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Engine swap headaches
https://slantsix.org/forum/viewtopic.php?t=67470		 Page 1 of 2
Author:  trevorsworth [ Thu Oct 19, 2023 7:18 pm ]
Post subject:  Engine swap headaches
Hey guys, I recently bought a rebuilt 225 to replace the very tired (300k miles) 225 in my 71 Dart, which has a 904 auto.

This engine has a 1985 block, hydraulic lifters, bored .060 over, supposedly some kind of custom cam, most of a super six setup (I didn't get the kickdown) and less than 1000 miles on it. That should make it a pretty good upgrade for my car.

Everything seemed great until we went to actually put it in. I figured I'd use the brand new torque converter that was already bolted to the engine. Went to fit it up to the transmission, no joy. Figured out the shank was wrong, grabbed the old torque converter and put it in. Swung the engine over into the engine bay, got it lined up, got a couple bolts in but could not get the engine to sit all the way back with the bellhousing. Noticed the crank pulley wouldn't turn, figured the old torque converter didn't like the new flex plate and was binding. We pulled them back apart to free everything up. It was getting late so we aborted for the night.

This engine was built for use in a 1964 Dart with a push-button transmission (which I have, but of course won't work in my car). I have done a little research tonight and I learned there are generational differences between the crankshafts, torque converters, input shafts, pumps etc. I guess that he must have used an early crank when building this engine so that he could use the 64's push-button transmission.

I really don't want to pay what it will cost to have a torque converter custom built for this engine. I haven't had an opportunity to look at anything yet since learning about the generational changes (the car is sitting at work). Is the crank register/torque converter snout a critical area for tolerances? Can I just hog out the register on the crank to make it fit? I am a surgeon with a dremel tool. :P Is there some other solution? I am lazy and don't really want to rip apart the transmissions to swap the guts around to be able to use the torque converter, but I guess if I really have to I can.
Author:  Charrlie_S [ Fri Oct 20, 2023 5:17 am ]
Post subject:  Re: Engine swap headaches
Something doesn't make sense. A 1985 slant six should have a "cast" crank with the large converter bore. All cranks with the small converter bore were forged, and do not fit the later block without special machine work (not likely done). Look in the end of the crank, and see if there is a "reducer" bushing installed to allow the later engine to be used with the early transmission. If there is a bushing in there, remove it, and then the engine should bolt up to the 71 trans and 71 converter.
Author:  trevorsworth [ Fri Oct 20, 2023 10:49 am ]
Post subject:  Re: Engine swap headaches
Quote:
Something doesn't make sense. A 1985 slant six should have a "cast" crank with the large converter bore. All cranks with the small converter bore were forged, and do not fit the later block without special machine work (not likely done). Look in the end of the crank, and see if there is a "reducer" bushing installed to allow the later engine to be used with the early transmission. If there is a bushing in there, remove it, and then the engine should bolt up to the 71 trans and 71 converter.
I learned about the adapter bushing last night & was optimistic but looking at it now, that doesn’t seem to be the case. The crank is definitely the small bore type.
Author:  Charrlie_S [ Fri Oct 20, 2023 11:23 am ]
Post subject:  Re: Engine swap headaches
I can't think of anything other than removing the oil pan and verifying if the block is really a cast crank block, and whether the crank is a cast or forged piece. Then going from there. You could remove the crank and have the pocket bored out or replace the crank with one that will work. I would not try to open the crank pocket by hand. It needs to be almost perfectly centered, or you can damage parts.
PS: What size is the hole in the flexplate that fits the crank? Is it 1.96 inches in diameter, or 2.16 inches?
Author:  trevorsworth [ Fri Oct 20, 2023 11:46 am ]
Post subject:  Re: Engine swap headaches
Quote:
I can't think of anything other than removing the oil pan and verifying if the block is really a cast crank block, and whether the crank is a cast or forged piece. Then going from there. You could remove the crank and have the pocket bored out or replace the crank with one that will work. I would not try to open the crank pocket by hand. It needs to be almost perfectly centered, or you can damage parts.
PS: What size is the hole in the flexplate that fits the crank? Is it 1.96 inches in diameter, or 2.16 inches?
Looks like 2 1/8 according to my measuring tape.
Author:  Charrlie_S [ Fri Oct 20, 2023 11:50 am ]
Post subject:  Re: Engine swap headaches
Quote:
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I can't think of anything other than removing the oil pan and verifying if the block is really a cast crank block, and whether the crank is a cast or forged piece. Then going from there. You could remove the crank and have the pocket bored out or replace the crank with one that will work. I would not try to open the crank pocket by hand. It needs to be almost perfectly centered, or you can damage parts.
PS: What size is the hole in the flexplate that fits the crank? Is it 1.96 inches in diameter, or 2.16 inches?
Looks like 2 1/8 according to my measuring tape.
That is the late crank size. Can you measure the pocket in the end of the crank? 1.81 dia, or 1.55 dia.
Author:  trevorsworth [ Fri Oct 20, 2023 12:05 pm ]
Post subject:  Re: Engine swap headaches
Quote:
Quote:
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I can't think of anything other than removing the oil pan and verifying if the block is really a cast crank block, and whether the crank is a cast or forged piece. Then going from there. You could remove the crank and have the pocket bored out or replace the crank with one that will work. I would not try to open the crank pocket by hand. It needs to be almost perfectly centered, or you can damage parts.
PS: What size is the hole in the flexplate that fits the crank? Is it 1.96 inches in diameter, or 2.16 inches?
Looks like 2 1/8 according to my measuring tape.
That is the late crank size. Can you measure the pocket in the end of the crank? 1.81 dia, or 1.55 dia.
I can’t get an inside measurement, but the flex plate on my ‘71 engine has a bigger opening than this one. Would a phone call be easier?
Author:  Charrlie_S [ Fri Oct 20, 2023 12:22 pm ]
Post subject:  Re: Engine swap headaches
Quote:
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Looks like 2 1/8 according to my measuring tape.
That is the late crank size. Can you measure the pocket in the end of the crank? 1.81 dia, or 1.55 dia.
I can’t get an inside measurement, but the flex plate on my ‘71 engine has a bigger opening than this one. Would a phone call be easier?
Yes. I'll pm my number to you.
Author:  trevorsworth [ Fri Oct 20, 2023 3:42 pm ]
Post subject:  Re: Engine swap headaches
Quote:
Quote:
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That is the late crank size. Can you measure the pocket in the end of the crank? 1.81 dia, or 1.55 dia.
I can’t get an inside measurement, but the flex plate on my ‘71 engine has a bigger opening than this one. Would a phone call be easier?
Yes. I'll pm my number to you.
I'm still not sure exactly what's going on with these parts but I knew that I had one torque converter that fit the transmission and one that fit the crankshaft. I took them both to the local transmission shop and asked them to make one from the two that will work. The guy there is a longtime Mopar nut and knew exactly what I was talking about so I think it will work out fine. I am not sure if I looked at the numbers on the block wrong or what, but I was pretty sure it was an '85 dated motor. Maybe the guy that built it wanted to run that forged crank to cope with the awesome power I'm sure this thing will be cranking out... :roll: :P

