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Old 02-27-2025, 07:40 PM   #1
Kalums
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Transmission issues

Ok here is a random one and hopefully someone has experienced this or understands... Ok finally dropped my "K" block 350 in my 1971 GMC and.... For some reason my flexplate and torque converter are about 3/4-1" apart... I can scoot the torque converter forward towards the engine but then it isn't connected to the pump... Also when I install my starter, the flexplate is ON the opening for the bendix. Not like I need shims, but like up against the opening, again not up against the teeth(top or bottom of the starter) but against the flat edge(side) of the flexplate teeth. The flexplate is far enough away from the torque converter it makes me VERY wary of putting shims in. Local trans shop said 1) I may have the wrong flexplate (even though it is a pioneer 168T with an external "batwing" weight, "for one piece seals") or 2) I may need the LS "crank spacer".
BTW it is a TH350 with an NP205

Have any of you guys had similar experiences? Thoughts? Ideas? I want to get this sucker up running again... But man this one is too much for my limited knowledge.

Last edited by Kalums; 02-27-2025 at 08:33 PM. Reason: Clarification
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Old 02-27-2025, 08:27 PM   #2
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Re: Transmission issues

Check that the converter spins freely. You might have stacked it when installing the engine. Ask me how I know this.
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Old 02-27-2025, 08:32 PM   #3
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Re: Transmission issues

Quote:
Originally Posted by Steeveedee View Post
Check that the converter spins freely. You might have stacked it when installing the engine. Ask me how I know this.
It does spin freely, but it I have it in (like it is supposed to be, by my understanding) I can hear the fluid pumping /moving inside. If I pull it "out" to hook it up to the flexplate it spins easier and I don't hear the fluid movement.
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Old Yesterday, 11:49 AM   #4
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Re: Transmission issues

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Originally Posted by Kalums View Post
It does spin freely, but it I have it in (like it is supposed to be, by my understanding) I can hear the fluid pumping /moving inside. If I pull it "out" to hook it up to the flexplate it spins easier and I don't hear the fluid movement.
That's above my paygrade. Maybe someone with more transmission experience will chime in.
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Old Yesterday, 12:06 PM   #5
70STOVEBOLT
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Re: Transmission issues

When you say "K" block, are you referring to the engine plant code or 4-wheel drive? If the engine is a 1970's vintage engine, you have the wrong flex plate, as those engines use a 2-piece rear main seal.
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Old Yesterday, 12:24 PM   #6
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Re: Transmission issues

Disregard, I see in your engine swap-arino thread that it is a 1993 engine.
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70 C/10 SWB 402/TH400/3.73 "The Needy Beast"
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Owner installed options:
Front Sway Bar
Power Steering
Power Brakes
Cigar Lighter
Courtesy Lights
Deluxe Side Markers
Wiper Delay
Sliding Rear Window
Power Windows
Power Locks
Sniper EFI

2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear
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Old Today, 02:20 AM   #7
Kalums
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Re: Transmission issues

So... New development, took all the bolts out again..... And low and behold there was a kick down cable squashed between the bell housing and block, right in front of the transmission dipstick. *facepalm* So apparently even if your 4 bottom bolts are "flat" they many not actually be flush. Pulled that out (need a new one), bolted all 6 bolts up this time and bam, gap is down to 0.512 of an inch... 1/2" is way more "shimable" than double that space. The local transmission shop I called the other day is probably going to get this TH350 soon any way, it seems to now be leaking from every possible orifice, apparently didn't like being bonked around... *sighs*... Leaking from the Pan seal near the front passenger side, from the dipstick mating "hole", definitely from the rear seal/output shaft, the governer... there is even a smidge of pink film behind the torque converter... Thank you to everyone who contributed.
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