66 327 inspection cover bolts

[Brian K.]

Okay the judging manual says 7/16 recessed hex head bolts, but some of the venders sell the slotted screw type for 1966. My clutch had been changed so not sure if mine are correct (hex head) and the judging guide has been wrong so I just want to clarify what's correct.

[Joe L.]

Re: 66 327 inspection cover bolts

Okay the judging manual says 7/16 recessed hex head bolts, but some of the venders sell the slotted screw type for 1966. My clutch had been changed so not sure if mine are correct (hex head) and the judging guide has been wrong so I just want to clarify what's correct.

Brian------


Hex head.

[Brian K.]

Re: 66 327 inspection cover bolts

Thanks again JOE for the reassurance, I can sleep peacefully tonight.

[Ralph E.]

Re: 66 327 inspection cover bolts

Please excuse this tag to this post.
Can the inspection cover be removed with the oil filter in place.
The small bolt near the canister or screw-on filter seems very tight. Can it be removed?

[Larry M.]

Re: 66 327 inspection cover bolts

So this thread is about two years old but I have the same question. The 63/64 Judging guide says recessed hex with E or L. Most vendors say pan head for 63-66 and hex for 67 but always hex for powerglide...they likely learned that from somewhere. Joe says hex for 66 above but I wonder if we have given this proper attention.

[Gary B.]

Re: 66 327 inspection cover bolts

Brian,

The original inspection cover bolts on my July build date '66 are indented hex head with a captured external tooth washer and with either L head-mark or a wavy flag head-mark.

Gary

[Joe L.]

Re: 66 327 inspection cover bolts

Brian,

The original inspection cover bolts on my July build date '66 are indented hex head with a captured external tooth washer and with either L head-mark or a wavy flag head-mark.

Gary

Gary------


GM #3817006. By the way, this part number dates back to 1962. That, of course, does not mean it was used since then for the oil pan and timing cover applications. However, it does mean that it was available for use for those applications since that time.

[Larry M.]

Re: 66 327 inspection cover bolts

A July 66 car might be a lot like a 67 on this. This would have been an engine plant change and not a St. Louis change. The part number to 62 would be necessary to support powerglides. Hopefully some others like Alan Drake will weigh in.

[Gary B.]

Re: 66 327 inspection cover bolts

Gary------


GM #3817006. By the way, this part number dates back to 1962. That, of course, does not mean it was used since then for the oil pan and timing cover applications. However, it does mean that it was available for use for those applications since that time.

Joe,

Is GM 3817006 documented to have a captured external tooth washer?

Gary

[Joe L.]

Re: 66 327 inspection cover bolts

The part number to 62 would be necessary to support powerglides.

Larry------


Not necessarily. There are many other bolt/washer configurations that could have been used for Powerglides.

[Joe L.]

Re: 66 327 inspection cover bolts

Joe,

Is GM 3817006 documented to have a captured external tooth washer?

Gary

Gary-------


Yes. The GM #3817006 is the exact configuration seen on oil pans and timing cover bolts and also other applications like water pump backing plates, etc.).

When it was discontinued from SERVICE more than 20 years ago, it was replaced by separate bolt and washer. The bolt was a trimmed ("non-indented") head of GM #180016 and external tooth lock washer of GM #121753.

[Richard G.]

Re: 66 327 inspection cover bolts

Here are some pictures;
Having done many transmissions these bolts are typical for 60 gm stuff not only the Corvette.

[Joe L.]

Re: 66 327 inspection cover bolts

Here are some pictures;
Having done many transmissions these bolts are typical for 60 gm stuff not only the Corvette.

Richard------


If this bolt is from prior to about 1962, then it must be some predecessor part number to the GM #3817006. The 3817006 couldn't have existed prior to about 1962. I also note that it appears that this bolt is black phosphate-finished. If so, that could imply it's of a different and possibly earlier part number since I believe the 3817006 was always a zinc plated part.

Actually, I've always wondered why the 3817006 was zinc plated. Virtually all of the applications I know of for these bolts had them painted after installation (e.g. timing cover, flywheel cover, oil pan). Usually, GM would not specify any plated finish for fasteners to be subsequently painted. I suppose the purpose was economy since fasteners to be painted did not really need to be first plated. However, it may be that there were enough non-painted applications for the bolt that they may have decided plating was in order.

[Richard G.]

Re: 66 327 inspection cover bolts

Joe;
The 1/4 bolt in the picture should be a Dec 62 bolt.
Thanks for sharing your knowledge on fasteners.
Many of the nuances of the larger items are fairly well known.
The fastener details are still being dug up!
Thank you.
Rick

[Marco H.]

Re: 66 327 inspection cover bolts

Gents,
There have been plenty of original - unrestored small block cars observed with slotted screws and external star washer to secure the clutch cover. From '63 through beginning '66. I have not seen an unrestored 396/427 with slotted screws yet.

Marco