# Swap Engine or Crank?



## 70 GTO (Oct 21, 2012)

Hi Everyone, 

I recently did a M21 to TKX swap in my car, and once I was finished I took it to my mechanic to look it over because I had concerns with the pilot bearing. Long story short, the hole in the back of the crankshaft is too large even for the oversize bearing that's available through Butler. My mechanic called a machine shop and they said all that can be done is to replace the crankshaft. 

I figure that since they will be pulling the engine anyway, would it make more sense to just get another fully assembled engine? It currently has a 400 in it and I could take the opportunity to upgrade to a 455. Would my current 400 be valuable to someone with an automatic to put behind it? I'm wondering if the cost of a crankshaft swap would be about the same as a 455 minus whatever I would get for the 400.

I pulled the Muncie in June 2020 and I'm just ready to drive it again. It is taking a while for the mechanic to locate a crank in my area. I have known the mechanic/shop for over 10 years and trust them with my car. They are not a shade tree place at all.

Any thoughts or comments are appreciated.

Thanks, 
Alex


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## Jim K (Nov 17, 2020)

Go with what you want.. But finding a complete drop in 455 for a reasonable price (under 5 grand or so) will be tricky. Even on E-bay they start at 7K and go north from there. A forged crank is around 1K to buy it, (cast steel are cheaper) then the cost of bearings, install, etc.. Is your current 400 2 bolt or 4 bolt mains? In my view point, it's a wash. Your 400 might be of higher HP/TQ values than a 455 you can find, unless you are ready to shell out some major $.


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## Jim K (Nov 17, 2020)

another point of consideration.. With your current motor, you know what you have. A different motor, purchased from someone other than a reputable shop might have a host of issues you would just have to find out about the hard way.


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## Baaad65 (Aug 29, 2019)

Is your 400 in good shape, what if they find something not right while in there ?? Is it stock and do you want to keep it like that?? If stock and not pushing the motor maybe install a Eagle cast crank. Did you get a quote for all the labor? Watch out for "the while I'm in here and the motor is out maybe I should just make it a stroker" guy, he sneaks up on you and is hard to resist 😉


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## geeteeohguy (Feb 2, 2008)

I would take accurate measurements and have a machine shop machine a pilot bushing out of brass or bronze for you and run it. I did that back in 1979 with a GTO that I had that had a big car Pontiac engine and it worked perfectly. Cheap and effective. Cost me $12 back then, should be less than $100 in 2022 dollars. No worries.


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## 70 GTO (Oct 21, 2012)

My current 400 has 2 bolt mains. It has about 15,000 miles on it since the last rebuild. I don't drag race it at all but I do like to get on it at times.

The other thing about my current motor is the last owner had it built and I have very little info on it. I know that it runs fine and it is not numbers matching/original to the car (the car originally came with a 455). It has a comp cam in it (I don't know the specs) and everything else I know about it is on the outside like headers, intake, HEI. There is also an issue with an oil passage that I posted about a few months back, although I think it's fixed now.

Maybe some forum members can chime in if they know of a good 455 in central IL.

It's effectively been off the road for 2+ years already so hopefully that keeps the "while I'm in here" to a minimum. October will be the 10-year anniversary since buying it and I'd like to have it 100% by then.



geeteeohguy said:


> I would take accurate measurements and have a machine shop machine a pilot bushing out of brass or bronze for you and run it. I did that back in 1979 with a GTO that I had that had a big car Pontiac engine and it worked perfectly. Cheap and effective. Cost me $12 back then, should be less than $100 in 2022 dollars. No worries.


The pilot bearing for the TKX is a roller bearing (National 7109), so unfortunately I can't just have a bushing machined.


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## Baaad65 (Aug 29, 2019)

Got it, another flat lander welcome...I'm in Northwest IL.


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## Bopman (7 mo ago)

Baaad65 said:


> Got it, another flat lander welcome...I'm in Northwest IL.


I am a flat lander that got transplanted, at the age of 10, to Ky. ! Born in Champaign/Urbana.


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## Duff (Jan 12, 2020)

70 GTO said:


> My current 400 has 2 bolt mains. It has about 15,000 miles on it since the last rebuild. I don't drag race it at all but I do like to get on it at times.
> 
> The other thing about my current motor is the last owner had it built and I have very little info on it. I know that it runs fine and it is not numbers matching/original to the car (the car originally came with a 455). It has a comp cam in it (I don't know the specs) and everything else I know about it is on the outside like headers, intake, HEI. There is also an issue with an oil passage that I posted about a few months back, although I think it's fixed now.
> 
> ...


Why not?


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## O52 (Jan 27, 2019)

7109 is the factory pilot bearing used in Pontiac manual transmissions. Shielded on one side.
Does the TKX require a pilot bearing for warranty purposes? If so, make sure the bell housing is perfectly aligned.


