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THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

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THE FRENCHTOWN FLYER
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THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #1 by THE FRENCHTOWN FLYER » Mon Sep 23, 2019 10:30 am

I have several used 2100 and 2150 carbs that I want to re-bush the throttle shafts. I called Mikes and Allstate and they will sell me bushings but not the piloted reamer, which they say they had specially made. I want to make a reamer with a pilot long enough to reach thru the carb body with the precise O.D. for the bushings on the reamer. So my questions are:

1. Does anybody make a commercially available reamer like that?
2. If no commercially available reamer is available does anybody have one with the long pilot like that? I'm trying to keep the shaft hole as close to perfect alignment with the original shaft C/L as possible.
3. What is the O.D. of the replacement bronze bushings?
Has anybody put seals on the ends of their shafts and if so what type? I am not using any choke linkage, trans K/D lever, etc. on the ends of the race carbs so the shaft ends are available / accessible.

Many thanks in advance.
FTF
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #2 by woodbutcher » Mon Sep 23, 2019 11:01 am

:D Hi FTF.Check in tech archives under misc for carb shaft bushings.Might be info that you can use.
Good luck.Have fun.Be safe.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #3 by JackFish » Mon Sep 23, 2019 7:21 pm

I don't know what you need but there are reamers and bushings available on ebay.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #4 by THE FRENCHTOWN FLYER » Mon Sep 23, 2019 8:31 pm

Thank you.
Let me clarify,
I want a reamer with a pilot. A pilot long enough to reach through the carb body from one bearing to the other, with a reamer on the end. The throttle shaft is .375" in diameter. Most commonly available Oilite bronze bushings with a 3/8 I.D are .500 O.D. so the reamer on the end should allow for me to bore and install a .500 O.D bushing.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #5 by mtbikerTi » Mon Sep 23, 2019 9:30 pm

Maybe something like this would work: Throttle shaft bushing repair kit.

I'm not sure how long that shaft is but you may be able to use it as a pilot with the drill on the other side of the carb, or you could use it as the beginnings of a custom reamer.

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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #6 by THE FRENCHTOWN FLYER » Mon Sep 23, 2019 11:25 pm

Thanks mtbikerTi. I will order a kit and check it out. I'm a little 'iffy' about the directions as they say to first run an undersized drill thru the body. What centers the undersized drill? Also, one pic shows a pile of replacement bushings. I would like to find out if I can order a pile like that, not just the 8 that come with the reamer. Many thanks.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #7 by MechRick » Mon Sep 23, 2019 11:55 pm

One of the reasons I bought my mini mill is for bushing carb shafts. Haven't done one yet, but it seems to be a perfect solution. Clamp carb to table, chuck a 3/8" pilot through the carb to line everything up, then lock everything down, lift mill head up, install reamer bit and make chips.

Something else I've thought about is finding reamers with shank diameter the same as the throttle shaft (3/8" in your case), slide it through the carb casting before chucking in a drill, pulling through the carb instead. Seems like it would work...

The one time I bushed a carb was with nylon bushings. Wasn't completely happy with the results, although it did work.
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http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #8 by THE FRENCHTOWN FLYER » Tue Sep 24, 2019 12:08 am

MechRick, I have a right angle mounting plate I use to flycut Holley throttle bodies on a mill. I was thinking of using it if I am not successful with the piloted drill / reamer thingie. Thanks.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #9 by Lazy JW » Tue Sep 24, 2019 8:34 am

Piloted reamers are routinely used used in the gunsmithing trade for chambering firearms. Any of the folks making chamber reamers could probably make one, but they would likely be prohibitively expensive.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #10 by THE FRENCHTOWN FLYER » Tue Sep 24, 2019 9:07 am

It seems like there is enough ambiguity about the correct way to do this fix that I will take pics and post my results.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #11 by MechRick » Tue Sep 24, 2019 11:20 am

That will result in a well-visited thread.

