1965 396 timing cover tab

[Dave C.]

I am trying to validate the timing tab on my 1965 396 motor. I have the center bolt hole etc. Does the 1965 and 1966 BB have the same tab.

thanks

Dave

[Joe L.]

Re: 1965 396 timing cover tab

Dave-----

Yes.

[Dave C.]

Re: 1965 396 timing cover tab

thanks Joe - I was hoping you were out there somewhere. I am finally getting close to putting the engine back together. I am still waiting for the galley plugs you gave me the gm part numbers on.

[Michael H.]

Re: 1965 396 timing cover tab

Wonder what the difference is between 65 and 66. I thought they were the same but the part number was different for 65. They both used the front center bolt. I wonder if the 66 part included the new longer timing tab that included the "R" for retard since that was the first year for Calif emissions and a retarded setting on some engines. (not 425 HP BB)

Original number for 65 was 3860068, replaced by the 66 design, 3885054.

[Joe L.]

Re: 1965 396 timing cover tab

Michael-----

I believe that the change in timing cover part numbers occured sometime after the beginning of the 1966 model year. I do not know how these two differed.

[Michael H.]

Re: 1965 396 timing cover tab

Hopefully, someone has one of each handy so we can learn the difference. As I mentioned, the front center bolt would have been on both 65 and 66. Also, both would lack dowel pin holes as that didn't begin until 67 if I remember correctly.

The 3885054 would most likely have been used from SOP for the 66 model year as the part number falls right in line with the majority of new to 66 engine components for the year.

[Joe L.]

Re: 1965 396 timing cover tab

Michael-----

The center bolt was used only for 65-66. However, the dowel pins did not begin until 1969. However, I would not rule out the possibility that earlier timing covers had the holes. The presence of the holes would in no way interfere with the functionality of the timing cover for use on non-dowel pin applications. So, the dowel pin hole covers did not, necessarily, have to enter production coincident with the dowel pin blocks.

I agree that the part number for the 3885054 cover would seem to be consistent with use at the start of production for 1966. However, I think that you're trying to make too much of an "exact science" out of the this sequential part numbering thing. I've used it, myself, for years but I've learned that it's not an "exact science", at all. It's just a "rule of thumb" or "rough guide". There are all kinds of reasons that the release of parts to PRODUCTION and/or SERVICE might vary from "strict adherence" to sequential number. In this case, I think that the cover changed sometime after the start of 1966 PRODUCTION.

It's going to be very difficult to verify one cover from the other unless someone has one of each in the GM box. These covers bear no part number, so there is no way to identify one from another. Of course, it might be possible to observe some difference in covers, but that would be hard to attribute to a particular part number.

[Michael H.]

Re: 1965 396 timing cover tab

Can you tell me why you think it entered production after SOP 66?

I doubt a 3885054 cover would ever have dowel pin holes if they didn't appear until 69 on the block. I believe the part number for the cover changed again before 1969.

[Joe L.]

Re: 1965 396 timing cover tab

Yes, I'll tell you why. The initial printing of the 1966 model year P&A Catalog, dated 10-1-65, shows the GM #3860068 as being applicable to 1966 passenger and Corvette with SHP 427, "FIRST DESIGN". The GM #3885054 is shown in the same catalog as being applicable to 1966 passenger and Corvette with SHP 427, "SECOND DESIGN". The next edition of the catalog shows the same thing.

By the final edition of the catalog for the 1966 model year, the GM #3860068 had disappeared and just the 3885054 was shown for all 1966 passenger and Corvette SHP 427 applications. That's because the GM #3860068 cover was discontinued in May, 1966 and replaced by the GM #3885054.

[Michael H.]

Re: 1965 396 timing cover tab

Sounds like proof to me. I'll make a notation in my mid 66 printing of the parts book. Now all that's left is the physical difference in parts and I think I know how to find that info. I know of an NOS 3885054 in the box. I'll try to get info.

[Bill W.]

65 timing tab

The 65 BB tab from 16120 is 1&1/16" long & has 11 degree marks on it. the only 66 I have is a low horse & it is 2&1/8 long and has 17 degree marks...Bill

[Michael H.]

Re: 65 timing tab

Thanks Bill. Does it have the "R" on the lower portion in addition to the ")" and "A"? Is this part on an engine?

[Bill W.]

Re: Who establishes the production date for a 56

The 66 part has an r the 65 does not..yes I have the complete 65 engine & some of the 66....Bill

[Bill W.]

Re: 65 timing tab

John Wagner ..why does my responses keep going back to this 56 info????it says subject 65 timming tab! It also keeps asking my user name..Bill

[Joe L.]

Re: 1965 396 timing cover tab

Dave-----

OK, I think that I've got this thing figured out now. I researched this matter a long time ago but lost my notes (until now) and forgot exactly what the deal was. I think this is it:

1965 L-78 and early 1966 L-72 used timing cover GM #3860068. This cover has a "squarish" timing tab which is "flat". The tab is ABOUT 1-3/8" long. It may or may not have the letters "AO" on it. I'm not sure about this. The cover also has a completely symetrical "wagon wheel" with "4 spokes". It has a center weld nut at the center of the bottom radius and NO dowel pin holes;

L1966-68 L-72 and L-71 used timing cover GM #3885048. This timing cover is exactly the same as the above except that it has a longer, more "rectangular" timing tab with an angled upper, inner corner and is ABOUT 2-1/4" long. It has 17 degree marks. It may or may not have the letters "AOR"; I'm not 100% sure about this feature. The timing tab is "flat".