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## Jared (Apr 19, 2013)

70 GTO said:


> My current 400 has 2 bolt mains. It has about 15,000 miles on it since the last rebuild. I don't drag race it at all but I do like to get on it at times.
> 
> The other thing about my current motor is the last owner had it built and I have very little info on it. I know that it runs fine and it is not numbers matching/original to the car (the car originally came with a 455). It has a comp cam in it (I don't know the specs) and everything else I know about it is on the outside like headers, intake, HEI. There is also an issue with an oil passage that I posted about a few months back, although I think it's fixed now.
> 
> ...


Best price you'll be able to get on a 455 would be through Len Williams.


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## geeteeohguy (Feb 2, 2008)

70 GTO said:


> My current 400 has 2 bolt mains. It has about 15,000 miles on it since the last rebuild. I don't drag race it at all but I do like to get on it at times.
> 
> The other thing about my current motor is the last owner had it built and I have very little info on it. I know that it runs fine and it is not numbers matching/original to the car (the car originally came with a 455). It has a comp cam in it (I don't know the specs) and everything else I know about it is on the outside like headers, intake, HEI. There is also an issue with an oil passage that I posted about a few months back, although I think it's fixed now.
> 
> ...


Sure you can, if the measurements are spot on. No worries.


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## PontiacJim (Dec 29, 2012)

70 GTO said:


> Hi Everyone,
> 
> I recently did a M21 to TKX swap in my car, and once I was finished I took it to my mechanic to look it over because I had concerns with the pilot bearing. Long story short, the hole in the back of the crankshaft is too large even for the oversize bearing that's available through Butler. My mechanic called a machine shop and they said all that can be done is to replace the crankshaft.
> 
> ...


I am not following what the issue is? If you had the Muncie in there, then that means you had a pilot bushing/bearing that had to fit. Installing the TKX should still mean that the pilot hole in the crank is the same and the pilot pin on the TKX is the same as the Muncie - unless something has been changed on the TKX that is not the same as the TKO. Found this for the TKX, mayb a Ford and not a GM input shaft?:

Input Shaft*1 1/8-inch*, either 10 or 26 spline; some Ford 1 1/16-inch 10-spline


Some cranks were not drilled for a pilot bushing, but since you had a Muncie already in the car, I have to assume that that is not the case - unless someone has made an adapter bushing to fit the crank and the Muncie into that. Maybe that's the issue?

FYI, Pontiac did use a bearing from the factory. Some like a factory bearing replacement, some like a bronze bushing replacement - personal choice on that one.

I get that you need to get the roller bearing versus pilot bushing per manufacturer, but I can't understand with all the TKO and TKX conversions why the issue in getting to correct bearing. How do all these other trans conversion suppliers like SilverSport, American Powetrain, and others sell a conversion kit that does not include the correct pilot bearing?

Call American Powertrain, not Butler, as American Powertrain has been doing these conversion, modifications, upgrades, and all you could ever want with a transmission conversion. Butler doesn't do transmission.

And as pointed out, you have to align the trans main shaft to the hole in the crank as the alignment can only be off a few thousands - the installation instructions should give you that tolerance. Most of the time, the bellhousing alignment is good, but you want to verify this or you can have issues with the transmission.

I would not be seeking another engine unless that is your goal. If worst came to worse, it would be very easy to get the OD of the hole in the end of the crank and take that dimension and your pilot bearing to a local machine shop and have them make a collar/spacer. The Spacer insert goes into the crank and the pilot bearing goes into the insert - problem solved and a lot cheaper than a $7,000.00 engine/rebuild unless that is what you want to do.









TKO VS TKX - American Powertrain


What are the differences? This article is to help you understand the basic differences in the TKO 5-speed and the new TKX that replaces it....Read More



americanpowertrain.com





Just my opinion.


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## geeteeohguy (Feb 2, 2008)

Typically these 5 and 6 speed transmissions allow .005" max runout at the bellhousing when it's all said and done. A properly fitted bronze or brass bushing will work fine here. 
The runout on my old Chevy was about .120" when I got it, and was enough to destroy the main shaft on my ST-10. The previous owner had installed the Lakewood can on top of a ground wire and it was far enough off that the w12 o'clock bolt would not fit. He also drove the dowel pins into the block. After rebuilding the trans, I was able to re-fit the pins and get everything square and ended up with .004" ....The ST-10, like the new 5 speeds and 5 speeds, is much tighter toleranced than the old Muncies, which have enough input slop to be able to 'soak up' slight mis-alignments. In my past experience, factory bellhousings are usually pretty much dead-on, while the scatter-can housings can be way off. 
One thing I learned that I did not know, is that when running a scatter can with a block saver plate, you need to run an extended pilot bushing to support the input shaft. This makes up for the 3/16" the trans is pushed away from the crank with the plate installed. As far as I know, they don't make extended bearings, only bushings. So what do the 5 and 6 speed guys who are running clutch cans use?? Here's a pic of my original main shaft...totally destroyed by mis-alignment.