I once dug up a reference for using sectioned rifle brass to make custom thin wall brass bushings. 5/16" throttle shafts use .308" brass sized up a bit, .375" brass might work for 3/8", if you could find some.
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #12 by CNC-Dude » Tue Sep 24, 2019 4:30 pm

One issue with reaming badly egg-shaped holes even with a pilot is it will still play off some because the bore is too sloppy to hold the reamer straight. One fix is to gradually drill the bores oversize until all the out of round or eggshape is removed, then get a pilot to fit the oversized hole then the reamer will follow the bore more precisely.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #13 by THE FRENCHTOWN FLYER » Tue Sep 24, 2019 5:11 pm

Thanks CNC Dude. It may come to that.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #14 by Blairsville Ed » Thu Sep 26, 2019 8:33 am

I was a tool maker for 20 years and I ground a lot of step reamers.
The length of the pilot is the problem as most chucking reamers are not that long.
One solution would be a counterbore with a removable pilot. You could use drill blanks for the pilot.

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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #15 by THE FRENCHTOWN FLYER » Thu Sep 26, 2019 8:47 am

Thanks Ed. Yep, I've got a couple of piloted mills (for topping off valve guides, etc.) so I gave that some thought, but I don't have the proper size to do this job. I ordered the kit posted above. One other consideration I realized is that the material between the two throttle blades also holds the shaft. I do not want to lose that middle support so I will have to go in from both sides and stop before the reamer touches the center support material. I can picture in my mind what kind of piloted tool I want but don't see one anywhere.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #16 by Fordman75 » Sat Sep 28, 2019 1:29 am

Here's a reamer I found sold by a Canadian company.
https://www.throttleshaftrepair.com/pro ... oduct2.htm

It's a piloted reamer with built in stop. It's not real cheap but I'm thinking about picking one up over the winter. I want to give it a try and see how well it works. I've got around 50, 2100 & 4100 Autolite carbs. So I've got plenty of bushings to install. If it works, then it would be well worth the money. Especially for the # of carbs I've got to deal with.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #17 by THE FRENCHTOWN FLYER » Sat Sep 28, 2019 10:37 am

TED, Please let us know how it works. I don't have fifty carbs to do - only a couple of pairs - so I ordered the cheaper HENKYO kit. I'd like to get a large supply of bushings for future carbs but I could not find a way to do that, even though one of the pics in their ad shows a pile of them.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #18 by Max_Effort » Sat Sep 28, 2019 9:42 pm

K-Line made throttle bushing kits. I have a couple and though discontinued, the kits pop up on eBay.
They used guide liners and special reamers.
You put the shank of the reamer through both bores. (The shank the drill chuck grabs onto) Chucked it into the drill then pulled the reamer through. (Backwards toward the drill motor) The shaft served as the aligner.

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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #19 by THE FRENCHTOWN FLYER » Sat Sep 28, 2019 10:12 pm

Max, Do you think a regular K-Line valve guide insert could be made to work? I have the tools to do valve guide inserts. Not sure what to do about the bearing in between the two throttle plates - how an insert could be fitted there without interfering with the plates.

On a related note today I pulled the 1.21 carbs off the intake. And discovered a potential leakage problem. The two 2V Clifford adapters are not the same front-to-rear. There is more meat on one side to seal against the bottom of the carb. I suspect with the 1.02 carbs that were on there previously there was no potential leak since they were 1961 vintage carbs and the 1.21s were '78 vintage. The base of the later carbs overlapped the 2V adapters at the rear by the PCV port. The quarter inch thick gasket sealed against the carb body but the gasket was un-supported. Turning the adapters around removed the potential leak.

SO IF YOU HAVE A CLIFFORD DUAL QUAD INTAKE AND YOU ARE USING 2 x 2 CARBS CHECK TO SEE THAT YOUR ADAPTERS ARE PROPERLY ORIENTED. THERE'S ONLY ABOUT AN ADDITIONAL 1/4 INCH OF MEAT ON ONE SIDE BUT IT COULD MAKE A DIFFERENCE SEALING WISE.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #20 by THE FRENCHTOWN FLYER » Sat Sep 28, 2019 10:19 pm

THE FRENCHTOWN FLYER wrote:Max, Do you think a regular K-Line valve guide insert could be made to work? I have the tools to do valve guide inserts. Not sure what to do about the bearing in between the two throttle plates - how an insert could be fitted there without interfering with the plates.


