3843943 bell housing inspection cover, need advice from Joe Lucia

[Patrick B.]

While troubleshooting an intermittent but very ugly sound coming from my newly restored 1967 427, I concluded that the crankshaft was making very slight contact with the inspection cover whenever the crankshaft was as far forward as the rear thrust bearing would allow. (Only a few thousandths but influenced by pressure on the throw out bearing). My parts book listed 3843943 as the inspection cover for both big blocks and small blocks with 11 inch clutches, and pictures of this part showed tangs that would engage the rear edge of the oil pan and prevent the cover from contacting the crankshaft.

Further examination of my car revealed that its inspection cover did not have any tangs to engage the oil pan and keep it away from the crankshaft. It seems that part 3843943 was changed from its 1967 configuration without a change in part number. I can see that 3843943 would fit both big blocks and small blocks in the configuration without tangs. But the rear of the oil pan has a much larger opening for a big block, and the tangs on the inspection cover cannot fit both big blocks and small blocks. Is the Service version of 3843943 made to fit a small block or a big block? What would be the part number of the other version of the 11 inch inspection cover? I can only find the one part number but it cannot be right for both big blocks and small blocks unless you have to flatten out the tangs and forego their utility for one family of engines.

[Joe L.]

Re: 3843943 bell housing inspection cover, need advice from Joe Lucia

While troubleshooting an intermittent but very ugly sound coming from my newly restored 1967 427, I concluded that the crankshaft was making very slight contact with the inspection cover whenever the crankshaft was as far forward as the rear thrust bearing would allow. (Only a few thousandths but influenced by pressure on the throw out bearing). My parts book listed 3843943 as the inspection cover for both big blocks and small blocks with 11 inch clutches, and pictures of this part showed tangs that would engage the rear edge of the oil pan and prevent the cover from contacting the crankshaft.

Further examination of my car revealed that its inspection cover did not have any tangs to engage the oil pan and keep it away from the crankshaft. It seems that part 3843943 was changed from its 1967 configuration without a change in part number. I can see that 3843943 would fit both big blocks and small blocks in the configuration without tangs. But the rear of the oil pan has a much larger opening for a big block, and the tangs on the inspection cover cannot fit both big blocks and small blocks. Is the Service version of 3843943 made to fit a small block or a big block? What would be the part number of the other version of the 11 inch inspection cover? I can only find the one part number but it cannot be right for both big blocks and small blocks unless you have to flatten out the tangs and forego their utility for one family of engines.

Patrick-----

As you found, the original version of the GM #3843943 did not have the clips for engagement with the oil pan rear flange. These were added without a change in part number at some point but I don't know exactly when. I do know that 1970 and prior did not have them. Sometime after that they were added.

The clips will work for both small block and big block. However, for big block applications they are bent back somewhat. They will still function as intended, though.

Here's proof-positive:

DSCN3675.jpg

[Patrick B.]

[Joe L.]

Re: 3843943 bell housing inspection cover, need advice from Joe Lucia

Joe——-Thanks for the information. I ordered 2 of them and intend to use one of them on a 1970 small block. I managed to pry my old one slightly away from the crank and got rid of the disturbing noise. I am trying to understand your photo. That does not look like an oil pan with the stud and 12 point nut.

Patrick------


The stud and 12 point nut is not stock and/or original. It's an ARP item. I use only one piece oil pan gaskets which are thicker than stock 4 piece. So, stock oil pan bolts are not long enough. Of course, I could have obtained bolts that were a lot closer to stock configuration but longer than originals. But, I'm not trying to fool anyone. I prefer ARP fasteners as "non-original" as they might be. So, the stud and nut pictured is the right side rear oil pan to block fastener.

By the way, as far as originality goes, the covers with the clips, for both 12-3/4 and 14 flywheel bellhousings, were never originally used for any pre-1971 Corvette (and, likely for quite a few years after that). Theoretically, these would be discernible in judging of such year models. However, I would NEVER, EVER use a non-clip (i.e. original configuration) cover. NEVER, EVER.

[Patrick B.]