by hand and then polished on my buffer. Worked perfectly.

 

A cleaver trick is to coat the shaft with rubbing compound and lock it in your drill chuck. Now slide your throttle body onto it and turn you drill on slow for about 30 seconds. You will be amazed at how much smoother your shaft will fit. Oh, don't forget you rinse all the compound out before assembly.

 

I've used these shafts. I bought a "chucking" reamer from tool supply store .005" larger than shaft dia. Got a real nice fit after reaming.
The chucking reamer is smooth sided for chucking up in drill or collet. Take your time in lining up the base.

 

I'm wondering why you need extended shafts??
Duane.

 

for dual or triple linkage assemblies