Bolts

[Morris R.]

Does anyone know the correct bolts that should be used in bolting a muncie m20 transmission to the bellhousing and the bolts used to bolt the bellhousing to the motor? (327/350hp) i have 6 bolts marked "m" on the heads for the transmission to the bellhousing i'm not sure if that is right and not sure with the ones i have for the bellhousing (4) to the motor, the headmarks are "le" can someone please clear this up? Thank you

[Joe L.]

Re: Bolts

Does anyone know the correct bolts that should be used in bolting a muncie m20 transmission to the bellhousing and the bolts used to bolt the bellhousing to the motor? (327/350hp) i have 6 bolts marked "m" on the heads for the transmission to the bellhousing i'm not sure if that is right and not sure with the ones i have for the bellhousing (4) to the motor, the headmarks are "le" can someone please clear this up? Thank you

Morris-----


The bellhousing-to-block bolts were flanged head, 3/8-16 X 1-1/4", zinc plated with untrimmed ("indented") head and GM 280-M material (3 radial ines). I believe "M" was a common headmarking as were "A" and "C".

The transmission-to-bellhousing bolts were 1/2-13 X 1-3/4", zinc plated with trimmed ("non-indented") head and of GM-280M material. I think that "TR" was a common headmarking as were "A" and "P".

[Morris R.]

Re: Bolts

Joe did you ever see "le" bolts? Could they be correct for the transmission to bellhousing? Thank you for replying

[Joe L.]

Re: Bolts

Joe did you ever see "le" bolts? Could they be correct for the transmission to bellhousing? Thank you for replying

Morris-----

Vaguely, I seem to recall seeing "LE" headmarked bolts as common hardware store bolts. However, I suppose it's possible that such headmarked bolts were originally used. If the bolts you have show any evidence of chromate overplate (i.e. "gold" coloring), then they are definitely not original.

[Gary B.]

Re: Bolts

Does anyone know the correct bolts that should be used in bolting a muncie m20 transmission to the bellhousing and the bolts used to bolt the bellhousing to the motor? (327/350hp)

Morris,

Attached are notes and a sketch of those original bolts from my '66 L79.

Gary
Bolts.jpg

[John H.]

Re: Bolts

Joe did you ever see "le" bolts? Could they be correct for the transmission to bellhousing? Thank you for replying

Maury -

"LE" headmarked bolts were made by the Lake Erie Screw Company, but I don't recall ever seeing that headmark on transmission bolts. There are (4) transmission-to-bellhousing bolts, and (6) bellhousing-to-block bolts.

[Morris R.]

Re: Bolts

Thank you everyone big help

[Mark E.]

Re: Bolts

Morris,

Attached are notes and a sketch of those original bolts from my '66 L79.

Gary
[ATTACH=CONFIG]43408[/ATTACH]

Are the 4 bolts attaching the Muncie case to the bell housing really zinc plated with no grade marking?

What grade are these bolts?

Same bolts for small block and big block?

My 1970 454 has 3 black phosphate grade 8 bolts (with two different markings) and 1 grade 5 zinc bolt, so I want to sort this out.

[Gary B.]

[David B.]

Re: Bolts

If you would provide a part number for these bolts a lot of your question could probably be answered correctly. The '71 4 speed bolts are listed as
# 100161 if the same as '70 these are plain 1/2-13 x 1 3/4 grade GM 260-M.

[Patrick H.]

Re: Bolts

10 years later you resurrect this?

[Gary B.]

IMG_4067.jpg

[Mark E.]

Re: Bolts

[ATTACH=CONFIG]117233[/ATTACH]

Thank you Gary!

Now to find a source for these. I'm surprised these are not grade 5 or 8 bolts. CC sells grade 5 with different head markings for this application.

AIM lists PN 100161. Is there a reference that provides the specs given the PN?

[Mark E.]

Re: Bolts

10 years later you resurrect this?

Yes, I researched my question and found this thread addressing the same question. To avoid a new thread on the same topic I posted here.

Would a new thread with a link here be preferred?

[Mark E.]

Re: Bolts

Thank you Gary!

Now to find a source for these. I'm surprised these are not grade 5 or 8 bolts. CC sells grade 5 with different head markings for this application.

AIM lists PN 100161. Is there a reference that provides the specs given the PN?

I found this thread on CF answering my question.

https://www.corvetteforum.com/forums/c3-tech-performance/2936488-how-do-i-find-bolt-fastener-size-from-aim-or-shop-manual.html