Strange Starter Problem

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T56MaxTorq

T56MaxTorq

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Hey guys, have an LA360 on a test stand and cannot get the starter to engage the torque converter gear, the overunning clutch hits the flexplate. A 904 is hooked up behind it, with a 904 torque converter and a b&m flexplate that has a cutout for use with an external balance 360 with a 318 converter. With out confusing anyone too much, I have this engine for my truck, trying to fire it up on a test stand. To start the thing I used my old duster 904 without any guts. I've ran this exact flexplate with this exact same block and starter but my trucks 727 behind it. What can I be doing wrong? I thought these transmissions were the same, but the guts were different. The 904 I have hooked up was attached to another 360. I can physically see the the starter solenoid plung the overunning clutch into the flexplate before the gear even splines in. It would take at least .050 to clear the overunning clutch from the flexplate. Pretty stumped on this one guys!
 
the only things i can think of is that the 904 either is not mounted completely tight and all the way on the dowel pins or the 904 case was warped or poorly machined from the factory causing the starter to sit crooked enough that it wont engage the flywheel
 
That's what I'm thinking now. The bolts are all tight and the dowel pins aligned. Well, pulled the trans off and the tq, the flexplate is on correctly, it has a stamp on it that says engine side only. I am going to buy a magnum starter and try that. Maybe the clutch on it is a little smaller..in fact i think the whole thing is a little smaller which I need to help clear some headers.
 
This is a 727 flexplate with a 904 trans? Don't think that works
 
when you say you are using a guted 904 case, do you at least have a front pump installed in the case to support the torque converter? Just wondering.
 
Loosen the top starter bolt. Take the bottom bolt all the way out. Swing the bottom toward the outside of the bell housing. See if there is another bolt hole farther out. I have run into this a time or two. Not sure what the other bolt hole is for. ( the one closest to the center of trans.) Edit: Seems like I remember seeing 3 bolt starters maybe?
 
Do you have the dust cover sandwiched between starter and the bell housing? The starter will grind without it.
 
moe7404 said:
your trouble is you are using a B&M product, toss it. find a good brand.
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wooooow .....it must just be installer cus whoever did mine has evreything great, u cant have non consistant shifts and be a 12sec track champ 2years in a row . either that or i got lucky
 
Correct me if I'm misunderstanding you but are you saying your using a flexplate made for a 727? If so, your probably also using a 727 converter, correct? 727 converters are larger diameter than a 904 converter and have 8 more teeth on the ring gear. If you are trying to use a 727 flexplate and converter from a 727 in a 904 case it won't work because the larger ring gear puts the teeth farther out from where they should be.
 
moe7404 said:
your trouble is you are using a B&M product, toss it. find a good brand.
Click to expand...

Rude..it's a glorified piece of sheetmetal, i think it'll last.

The tq is not supported by the pump..i didn't see any reason to support it, maybe this was a mistake..who knows. There isn't another bolt hole to use unfortunately and the dust shield is installed.
 
fishy68 said:
Correct me if I'm misunderstanding you but are you saying your using a flexplate made for a 727? If so, your probably also using a 727 converter, correct? 727 converters are larger diameter than a 904 converter and have 8 more teeth on the ring gear. If you are trying to use a 727 flexplate and converter from a 727 in a 904 case it won't work because the larger ring gear puts the teeth farther out from where they should be.
Click to expand...

I didn't know they were different diameters but Im using a 727 plate, 904 converter and a 904 case. This must have been the proble. And for the record, this is just for testing/leak checks. The final product is all 727.

The magnum starter works great. It's smaller and doesn't have a huge overturning clutch getting in the way. Thanks again guys!

Always learning something!
 
T56MaxTorq said:
I didn't know they were different diameters but Im using a 727 plate, 904 converter and a 904 case. This must have been the proble. And for the record, this is just for testing/leak checks. The final product is all 727.
Click to expand...

Glad you got it working. I understood it's for use on a engine stand. Got one myself but I used a bellhousing and flywheel. Made mounting the back of the engine real easy.
 
fishy68 said:
Correct me if I'm misunderstanding you but are you saying your using a flexplate made for a 727? If so, your probably also using a 727 converter, correct? 727 converters are larger diameter than a 904 converter and have 8 more teeth on the ring gear. If you are trying to use a 727 flexplate and converter from a 727 in a 904 case it won't work because the larger ring gear puts the teeth farther out from where they should be.
Click to expand...

'S what I was tryin' to say earlier

67Dart273 said:
This is a 727 flexplate with a 904 trans? Don't think that works
Click to expand...
 
Not sure if this is a bit late lol but I’m in the middle of this swap now, and am finding out that depending on the years, the starter for the a904 sit about a half inch lower, so the 2 trannies do not use an identical starter... or so I’m told as I need a new starter for a ‘77, if I’m wrong, can someone give me a CERTAIN answer? Lol
 
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