Max,
I just had another thought vis-à-vis the center bearing area. Insert the reamer but don't ream out through the center. Insert the reamer from each side only enough to bore the outer bearing areas, leaving the center as is.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #21 by Max_Effort » Sat Sep 28, 2019 11:25 pm

THE FRENCHTOWN FLYER wrote:
THE FRENCHTOWN FLYER wrote:Max, Do you think a regular K-Line valve guide insert could be made to work? I have the tools to do valve guide inserts. Not sure what to do about the bearing in between the two throttle plates - how an insert could be fitted there without interfering with the plates.


Max,
I just had another thought vis-à-vis the center bearing area. Insert the reamer but don't ream out through the center. Insert the reamer from each side only enough to bore the outer bearing areas, leaving the center as is.

That's how it's done with 2 bbl carbs. I just wrote the basic method. The kits used guide liners and a ball bearing to broach to size.
When I'm at the shop, I'll see if I have instructions with a kit.

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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #22 by Max_Effort » Sat Sep 28, 2019 11:45 pm

I just searched for a NOS or used K-line kit online and find there are other brand kits on eBay and elsewhere for around $40.

https://www.ebay.com/sch/i.html?_nkw=th ... epair+kits

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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #23 by MushCreek » Sun Sep 29, 2019 7:09 am

I'm a retired tool maker, so I know a bit about this stuff. First, you don't 'ream' from .375 to .500 in one shot. I would try to find a piloted counterbore about .015-.020 under the finish size. Cut it first with that, then go through with a conventional reamer of the right size. As was said above, line it up carefully in a milling machine first. If the holes are extremely egg-shaped or worn off of location, it could be difficult to get the location back, as the piloted bit will follow what's there, rather than what used to be there. Bad holes need to be bored to get location back; hard to do given the length required. The upper side is easy, but the lower one is tough. If I were doing a lot of them, I'd make some kind of guide bushing (hardened) that fit in the throttle bore to guide the roughing bit. The finish reamer will follow a good hole if aligned properly.

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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #24 by THE FRENCHTOWN FLYER » Sun Sep 29, 2019 12:05 pm

One thing to keep in mind is the throttle plate holes for the screws that hold the plates to the shaft are slightly oversized. I have watched a Ford carburetor technician install the plates by first lightly screwing the plates down. Then, with light pressure on the throttle shaft lever to close it completely (curb idle adjustment screw backed off of the stop) he gently tapped the plates with a plastic hammer to align the plates in the bore before tightening the screws permanently. Production screws then get staked permanently. I will probably just use button head allen screws with permanent thread locker.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #25 by Max_Effort » Sun Sep 29, 2019 5:48 pm

I pulled out a K-Line auto-tuff kit.

First of all, the K-Line reams forward. It has a long pilot before the reamer flutes. I was confusing it with a different style I’ve used :oopsie:

The K-line uses a .030” wall guide liner so you are reaming a max of .060” in one pass. The tool that inserts the guide, also has a dimple in the end to drive the broach ball. It’s simple and it works.

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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #26 by Max_Effort » Sun Sep 29, 2019 5:54 pm

This style is pulled back through the throttle body (not mine, just an example)
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #27 by THE FRENCHTOWN FLYER » Sun Sep 29, 2019 6:13 pm

Thanks Max.
A couple of observations: It looks like the K-Line kit does not address the center bearing support. Maybe if the two ends are rebuilt the center wear is moot.
I would want to face off the end of the body casting to be sure the insert goes in straight.
I ordered the second kit you showed with the 11 mm OD bushings. I'd like to order a pail full of extra bushings but did not see a place to do that. Maybe the kit will have bushing re-stock info.
I plan to turn a piloted driver to smack those thin wall bushings in place without damage.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #28 by Max_Effort » Sun Sep 29, 2019 6:50 pm

THE FRENCHTOWN FLYER wrote:Thanks Max.
A couple of observations: It looks like the K-Line kit does not address the center bearing support. Maybe if the two ends are rebuilt the center wear is moot.
I would want to face off the end of the body casting to be sure the insert goes in straight.
I ordered the second kit you showed with the 11 mm OD bushings. I'd like to order a pail full of extra bushings but did not see a place to do that. Maybe the kit will have bushing re-stock info.
I plan to turn a piloted driver to smack those thin wall bushings in place without damage.


