Bellhousing bolts?

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April 11th, 2011, 05:49 AM

defiant1

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Bellhousing bolts?

I cannot find the damn bellhousing bolts from when I removed the motor. Anyone know what size and length these bad boys are? (TH350/350 motor)

Thanks

d1

April 11th, 2011, 05:58 AM

TripDeuces

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3/8 x 18 x 1.5?

April 11th, 2011, 06:08 AM

defiant1

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Quote:

Originally Posted by TripDeuces

3/8 x 18 x 1.5?

3/8 x 16, correct? is there a 18 thread pitch? 1.5" sounds right.

April 11th, 2011, 06:10 AM

TripDeuces

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Yeah 16 not 18, You can just measure the flange thicknesses and add the two together for the length. Just make sure they engage fully

Last edited by TripDeuces; April 11th, 2011 at 06:12 AM.

April 11th, 2011, 06:29 AM

Bluevista

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Oldsmobile parts catalog - 3/8"-16 x 1-3/8".

April 11th, 2011, 06:32 AM

defiant1

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Quote:

Originally Posted by TripDeuces

Yeah 16 not 18, You can just measure the flange thicknesses and add the two together for the length. Just make sure they engage fully

Quote:

Originally Posted by Bluevista

Oldsmobile parts catalog - 3/8"-16 x 1-3/8".

Thanks gentlemen. Off to the parts store I go.

November 13th, 2023, 11:58 AM

wozny442

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Different lengths, what goes where?

Sorry, I know this is an old thread but I thought I’d try. Putting my TH350 back in and noticed that two of the original bolts are a little longer, wondering what positions the longer ones reside in.

November 14th, 2023, 06:00 AM

oddball

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I think only one hole is a blind hole - the others are open on the backside, so it doesn't actually matter.
Having a specific length is more about being able to get a socket/wrench onto the bolt!

November 14th, 2023, 06:33 AM

Sugar Bear

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Check the depth of a blind hole before putting a bolt in, the bolt should not bottom out in the hole. A bottomed out bolt will not provide clamping force and can cause major damage to components.

November 14th, 2023, 09:47 AM

#10

olds 307 and 403

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The longer two would be up top, one captures the trans dipstick eyelet. I upgraded to grade 8 bolts, 1.25 and 1.5" 3/8-16 is what I used with lock washers.