PLEASE HELP ASAP W/ 360 to 401 swap

[khurst]

Just installed my 401 in my 89 Grand problem is every time I pull the bell housing on the 727 tranny down snug I cant turn the engine over. Loosen it up a bit(about 1/4 inch) and it turns over fine(with a wrench). Also my torque converter bolts are not long enough any more. Seems like the torque converter is not seating all the way into the crank shaft. I checked before I installed and it looked like they were the same size holes(the old 360 and the 401 crank). Has anyone got any advice? I didnt disturb the torque converter prior to installing the 401 even if I had seems the flexplate would be hitting the torque converter, not a 1/4 inch shy of the flexplate were the bolts go through??? PLEASE help!!!
Thanks in advance,
Kirk Hurst

[bvibert]

The 401 probably had a TH400 behind it. I think that either the 400 or the 727 had to have a bushing in the crank to account for different size TC. I'm guessing that it was the 400 that needed a bushing and that its in the 401 crank causing the 727 TC not to seat all the way. I also think that the flex plates are different for 727 and 400...

Someone please correct me if I'm wrong...

[ December 03, 2002, 04:45 PM: Message edited by: bvibert ]

[tc]

what did you get the 401 out of? It sounds like what bvibert said. I haven't got a straight awnser about the flex plate (weather you can use the old one or not) but you can but one for a 72 matador for about $50, it came with the 401 t727 combo.

[tc]

autozone has it. heres the part #fra-305 and its a flexplate for a 1972 AMC matador with a 401. How was the swap? I'm getting ready to swap my 401 in so I was just curious.thanks

[joe]

The above is correct. If the 401 came from a FSJ it came w/TH400 behind it and it does have an insert/pilot bushing in the crank that needs to be removed before bolting a 727 behind it. You will also need a 401/727 flexplate.

[khurst]

The 401 is a long block from S&S machine in spokane WA. with the 7 year warenty. Checked for bushings there were none in the crank. I think what is happening is the same thing that happend to me with my 360 swap into my CJ-5. The torque converter is being pressed into the crank and without any rotation the thing doesnt seat all the way. What I am going to do is start it up (once I get the intake on) and put it in gear with out any converter bolts in and let the torque converter seat in with it in gear and slowly pull the tranny bell housing down on to the block. This is what I had to do with my CJ but it was a standard vice auto. Does this sound alright? Thanks for the replies!! Let you guys know how it all turns out tomarrow.

[Bob Barry]

:eek:

If your transmission is not mating snug against the engine block WITHOUT you using the bellhousing bolts to draw it down, then something is MAJORLY screwed up.

First, make sure your torque-converter is FIRMLY seated in the transmission. When the transmission is tighened down to the engine, the torque-converter MUST have some play to move back and forth and also turn slightly.

As for the crank bushing, it doesn't look like a bushing. It's so thin and usually just appears to be part of the crankshaft pilot hole. It is a very thin sleeve, more than a bushing. If it's in there and you forced your transmission to attach to the engine with the bellhousing bolts, there is a very good chance that you have damaged or destroyed the front pump in your TF727 transmission. You can fix that with the tranny still in the truck, once you pull the engine out.

Also, the flexplate on the 401 must be one balanced for a 401, but no factory flexplates will mate with your '89's Mitsubishi starter. The solution is to either convert the wiring and starter over to a Ford-style starter, or get a special flexplate. I believe some of the AMC performance shops stock those.

[Agent Orange]

Bob: I have an 80 Cherokee with a 401 and 727. The previous owner set this up. Everytime I start the truck there is an awful noise from the starter, but it quits after it disengages. I have had 3 diff starters in there and they all sound bad. I'm thinking it's a flexplate issue (bad teeth), but I'm unsure. Will I be okay in swapping in a Matador flexplate to see if this cures the problem. Thanks

[mdill]

Personally , I would in no way recomend starting the engine to try and seat the
converter. The best guess is the TH400 bushing is still in the crank ! pull the engine
out far enough to measure the bore on the crank and the converter snout, someone
on the board will have the specs on what the values should be.

Mike D.

[Mike B]

Originally posted by Bob Barry:

Also, the flexplate on the 401 must be one balanced for a 401, but no factory flexplates will mate with your '89's Mitsubishi starter. The solution is to either convert the wiring and starter over to a Ford-style starter, or get a special flexplate. I believe some of the AMC performance shops stock those.[/QB]Bob,
I know the factory 401's existed way before the Japanese starters,but if your above quote is true,are you saying that Chrysler changed the design of the 360 flexplate(or something else in the starter set-up) when they went from the Ford design starter to the Mitsubishi starter?

I didn't think(someone correct me if I'm wrong) there was any difference in a 360 to 727
flexplate and a 401 to 727 flexplate EXCEPT for the balance weight.

Please elaborate as I'm planning a 401 swap into my 360 Grand Wag also, and this is the first time I've heard of a 401 flexplate not mating with the late starter.....

Thanks! smile.gif

Mike B

[Andrew]

DO NOT START IT!!!!! Check to make sure you also didn't crack your pump gears on the tranny when you snugged down the bolts without it seated. MAKE SURE your TC has been seated down all 3 notches in the 727, count em. It might take some doing, they can be stubborn. I made this mistake on a ford C4 at a young age and detonated the pump gears doing what you are proposing.

[Bob Barry]

There were two different flexplates that Jeep used to mate its 360's to the TF727 trannies: the more common one used from '80-'87, which mated to the Ford starter, and which was also used in the '72-'80 (or so) AMC 360 car applications when the engine was mated to the TF727.

There was also the flexplate used from '88-'91 to mate the 360 to the TF727 when using the Mitsubishi starter.

The difference between the two is not readily apparent to the naked eye. I think they are the same tooth count, but that they differ in the depth of the teeth relative to the crank-flange mating surface. I've got at least one of each of these around, so I should compare them and see what's what.

As for the 401, each AMC engine size uses its own flexplate, so the 360 flexplate can't be re-used with the 401. 401's put into the '80-'87 FSJ's can use the flexplate used in AMC automotive applications from '72-'74, when they bolted the engines to TF727's and used the Ford starter.

There was no factory application for a TF727 mated to the 401 that would also use the Mitsubishi starter. That's why you have to turn to the aftermarket for that application. I think it was Peformance American Style or one of those suppliers who carried them.

[Mike B]

Thanks for the detailed info Bob..
I'll talk to the vendors about this one...

Mike B