holley 3810 throttle shaft bushings

[Timothy B.]

Thought I would post a picture of the bushings I installed in my 3810 base plate. I used valve guide bushings and the diameter is .371-375. The drill had a pilot and reamed the hole to .405 then tap the bushings in for a nice fit. The shaft is very nice fitting, not tight but just right.

I had to install a new secondary shaft because it was wore but suprisingly the primary shaft is very good. I think from a previous rebuild someone may have damaged the secondary shaft and installed a used shaft. I drilled completely through the sides and installed the bushings through the entire length.

Also shown is my sanding table and 220 wet paper. This did a fantastic job showing the low spots on both sides of the base plate and was easy to do with the throttle shafts removed. Finally, I taped the two unused screw holes and will install screws from a doner in hopes of a good gasket seal. I don't think it's necessary but I did it anyway.

[Joe R.]

Re: holley 3810 throttle shaft bushings

Well, I'm impressed! Are you a machinist by trade or tool and die maker? You should consider performing this service for other poor old carbs out there needing assistance. The permanant cure for idle-itis.

Thanks for the pics also! Impressive work!

JR

[Stuart F.]

Re: holley 3810 throttle shaft bushings

Tim;

Nice job. You're my kinda guy, meticulous to a fault (does that sound right?). Next, if you haven't done it already, you could lap in the butterflies. I used to do this with great results - no hesitation, very positive action. Just use a little oil and emory cloth, hold the base up to a bright light and look for high spots (where the light does not come through. Work on the high spots until you can't see any light coming through at all. Then, you can even increase the shaft return spring pressure, if possible, for even greater positive seal. It's kinda like the next extension of blueprinting a carb, but then I'm sure I'm not telling you anything you don't already know.

Stu Fox

[Dale S.]

Re: holley 3810 throttle shaft bushings

Very nice, Dale

[Gerard F.]

Re: holley 3810 throttle shaft bushings

Great job, Tim

Now I have the encouragement to do my 3810 base plate.

Are those new throttle plate screws or were you able to reuse the old.

[Clem Z.]

Re: holley 3810 throttle shaft bushings

make sure those extra screws do not set over a open part of the manifold plenum as they can end up in the engine if they come loose. i would use loctite on them to be sure if you do use them. i think that is why GM left them out. JMHO

[John D.]

Re: holley 3810 throttle shaft bushings

timothy,

Is there a kit that you used ?. Can you provide the info ?

thanks

[Clem Z.]

Re: holley 3810 throttle shaft bushings

timothy,

Is there a kit that you used ?. Can you provide the info ?

thanks

here you go. http://goodies-speedshop.com/i-30091...tructions.html

[Timothy B.]

Re: holley 3810 throttle shaft bushings

I did not use any kit, just went to local machine shop and they lent me the drill with pilot and gave me a few split valve guide bushings. This drill is made to be used to install these bushings and there is a approx. 1" long pilot, 3/8" diameter on the end to keep it straight as it drills.

The drilling took two minutes but I took some time to set it up. If you go into one side and then into the other just a little off, the shaft will bind. It's really not hard to do, get a long 3/8" bolt w/ collar and cut the head off to use as set up tool. The drill I used cut a hole .405 diameter and the bushing slid in with interference. The holley shaft fit nice without reaming but there are reamers to enlarge the diameter as this is done with valve guides.

The picture is the bushing and I cut it to size with a hand held copper pipe cutter. Just slide the bushing over a 3/8" bolt collar and cut slow just like a copper pipe. I did not loctite the bushing because of the fit and I think it would have pushed it out anyway but the next one I probably will loctite just for my own benefit.

As with anything, the more you do the better the technique, I was able to remove the old throttle plate screws and reuse. I am aware of the problem removing them which is the most difficult part of the job, in my reading some people suggest tightening them to brake them off then grab the end and unscrew out because of the hassle of drill and tap such a small screw out of the shaft. Sorry for the long post, I wanted to share this with others on the board.

[Stuart F.]

Re: holley 3810 throttle shaft bushings

Tim;

Thanks for your additional information. It was prettty clear to me from your first post what you did, but others assumed what they they thought you meant, I guess.

On the screws, depending on what carb brand you work with, the safest way to take the throttle plate screws out that I have found is to use your Dremmel tool to grind away the swagged (staked) end some first as that is what binds the screw when you try to unscrew it. Most are usually just brass screws and they break easily with any resistance. I realize one can damage the shaft if they are not careful, but it is worth a few grind marks to save the screws and shaft. Upon replacing, a little Loctite works fine. I have seen it where others have used Epoxy, but it don't look cool and some is eaten away by the gas - specially if the shaft and screw were not perfectly clean and a good bond was not obtained.

Stu Fox

[Joe C.]

Re: holley 3810 throttle shaft bushings

I did not use any kit, just went to local machine shop and they lent me the drill with pilot and gave me a few split valve guide bushings. This drill is made to be used to install these bushings and there is a approx. 1" long pilot, 3/8" diameter on the end to keep it straight as it drills.

The drilling took two minutes but I took some time to set it up. If you go into one side and then into the other just a little off, the shaft will bind. It's really not hard to do, get a long 3/8" bolt w/ collar and cut the head off to use as set up tool. The drill I used cut a hole .405 diameter and the bushing slid in with interference. The holley shaft fit nice without reaming but there are reamers to enlarge the diameter as this is done with valve guides.

The picture is the bushing and I cut it to size with a hand held copper pipe cutter. Just slide the bushing over a 3/8" bolt collar and cut slow just like a copper pipe. I did not loctite the bushing because of the fit and I think it would have pushed it out anyway but the next one I probably will loctite just for my own benefit.

As with anything, the more you do the better the technique, I was able to remove the old throttle plate screws and reuse. I am aware of the problem removing them which is the most difficult part of the job, in my reading some people suggest tightening them to brake them off then grab the end and unscrew out because of the hassle of drill and tap such a small screw out of the shaft. Sorry for the long post, I wanted to share this with others on the board.

Nice job, and great pictures, Tim!

It's always great to see the fruits of the labor of those folks who take pride in doing the job themselves.

After you put LocTite on the screws, you should file them even with the throttle shafts. If you want to partially blueprint the carb, you can go further by thinning the throttle shafts and recoloring them black.

[Gerard F.]

Re: holley 3810 throttle shaft bushings

Tim,

Your post here would make a great Restorer story. I was planning on doing one on the plating, coloring, and restoration of my 3810. When I got to the base plate, I ran it the problem with the bushings on reassembly, so I bought a replacement base plate.

So now that you have the bushing problem resolved, maybe we could do two companion stories, I stick to the upper part and you do the lower part.

[Clem Z.]

Re: holley 3810 throttle shaft bushings

to get a good alignment in the drill press install a 3/8" dia rod clear thru the holes in the base plate,then clamp the 3/8" rod in the drill press chuck as this will align the base plate holes with the center line of the drill press. now clamp the baseplate in the drill press vise and you then remove the 3/8" rod from the drill press chuck and the base plate with out disturbing the baseplate alignment in the vise.