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## Mine'sa66 (Oct 30, 2019)

PontiacJim said:


> I would not be seeking another engine unless that is your goal. If worst came to worse,* it would be very easy to get the OD of the hole in the end of the crank and take that dimension and your pilot bearing to a local machine shop and have them make a collar/spacer. * The Spacer insert goes into the crank and the pilot bearing goes into the insert - problem solved and a lot cheaper than a $7,000.00 engine/rebuild unless that is what you want to do.
> 
> 
> 
> ...


That^^^ was my exact thought.

Unless you're looking for a reason to do an engine swap?
If so, then absolutely, positively, there's no way short of a new engine that will solve this


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## 70 GTO (Oct 21, 2012)

The pilot bushing that was in there with the muncie was the bronze oil impregnated bushing. When I pulled the muncie, the bushing fell out of the hole and it was very damaged. There's also marks on the crankshaft in the area where the bearing is pressed in where someone tried to gouge it to build up space to make a tighter fit. So I think this car has had pilot bushing sizing issues for a long time. 

There is no issue with the size of the transmission input shaft fitting into the pilot bearing. This is strictly the bearing not fitting tightly enough into the crankshaft on the engine. 

I know very little history on the motor so maybe it has a crank for an automatic in it and that's what caused this.

I ordered the TKX kit from SST so I will have to call them this week to see if a bearing is strictly necessary, or if a bushing will be ok (for warranty purposes). I also need to ask my mechanic why the machine shop said nothing more could be done short of pulling the crank. Not sure why the machine shop couldn't make a collar/spacer so the issue may be more complicated than I remember.

Alignment is all good. Spec is 0.005 and it measured as 0.0005 (note extra zero). SST required alignment for warranty. See the attached picture. I used the adjustable dowel pins SST offers.


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## lust4speed (Jul 5, 2019)

When I got my TKO from SST they goofed and sent me a Chevy Bronze pilot bushing instead of the Pontiac bearing. So there is no reason why a bushing isn't acceptable since some of their kits come with one. There should be absolutely no problem in turning down a larger bushing. Plus, if you do have a warranty issue how would they know what pilot bushing/bearing you were running unless you tell them.


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## PontiacJim (Dec 29, 2012)

70 GTO said:


> The pilot bushing that was in there with the muncie was the bronze oil impregnated bushing. When I pulled the muncie, the bushing fell out of the hole and it was very damaged. There's also marks on the crankshaft in the area where the bearing is pressed in where someone tried to gouge it to build up space to make a tighter fit. So I think this car has had pilot bushing sizing issues for a long time.
> 
> There is no issue with the size of the transmission input shaft fitting into the pilot bearing. This is strictly the bearing not fitting tightly enough into the crankshaft on the engine.
> 
> ...



Sounds like the crank may have been an automatic and did not have the crank drilled for the manual trans. If someone tried to open up the hole using a die grinder and carbide bit, they most likely made a mess of it. The other concern would be that the smaller hole that the "alignment pin" on the input shaft may not be deep enough. They may have been able to fit the dowel into the bushing, but if it is jamming into the crank, it will force the crank forward into the thrust bearing and rapidly wear it out, not to mention wear out the front bearings in the Muncie.

The Muncie trans uses ball bearings while the TK trans uses taper bearings. Ball bearings are more forgiving and provide more play, but taper bearings are more exacting and this is why the tolerance per your instructions must be followed. The needle thrust bearing is also more precise and I believe I read that the input shaft's use a different material than the old Muncie's and is another reason why the roller bearing is suggested over the bronze bushing. Again, follow the TK instructions so you don't lose your warranty should something go wrong.

I imagine the TKX is the same, but improved, TKO and you will also have to "break in" the transmission for a few miles before hammering on it.


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## 70 GTO (Oct 21, 2012)

Well I visited the shop last Monday before I flew out to Monterey car week, and they had already disassembled the motor the Friday before. I took a few pics. Visited today too (didn't take pictures) and they showed me that the front of the cam was cutting into the timing cover, so it's just as well that they tore into it. They got the new crank delivered and are just waiting on some gaskets now, and figuring out the cam issue.


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## PontiacJim (Dec 29, 2012)

70 GTO said:


> Well I visited the shop last Monday before I flew out to Monterey car week, and they had already disassembled the motor the Friday before. I took a few pics. Visited today too (didn't take pictures) and they showed me that the front of the cam was cutting into the timing cover, so it's just as well that they tore into it. They got the new crank delivered and are just waiting on some gaskets now, and figuring out the cam issue.
> 
> View attachment 156713
> 
> View attachment 156712


You may want to read the section on the cam's thrust plate and measuring the clearance. Might apply to the cam hitting the cover. Could be the fuel pump eccentric was not seated correctly?









DISTRIBUTOR GEARS & DIZZY INSTALLATION


Did some research on distributor gears and this is the best I could put together using several internet sources to include the cam makers. Pic # 1 - In stock form, the only oil that lubricates the spinning cam and distributor gears gets there by the splash effect, but the distributor also has...




www.gtoforum.com


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## Baaad65 (Aug 29, 2019)

By looks of that shop and the cars in it I think you're in good hands 👍


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