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strange T-350 problem

6K views 17 replies 6 participants last post by  49chevysd 
#1 ·
Hey guys,
I frequently read the boards but rarely post, but im just plain stumped so thought I would ask for some help. A little history:

I had what I believe to be a 1978 Olds 403 SBC motor mated to a th350 transmission. The transmission had a lot of metal shavings in the pan, so I figured I should swap it out. So I purchased another th350 from a local hot rod swap that was a fresh rebuild. Motor and tranny went together fine. 6 months later, I blew the motor.

So I had a 350 sbc sitting in the corner and figured it was a good time to start using that. So I yanked out the 403 and stroked the 350 to 383. The 383 is a 1974 block, so i figured the transmission would fit the new motor. But I seem to be wrong. Rather than encountering the common problem of having too much space between the flexplate and converter, I have the opposite problem. It 'feels' like the transmission is properly seated on front shaft. I called the shope I bought the stroker kit from (and the shop that did the machine work on the motor) and both say I shouldnt have any problems. I have tried 3 different converters and none of them fit. I still have ~3/4" between the bell housing and the block after the converter is seated against the flexplate.

Any suggestions would be GREATLY appreciated. Sorry to be long winded but i am pulling my freaking hair out, so I have come to ask the you guys who know way more about this than I do. thanks!!

-49chevysd
 
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#2 ·
I`am thinking the converter is not engaged with the pump gear properly! push the converter into the tranny while rotating it in either direction! when it engages the two notches in the hub end the converter should be recessed about and inch behind the tranny bolt face? bolt the housing to the block, then move the converter forward to the flexplate
 
#4 ·
49chevysd said:
Ive taken that thing in and out so many times. Ive never had that much trouble seating a converter!!! Any other possible reasons than I just havent got it seated correctly?? thanks..
you do not have to take it out! just turn the converter with your hand while pushing it to the pump! from what you wrote i cannot tell if you have the converter bolted to the flex plate now? if you do? you have to unbolt it push it back and then align your bell housing to the block/bolt it up then pull the converter up to the flex plate and bolt it up! if you did this already there must be and interference issue somewhere??
 
#8 ·
350

The simple way to know if the converter is in far enough is to try to fit your fingers behind the converter. If you can fit your fingers between the converter and the pump, it is not seated. If your fingers will not fit, it should be in.

If you tried to force the engine and trans together with the bell housing bolts, you may have damaged the pump.

Rick
 
#9 ·
actually the old housing was cracked. I had a transmission shop here swap the internal components into a fresh case. The shop who primarily builds race transmissions said everything was tip-top. but ill try the "finger test," i havent tried that yet. good idea...
 
#12 ·
well i tried to fit the converter into the tranny this morning and i noticed something strange. looking down the front pump into the tranny, it doesnt look like the keys are directly across from each other. Is it possible for them to somehow come out of alignment? On the converter of course the keyholes are directly across from each other, but it doesnt look that way inside the transmission. thanks for any help!!
 
#13 ·
350

Those two tabs are part of the oil pump inner gear, and this is all one piece. If they aren't directly opposite each other, the gear must be broke. I am a little confused on the cracked case, did this happen trying to force the engine and trans together? If so the pump gear is probably also broken. If you are unsure about the pump you should take the trans to a shop and have them inspect it. They shouldn't charge you anything if it is OK and doesn't need to be taken apart. If the gear is broke, make sure they inspect the whole pump or put in a rebuilt pump.

Good luck,
Rick
 
#14 ·
Ricky Rocket said:
Those two tabs are part of the oil pump inner gear, and this is all one piece. If they aren't directly opposite each other, the gear must be broke. I am a little confused on the cracked case, did this happen trying to force the engine and trans together? If so the pump gear is probably also broken. If you are unsure about the pump you should take the trans to a shop and have them inspect it. They shouldn't charge you anything if it is OK and doesn't need to be taken apart. If the gear is broke, make sure they inspect the whole pump or put in a rebuilt pump.

Good luck,
Rick
you can insert a small pick and try to rotate or move the tangs to see if it is still in one piece
 
#16 ·
update.

well, i took it to a shop here on a saturday (why is it they all have to be closed on the weekends?) and he couldnt give me a straight answer, other than the splines looked a little chewed up. I am actually taking the th350 and the converter to a shop tomorrow to get it inspected. I have also run into another problem with my motor mounts not fitting so I got sort of side tracked. Ill post once I get an answer on the tranny.

-49chevysd
 
#17 · (Edited)
TH350 Idea

OK I hate to admit what I am about to tell you should never go beyond the internet :nono: So, I had this Pontiac overhead cam 6 cyl. I built a TH and was trying to bolt it up. I had the VERY same problem as you are having. :confused: I thought, "oh... I must not have the converter engaged all the way..." then upon try, after try, I realized that, yep!, it IS engaged all the way. Anyway, I built a spacer plate out of Aluminum.. (a great piece of craftsmanship, i might add) and bolted this thing together. :smash: It worked great until it took out the front pump. As it turned out, the gear pump impeller (the one that engages the torque converter hub) was installed backwards. That's why it would go all but the last three quarters of an inch:mad: Put a new pump in... tranny bolted up perfect without my spacer plate. :cool: You may also be trying to put a non locking converter onto a locking imput shaft. good luck.
 
#18 ·
that could very well be similar to what i am experiencing. out of my frustration i finally took it to a tranny shop and am having the front pump replaced. Upon inspection, they told me that the splines were chewed up (obviously i noticed that on my own) but they also told me that there was an unusual wear on the pump gear. And after looking at the convert and th350 both they told me a new front pump would solve the problem. Im supposed to get it back tomorrow, so we shall see. thanks for all the great advice guys!!

-49chevysd
 
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