Often, just the throttle cable/return spring end was re-bushed....

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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #29 by bubba22349 » Sun Sep 29, 2019 6:54 pm

The way those throdle shaft bushings are made they look like they would also work in the center support too if needed. :thumbup: :nod:
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #30 by MechRick » Sun Sep 29, 2019 11:26 pm

THE FRENCHTOWN FLYER wrote:I have watched a Ford carburetor technician install the plates by first lightly screwing the plates down. Then, with light pressure on the throttle shaft lever to close it completely (curb idle adjustment screw backed off of the stop) he gently tapped the plates with a plastic hammer to align the plates in the bore before tightening the screws permanently.


I've bead-blasted carbs in the past. The first one in and out of the cabinet I tried leaving the butterflies and shaft in place.

Big mistake. The glass bead packs in the space between the shaft and housing, jamming everything up solid.

Getting the butterfly screws out in one piece is by far the most difficult part of a re-bush job (or a bead blast job). I can relate to massaging the butterflies so they close completely before snugging the screws.

The bronze bushings are much harder than the aluminum/zinc carbs are made from. Bushing the ends should suffice. Using a pull-through reamer would allow bushing the ends without cutting the center..
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #31 by THE FRENCHTOWN FLYER » Mon Sep 30, 2019 8:34 am

That's the plan. What I plan to do is grind off as much of the protruding staked screw threads with a Dremel grinder before I try to loosen them.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #32 by THE FRENCHTOWN FLYER » Thu Oct 10, 2019 7:21 pm

THE FRENCHTOWN FLYER wrote:It seems like there is enough ambiguity about the correct way to do this fix that I will take pics and post my results.


I got my re-bush kit in the mail. As with nearly every part or tool I purchase nowadays this one needed some amount of rework and finessing to perform as I expected. I am in the process of writing a description of the process. I will post it on the H.A.M.B. because it is easy to upload photos there directly. I will post the text and the HAMB link on here so you can see the photos if it interests you.

I re-bushed the two 2150 carbs. As far as I can tell the job was a success. The car they're going on - The Family Truckster - has been winterized and put away until Spring, so no way to evaluate my work until then. But I'm confident.
Stay tuned.
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #33 by THE FRENCHTOWN FLYER » Fri Oct 11, 2019 12:06 am

Well, its past my bedtime but here is the description in its entirety. For a look at the accompanying photos please go to

https://www.jalopyjournal.com/forum/thr ... r.1168283/

TECH - CARBURETOR THROTTLE SHAFT REPAIR
Recently I discovered that my roadster pickup drag car had worn throttle shaft bores. This caused the throttle plates to be loose and leak air into the fuel / air stream. That created an erratic idle that could not be cured by adjusting the idle mixture screws or the curb idle screw. A search on the internet failed to find any good description on how to properly fix the problem. So this article addresses the problem. The carburetors in question are the Autolite 2150 series two barrels. They are a good carburetor with many advantages over other more popular aftermarket brands. Additionally, they are abundant in many bore sizes and available relatively cheaply. The steps outlined in this series apply to other brands of carburetors also.

01
The kit I ordered is from HENKYO. It consists of a 7/16” reamer on a 3/8” shaft body. The kit also includes eight knurled bronze bushings. I found it online for about forty bucks.
02
It was my plan to use the reamer in reverse. That is, insert the 3/8” shaft body into the worn shaft hole to align the reamer and then, by turning the reamer backwards (counter-clockwise) I could ream out the shaft bore on center with the original shaft axis. Well that turned out to be not as easy as hoped for as the reamer would not cut when held backwards and turned in reverse. More on that later…
03
Placing the carbs on a bench upside down gives access to the throttle plate screws. On these carbs they are #6 screws with extra fine threads. Some brands of carbs peen the threads of these screws; some crimp them; others use trocho-centric (vibration-proof) screws. It may be necessary to grind down the protruding thread with a Dremel tool before removal.

