Auto to Manual? (Sort of)

[JGizmo]

Hey all, I'm in the process of swapping my blown up 170 slant six to a 225 slant six. The issue I'm having is that the old engine paired to a three speed manual transmission, while my new engine was bolted to an automatic. I'm planning on hooking the new engine up to my manual transmission. Is there a way to swap the flex plate out for the flywheel/clutch setup that was on the old engine?

View attachment 1715896807

 

[royslead]

Start by un-bolting it all.I'm not sure,if the crank on the newer engine will accept a pilot bearing that would probably be the biggest hurdle. Others with /6 experience will chime in.

 

[valiantwagonguy]

It's almost a sure thing that the crank is drilled for a pilot .The problem you will have is most likely in the flywheel.The register on the back of the crank was enlarged from 2 IN to 2 1/8 or so . This means you will need another flywheel or have yours machined to fit . Good news is that slant 6 flywheels are out there by the millions

 

[Charrlie_S]

First off, What year is the 170 engine? What year is the 225 engine? Makes a difference.
Next, All slant six engines were "drilled" for a pilot bearing, but not all were "reamed" to the finished size.
The size of the center hole in the flywheel/flexplate changed between 1967 and 1968, so you need the flywheel to fit the crank.
If your "new" engine is later then 1967, and the pilot bushing does not fit the hole, you can use the pilot bearing from a Dakota. (or you can ream the crank hole, or have the pilot bushing OD turned down to fit).

 

[JGizmo]

Start by un-bolting it all.I'm not sure,if the crank on the newer engine will accept a pilot bearing it at would probe the biggest hurdle. Others with /6 experience will chime in.

Thanks for the advice

 

[JGizmo]

It's almost a sure thing that the crank is drilled for a pilot .The problem you will have is most likely in the flywheel.The register on the back of the crank was enlarged from 2 IN to 2 1/8 or so . This means you will need another flywheel or have yours machined to fit . Good news is that slant 6 flywheels are out there by the millions

Thanks for the info! I think a flywheel is going to be easier to find than a pilot bearing.

 

[JGizmo]

First off, What year is the 170 engine? What year is the 225 engine? Makes a difference.
Next, All slant six engines were "drilled" for a pilot bearing, but not all were "reamed" to the finished size.
The size of the center hole in the flywheel/flexplate changed between 1967 and 1968, so you need the flywheel to fit the crank.
If your "new" engine is later then 1967, and the pilot bushing does not fit the hole, you can use the pilot bearing from a Dakota. (or you can ream the crank hole, or have the pilot bushing OD turned down to fit).

The 170 came out of my '65 Valiant. The 225 came out of a '66 Valiant.

 

[Professor Fate]

The 170 came out of my '65 Valiant. The 225 came out of a '66 Valiant.

In that case, you should be good to go. Everything should bolt up, but as said above, you MAY have to finish ream the crank for the pilot bushing, or have the bushing OD turned down a bit. NAPA offered a reduced OD pilot bushing for this at one time, not sure if they still do.

 

[Charrlie_S]

The 170 came out of my '65 Valiant. The 225 came out of a '66 Valiant.

You are golden. Every thing from the 170 will fit the 225, except possibly the pilot bushing. You will need to buy a new pilot bushing and measure the OD, and the ID of the hole in the crank. If the OD is too large to fit, have a machine shop turn down the OD of the bushing. The NAPA "fix" bushing has not been available for several years, and buying a reamer to finish the ID of the crank is VERY expensive.

 

[JGizmo]

In that case, you should be good to go. Everything should bolt up, but as said above, you MAY have to finish ream the crank for the pilot bushing, or have the bushing OD turned down a bit. NAPA offered a reduced OD pilot bushing for this at one time, not sure if they still do.

Thank you!

 

[JGizmo]

You are golden. Every thing from the 170 will fit the 225, except possibly the pilot bushing. You will need to buy a new pilot bushing and measure the OD, and the ID of the hole in the crank. If the OD is too large to fit, have a machine shop turn down the OD of the bushing. The NAPA "fix" bushing has not been available for several years, and buying a reamer to finish the ID of the crank is VERY expensive.

Thanks for the help. Just to be clear you are saying I can buy a new bushing for a 225 and turn down the OD, correct?

 

[valiantwagonguy]

If it is a 66 engine why is it blue? Blue factory paint started in 70 .Just because it came out of a 66 doesn't make it a 66 motor.Check the code on the pad on the deck just under the head behind where the coil bolts to the motor.If it's a 66 it will have the letter B stamped at the beginning of the series of numbers ( B 225 123456 ).Your 65 motor should have A stamped in it (A 170 123456) You need to know what you have before moving forward.A 66 225 will be drilled even if it was in front of an automatic. I've never seen one that wasn't from that era .

 

[JGizmo]

If it is a 66 engine why is it blue? Blue factory paint started in 70 .Just because it came out of a 66 doesn't make it a 66 motor.Check the code on the pad on the deck just under the head behind where the coil bolts to the motor.If it's a 66 it will have the letter B stamped at the beginning of the series of numbers ( B 225 123456 ).Your 65 motor should have A stamped in it (A 170 123456) You need to know what you have before moving forward.A 66 225 will be drilled even if it was in front of an automatic. I've never seen one that wasn't from that era .

