68 Big Block left side Valve Cover Grommet

[Rich G.]

Once again, the search is on. I bought a few from the Doc several years ago but although he shows them on his site there is no add to cart button for that item which I guess means he doesn’t have any.

Paragon has some that that require simple cutting of the end that goes into the valve cover. Once that is done per their instructions it looks exactly like the old ones......but it isn’t. The inside diameter is ok and the elbow goes in if you do that before you try to put it in the valve cover. Once it’s on the elbow it will not go into the cover. It will go into the cover without the elbow in it but then the elbow won’t go into it.

Using lubricants and a hair dryer did not help. I finally gave up and got a set of calipers. The outside diameter of the part that sits in the hole in the valve cover is too big, significantly bigger than the old one. So when pushed into the cover first the inside diameter becomes too small to accept the elbow. When the elbow is installed first the rubber can’t flex enough to get in the hole.

The Paragon part is 1259. The Doctor number is 3856954. But I’m pretty sure he is out of stock on these.

Anybody got another source?

Thanks

Rich

[Donald S.]

Re: 68 Big Block left side Valve Cover Grommet

There has got to be others (like myself) that have the same issue as Rich. I ended up cutting the whole bottom off but it won't stay in the valve cover. I thought of trying other catalog companies other than Corvette that have parts for big block chevy motors but hate throwing my money away.


Don

[Joe L.]

Re: 68 Big Block left side Valve Cover Grommet

Once again, the search is on. I bought a few from the Doc several years ago but although he shows them on his site there is no add to cart button for that item which I guess means he doesn’t have any.

Paragon has some that that require simple cutting of the end that goes into the valve cover. Once that is done per their instructions it looks exactly like the old ones......but it isn’t. The inside diameter is ok and the elbow goes in if you do that before you try to put it in the valve cover. Once it’s on the elbow it will not go into the cover. It will go into the cover without the elbow in it but then the elbow won’t go into it.

Using lubricants and a hair dryer did not help. I finally gave up and got a set of calipers. The outside diameter of the part that sits in the hole in the valve cover is too big, significantly bigger than the old one. So when pushed into the cover first the inside diameter becomes too small to accept the elbow. When the elbow is installed first the rubber can’t flex enough to get in the hole.

The Paragon part is 1259. The Doctor number is 3856954. But I’m pretty sure he is out of stock on these.

Anybody got another source?

Thanks

Rich

Rich------


Yes, there is another source------GM.

The original left side cover grommet (for the vent elbow connector) used in PRODUCTION and once available in SERVICE was GM #3933188. The latter was discontinued from SERVICE in December, 1971 and replaced by GM #3989346 which was then discontinued from SERVICE in February, 1972 and replaced by GM #3894337. The latter remains available from GM to this day. GM says that the 3894337 has an ID of 15/16" and an OD of 1-7/32".

The original right side grommet (for the PCV valve) used in PRODUCTION and once available in SERVICE was GM #3933189. The latter was discontinued from SERVICE in December, 1971 and replaced by GM #3989347 which is still available from GM to this very day.

However, I would presume that Paragon and the other vendors obtain their grommets from GM but I suppose it's possible they use some other source.

As an aside, something I have never understood is why the 3894337 grommet out-of-the-box has the integral "cap" on the bottom which, presumably, must be removed or, at least, altered in some way prior to installation. I just don't understand what application would ever have required this. Incidentally, this part number dates back to about 1967 and actually pre-dated the release of the 3933188 and 3989346.

[Joe L.]

Re: 68 Big Block left side Valve Cover Grommet

There has got to be others (like myself) that have the same issue as Rich. I ended up cutting the whole bottom off but it won't stay in the valve cover. I thought of trying other catalog companies other than Corvette that have parts for big block chevy motors but hate throwing my money away.


Don

Don------


While you may have found it necessary to remove it, if the lower retaining lip of the grommet is removed, there's no way in the world that the grommet will be retained in the valve cover.

[Joe L.]

Re: 68 Big Block left side Valve Cover Grommet

Rich and Don------


By the way, are you both sure that your valve covers AND elbow connector are original GM pieces and not some bogus, off-spec reproductions? One of the reasons I ask that is because the elbow connector in Don's photo appears to be black painted. Originals were phosphate or black oxide finished. Also, the valve covers look to be show chrome, not the original type flash chrome.

[Rich G.]

[Rich G.]

[Rich G.]

Re: 68 Big Block left side Valve Cover Grommet

Here is a picture of the Paragon grommet next to one I got from Doc Rebuild years ago. It looks like the one I got from Doc had been trimmed by them before shipping. At the time he said he only had three left and couldn’t get more. Perhaps these were the GM ones and the Paragon ones are repros that are slightly off. Who knows?
The one on the right is from Paragon and has not been trimmed yet.

Rich

[Joe L.]

Re: 68 Big Block left side Valve Cover Grommet

Here is a picture of the Paragon grommet next to one I got from Doc Rebuild years ago. It looks like the one I got from Doc had been trimmed by them before shipping. At the time he said he only had three left and couldn’t get more. Perhaps these were the GM ones and the Paragon ones are repros that are slightly off. Who knows?
The one on the right is from Paragon and has not been trimmed yer

Rich

Rich------


Those do not appear exactly the same to me. The lower retaining lip configuration is different. The Doc's might be of the earlier part number 3933188 or, even, 3856954. Those would be extremely difficult to locate having been discontinued almost 50 years ago.

[Mark G.]

Re: 68 Big Block left side Valve Cover Grommet

This may not be the cheapest alternative, but, what about buying a used cover with the grommet or is this the correct size? https://www.ebay.com/itm/OER-K0083-V...wAAOSwRFldCavz

[Rich G.]

Re: 68 Big Block left side Valve Cover Grommet

EDIT EDIT

I should have read closer. The dimensions are there but they are not correct for 68 and 69 BB. This mistake is common in that vendors think one size fits all, but that left side grommet is unique to 68 and 69.

The ones on eBay are for the right side, I think. Without dimensions it’s hard to tell. The one on the right looks like the right shape but my dim memory tells me I made that mistake in the past.

Rich

[Joe L.]

Re: 68 Big Block left side Valve Cover Grommet

Well, this situation intrigued me enough that I did some more checking and measuring.

The diameter of the grommet orifice in the known GM big block valve cover that I measured is 1.179".

The OD of the GM #3894337 grommet at the surface that interfaces with the valve cover orifice is 1.211". So, already we have a potential problem but some compressibility of the grommet can be expected.

However, the OD of the grommet at the surface which with interfaces with the valve cover orifice and with the GM #3868842 connector (elbow) installed is 1.277". There is no way that a diameter of 1.277" is going to work in a 1.179" orifice even considering some compressibility of the grommet. In order to accomplish this, either the valve cover will be distorted or the grommet will break.

The uncompressed inside diameter of the GM #3894337 grommet is 0.939"

The GM #3894337 grommet and GM #3868842 I used for this test were very old stock so this problem has been with us for a very long while. I do not know if the problem was created by a difference in the specs between the original GM #3933188 and/or GM #3989346 and the current (since February, 1972) part number of GM #3894337 OR if the problem occurred sometime during the long life of the GM #3894337.

[Mark G.]

Re: 68 Big Block left side Valve Cover Grommet

If you haven't scrolled further down, it lists the dimensions.

[Joe L.]

Re: 68 Big Block left side Valve Cover Grommet

If you haven't scrolled further down, it lists the dimensions.

Mark------

If those are the actual and precise dimensions of the grommets, I think it would make the situation worse.

[Rich G.]