04 07
ONE CAVEAT HERE: THE SCREWS HAVE VERY SHORT HEX HEADS. Be very careful not to strip them out! They were tightly secured in the shafts and required that I modify a 3/16” six-point socket by grinding it down to eliminate the slight lead-in chamfer on the socket. Leaving the chamfer in place did not provide enough hex head purchase to loosen the screws (I tried several brands) and the hex will round over before reaching breakaway torque.
05 06
Mark the location of each plate. Once the throttle plates are removed the throttle shaft is ready to be removed.
Almost.
It will be necessary on an Autolite / Motorcraft 2150 carb to disengage the part throttle air metering rod cam from the shaft before the shaft will come all the way out. 2100 Series carbs do not have this feature (often referred to by carb technicians as “crowd control”).
08
The O.D. of the bronze replacement bushing measures 0.433”.
09
The O.D. of the throttle shaft measures 0.372”.
14
The I.D. of the bushing measures 0.375”.
27
To make the reamer useful for reaming in reverse it is necessary to make a couple of modifications to it. The first and most ticklish mod is to grind needed 45 degree reliefs on the trailing edge (soon to be the leading edge) of the reamer flutes to make it functional to cut in reverse. The second mod is to wrap about four turns of plastic tape around the first half of the reamer flutes. Thankfully, this is a six-fluted reamer so a six point 7/16” socket can be used to drive the reamer in reverse while the tape prevents damage to the cutting flutes.
15
Now the reamer shaft can be turned around and inserted shaft end first and driven in reverse rotation (CCW) with a slow electric drill so the long shaft will act as a pilot.
17
A bushing driver did not come with the kit. Pity. I turned a piloted driver on a lathe so there was no chance of damaging or crushing the bushing during installation.
16
You are now ready to drive in the bushing. It has a short lead-in area with no splines to make alignment to the bore easy.

18 28
I use a bushing retaining compound and lightly coat the outer splines with it to secure the bushing in the bore permanently.
21 20 19
Ream the carb body only deep enough to press in the bushing completely. In the case of this 2150 carb that meant the pilot needed to protrude out past the carb body by the length of the bushing. Ream to required depth. Drive the bushing into the bore.
22
Test fit the bare throttle shaft to insure it turns freely with no binding.
25
Now comes the re-installation of the throttle plates. Gently stone the edges of the throttle plates on a fine honing stone to remove any factory blemishes. (One of my original plates had a minor burr that had dug into the venturii bore in one spot – hence the need to stone them.)
23
Apply thread locker to the threads of the throttle plate attaching screws. LIGHTLY assemble the plates in the bores exactly as they were removed, but do not tighten the screws yet.
26
Back off the curb idle adjustment screws completely before the next step.
24
Using the plastic handle of a screwdriver gently tap the throttle plates while at the same time applying light pressure to the throttle lever to close the plates and perfectly center them up in the venturii bores. The holes in the throttle plates are intentionally oversized to allow for this perfect alignment adjustment before tightening the screws. Make sure everything is squeeky clean and re-assemble.

After assembly turn curb idle adjustment screws in until they just make contact with the throttle lever. For this multiple carb setup I turned each curb idle adjustment screw an additional one-half turn as a starting point.

303 motor 38
There you have it. Two like new throttle bores that are sure to make these vintage carbs perform like new.
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

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68Flareside240
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #34 by 68Flareside240 » Fri Oct 11, 2019 1:52 pm

Great work!

mtbikerTi
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Posts: 18
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Location: East Tennessee

Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #35 by mtbikerTi » Sun Oct 13, 2019 1:49 pm

Very nice! I found the bushings for sale without the reamer here: bushings

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THE FRENCHTOWN FLYER
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Re: THROTTLE SHAFT REBUSH - REBUILD, 2100 / 2150

Post #36 by THE FRENCHTOWN FLYER » Sun Oct 13, 2019 10:08 pm

Thanks mtbikerTi. I ordered more.
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

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