I checked and the code starts with B 225. After some digging with a screwdriver I found red flakes underneath the blue. Thank you for the help!

 

[Charrlie_S]

Thanks for the help. Just to be clear you are saying I can buy a new bushing for a 225 and turn down the OD, correct?

If necessary. Some cranks were reamed to the correct size for the pilot bushing, some were just drilled and not reamed to finished size.

 

[JGizmo]

If necessary. Some cranks were reamed to the correct size for the pilot bushing, some were just drilled and not reamed to finished size.

Okay cool thank you.

 

[valiantwagonguy]

Every early slant I ever pulled had a factory installed pilot bushing in it. So before you start looking to get one why don't you remove the automatic trans flex plate and have a good look at the end of the crank.Take a close up photo of the back of the crank and post it. Lets see what you have. As far as getting a bushing if you need it,they can be had at any good auto parts store for under 10 bucks

 

[JGizmo]

Every early slant I ever pulled had a factory installed pilot bushing in it. So before you start looking to get one why don't you remove the automatic trans flex plate and have a good look at the end of the crank.Take a close up photo of the back of the crank and post it. Lets see what you have. As far as getting a bushing if you need it,they can be had at any good auto parts store for under 10 bucks

Hey sorry for the late reply. It looks like my new engine does not have the bushing. I bought a new bushing, and it sits almost flush with the hole. Should I have to hammer it in? Thanks.

 

[valiantwagonguy]

You have to clean up that rust.Nothing is going in with all that rust . A wooden dowel with some 120 grit paper then some scotch bright pad work should do it .The bushing is an interference fit so yes you have to tap it in . I usually use an old input shaft to do this. It needs to be snug in there but not really tight so don't beat it in otherwise you will damage it and the shaft won't fit in it properly because the id will shrink and cause it to bind . Sometimes what I do is put the new bushing in the freezer for a couple hours before installation . This will shrink it some and it will expand to it's normal size as it warms . A very small ball hone will really clean the crank out best.

 

[valiantwagonguy]

You have to clean up that rust.Nothing is going in with all that rust . A wooden dowel with some 120 grit paper then some scotch bright pad work should do it .The bushing is an interference fit so yes you have to tap it in . I usually use an old input shaft to do this. It needs to be snug in there but not really tight so don't beat it in otherwise you will damage it and the shaft won't fit in it properly because the id will shrink and cause it to bind . Sometimes what I do is put the new bushing in the freezer for a couple hours before installation . This will shrink it some and it will expand to it's normal size as it warms . A very small ball hone will really clean the crank out best.View attachment 1715899406

You can get these small hones on line . Just measure the OD of the bushing and get one that size or very slightly largerhttps://www.amazon.com/dp/B00DB89S6A/?tag=fabo03-20

 

[Killer6]

I'd start on that mess with a plumbing pipe brush, & it looks like a ridge part-ways down the bore, that may not be finish reamed to size. You have to drive the bushing in yes, & if You are persistant enough, it's possible to drive a bushing into an un-finished bore.....the shaft end will not go in however because it swedges the bushing down.... Gauge the bushing & bore after cleaning & before pounding away.

 

[valiantwagonguy]

I just looked close at the last photo and it looks like there is a bushing already in place.Look at the outside diameter of the hole and you will notice a circle about a 16th round that goes around the hole.That looks like the thickness of a bushing.Clean it all up and see if that is bronze

 

[JGizmo]

I just looked close at the last photo and it looks like there is a bushing already in place.Look at the outside diameter of the hole and you will notice a circle about a 16th round that goes around the hole.That looks like the thickness of a bushing.Clean it all up and see if that is bronze

I cleaned the rust a little bit and took some more photos. Does it look like a bushing is already in there? If it helps I took a photo of the old engine's bushing.

 

[valiantwagonguy]

The last one sure does ! Is that your old motor or the 66? Now that it's clean how does the bushing feel as you try to put it in? Clean up the hole real good with light sand paper ,oil it lightly and try to gently knock it in with a block of wood .Don't hit the bushing directly with a tool like a hammer. It should go in with some resistance but you shouldn't have to beat it in.

 

[JGizmo]

The last one sure does ! Is that your old motor or the 66? Now that it's clean how does the bushing feel as you try to put it in? Clean up the hole real good with light sand paper ,oil it lightly and try to gently knock it in with a block of wood .Don't hit the bushing directly with a tool like a hammer. It should go in with some resistance but you shouldn't have to beat it in.

That last picture was the old motor, the bushing went in on the new one although I used a socket to hammer it in, which seems to have warped the very front edge.

 

[Killer6]

The bushing went in although I used a socket to hammer it in, which seems to have warped the very front edge.
View attachment 1715899684 View attachment 1715899685 View attachment 1715899686

Yeah, You bunged it up a bit, get a half-round file & deburr/remove the displaced material. Should be fine.