If there is a problem with the new motor I should be able to put my old tired motor back in for now & use the modified torque converter with an adapter bushing.
Author:  Charrlie_S [ Fri Oct 20, 2023 5:24 pm ]
Post subject:  Re: Engine swap headaches
Your TQ guy may know what you are talking about, but something is still wrong. If the crank accepts the flex plate with the big center hole, it has to have the large pilot hole. I know what your converter guy is going to do, but you posted you didn't want to do a special converter. I have that type converter in my 66 Valiant, and another brand new one on the shelf.
Author:  trevorsworth [ Fri Oct 20, 2023 5:43 pm ]
Post subject:  Re: Engine swap headaches
Quote:
Your TQ guy may know what you are talking about, but something is still wrong. If the crank accepts the flex plate with the big center hole, it has to have the large pilot hole. I know what your converter guy is going to do, but you posted you didn't want to do a special converter. I have that type converter in my 66 Valiant, and another brand new one on the shelf.
I will take some measurements again tomorrow. The one I measured at 2 1/8" is off the new engine, and it is smaller than the one on the old tired engine. Having said that... I do work at an auto shop but somehow we do not have calipers, so that measurement was taken with a really crappy measuring tape and there is no telling if it is right.

What I really didn't want to do was rip both transmissions (the late one in my car and the early one that came with this engine) apart to switch the input shaft & pump, which I think I read somewhere was the only way to solve this problem without a custom torque converter? Not sure if that is accurate. I didn't realize that cutting up two torque converters to make one was an option until today, I thought it was a scratch-build sort of thing. I have not really delved this deep into a car yet so I'm still learning as I go. The only other time I have split an engine off a transmission it was an early Ford flathead with a 3-speed manual.
Author:  Charrlie_S [ Sat Oct 21, 2023 5:13 am ]
Post subject:  Re: Engine swap headaches
Don't know how close you are to Harbor Freight
https://www.harborfreight.com/6-in-digi ... liper+tool
Good investment
Author:  Charrlie_S [ Sat Oct 21, 2023 5:24 am ]
Post subject:  Re: Engine swap headaches
Quote:

What I really didn't want to do was rip both transmissions (the late one in my car and the early one that came with this engine) apart to switch the input shaft & pump, which I think I read somewhere was the only way to solve this problem without a custom torque converter?
. Most of my engines have the early crank, with the small converter pocket. But I have some with the large pocket. I also have early and late transmissions. So I usually have my converters built with the small pilot (for the early crank) and the large splines (lor the late transmission). That way I can use the converter on any combination I want.
early engine/late trans........ as is
late engine/late trans...........bushing in the crank pocket
early engine /early trans....... use the late trans input parts
late engine/early trans........ bushing in the crank and late trans input parts
Author:  trevorsworth [ Sat Oct 21, 2023 10:50 am ]
Post subject:  Re: Engine swap headaches
Quote:
Quote:

What I really didn't want to do was rip both transmissions (the late one in my car and the early one that came with this engine) apart to switch the input shaft & pump, which I think I read somewhere was the only way to solve this problem without a custom torque converter?
. Most of my engines have the early crank, with the small converter pocket. But I have some with the large pocket. I also have early and late transmissions. So I usually have my converters built with the small pilot (for the early crank) and the large splines (lor the late transmission). That way I can use the converter on any combination I want.
early engine/late trans........ as is
late engine/late trans...........bushing in the crank pocket
early engine /early trans....... use the late trans input parts
late engine/early trans........ bushing in the crank and late trans input parts
I went and bought calipers. The smaller one (off the new engine) is 1.96 inches.
Author:  Charrlie_S [ Sat Oct 21, 2023 1:00 pm ]
Post subject:  Re: Engine swap headaches
Quote:

I went and bought calipers. The smaller one (off the new engine) is 1.96 inches.
OK, that means the crank pocket is 1.55 inches, which is the early (1960-1967) crank. So your two options are Get a modified converter, with the small pilot and large spline, or convert the trans to small input shaft, which I don't recommend. Or change the crank to a 1968 to 1976 crank
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