ID'ing 2 polished(?), finned Buick valve covers

[Deanoko]

These came off my LT code 401 and are headed over to my KW code 425

One is 1377933 with oil fill, plug and dimple.

The other is 1366222 with the central pcv.

 

My questions:

Did these start life as a matched set, or are they a pair of orphans?

What is the dimple for?

I'm planning on the oil fill on the left and the pcv on the right.  Correct, or just "OK"?

Engine builder put the rocker oil splash pan between #3 and 5 on the right.  Is that to guard the pcv from splashing?

  '64 Car is factory AC. 

Many thanks! 

[drwatson]

Here they are for sale on eBay. The description in the ebay ad seems to answer your questions.

https://www.ebay.com/itm/254926801059

 

Edited January 25, 2023 by drwatson (see edit history)

[Deanoko]

Re: questions - Well, sort of.  There's no clearance issue no matter which side they're mounted on, so the dimple remains a mystery. 

What would the sequential part number be for the 1366222#?  I read here that xxx23 is not a good number.

I am surmising that they started life far apart.  Good thing is they look like a pair 

[drwatson]

22 hours ago, Deanoko said:

so the dimple remains a mystery. 

I mentioned the description on the ebay ad, It describes "the dimple" .

I see now there is a p/n issue. Both of your p/n's appear on GM parts wiki but only give history of obsolescence, not make, model.

Here's text from the ebay ad:

"This is a set of original Buick Cast Aluminums valve covers part #s 1377932 and 1377933 that were removed for an airconditioned car. This set includes the original a/c compressor bracket and one of the covers has a dimple to allow clearance.  They will fit any nailhead Buick engine form 1953 thru 1966. Finding original covers is becoming vey difficult. Please do not confuse these with the reproductions as the show judge will know the difference. "

 

Edited January 26, 2023 by drwatson (see edit history)

[Deanoko]

Yes, I got that.  The dimple must come into play on some application, but not an issue on my loaded '64.  It's going to be forward on the driver's side.  The nearest thing to it is the power steering pump, which is not a conflict. 

[jframe]

The dimple was there on 1966  ONLY covers to allow for clearance of a smog pump that was expected to be installed beginning that year.

[TooManyCars]

Here are some low quality pics of the valve covers on my 65 Electra for reference. One has a dimple, the other does not. 

Edited February 24, 2023 by TooManyCars (see edit history)

[Deanoko]

The only logic I see to the dimple is when it is on the right rear where it would give the tranny dipstick a bit of clearance. On the left front there's nothing to interfere.