Help ID this timing Chain Cover

[Joe L.]

Re: Help ID this timing Chain Cover

Joe,

I agree with most of your list but this is what I have found:

62-63 w/F.I., S.H.P.----GM # 3817174

64-65 W/F.I., S.H.P.----GM # 3851549

66-67 w/S.H.P. ---------GM # 3885048

68 w/S.H.P. ------------GM # 3923290
GM # 3923290 is listed in my 1968 Chev. Parts Catalog (Oct. 1967) only for the 68 Corvette 327 w/S.H.P.

From Chev. Parts History (service parts sold over the counter):
3817174 ----- replaced in Jan. 1964 by 3851549 ----- replaced in May 1966 by 3885048 ----- replaced in Jan. 1968 by 3923290 ----- replaced in 1977+/- by 361925 (disc. April 1985).

Enclosed is a page from one of my note books. I believe that the tab on the 66-67 and 68 timing covers for the 8" balancer probably use the large tab.

Dave

Dave-----

Yes, I missed the 3923290 for 1968. Also, the GM #361925 is a SERVICE-only cover that has dual timing tabs for both 6 and 8 inch balancers. One of the tabs is to be removed depending upon which balancer is installed.

[David L.]

Re: Help ID this timing Chain Cover

Joe,

Pictured below is a 1968 timing cover for a 7" balancer stamped "68" but no number stamped for the week of the year. I suspect that the 1968 timing cover for the 8" balancer is similar.

Dave

[Michael H.]

Re: Help ID this timing Chain Cover

Someone must have a photo of a 1966-1967 timing cover w/8" balancer to verify my assumptions.



Dave

No input on this one? Anyone? Doesn't anyone have a 66-67 350 HP in the garage they can get info from?

Maybe all the 66-67 small blocks have been converted to big blocks.

[John H.]

Re: Help ID this timing Chain Cover

No input on this one? Anyone? Doesn't anyone have a 66-67 350 HP in the garage they can get info from?

Maybe all the 66-67 small blocks have been converted to big blocks.

Michael -

Sorry, my ultra-rare '67 big-block-delete car is a 300hp.

[Michael H.]

Re: Help ID this timing Chain Cover

Michael -

Sorry, my ultra-rare '67 big-block-delete car is a 300hp.

You, sir, have a very rare car.

[Bob J.]

Re: Help ID this timing Chain Cover

Michael,
Don't know the part number, since bugs ate the sticker, but the cover came out of Smokey's and the box was inked 327.
Its stamped 34 69 upside down above the crank seal which I guess to be 34th week /day 1969.
Bob

[Michael H.]

Re: Help ID this timing Chain Cover

Michael,
Don't know the part number, since bugs ate the sticker, but the cover came out of Smokey's and the box was inked 327.
Its stamped 34 69 upside down above the crank seal which I guess to be 34th week /day 1969.
Bob

[David L.]

Re: Help ID this timing Chain Cover

Timing cover # 3923290 was used in production only on 1968 models. I believe that the timing cover stamped "34 69" (34th week on 1969) in Bob's photo is a service cover, GM # 3923290 for the following reasons:

1. The "0" degree mark appears to be at 45 degrees just like my original 1966 timing cover (for 6" balancer, GM # 3885039) as shown in my photos posted Oct. 4th @ 9:41 PM.

2. The 1966-1967 timing cover for 8" balancers, GM # 3885048, was discontinued in January 1968 and replaced by GM # 3923290, the 1968 timing cover, which also was used as a replacement timing cover for 1962-1967 models. GM # 3923290 was sold over the counter from January 1968 to 1977+/-. The 34th week of 1969 is in this time frame.

3. The 1969-1970 timing cover for 8" balancers has a different style of tab and the zero degree mark is NOT located at 45 degrees. I have an original 1969-1970 timing cover for 8" balancers stamped "33 69" (33rd week of 1969). My 1969-1970 cover is just like the one in the photo below.

Dave

[Michael H.]

Re: Help ID this timing Chain Cover

Timing cover # 3923290 was used in production only on 1968 models.

Dave

I wonder what the difference is between the 66-67 8" cover and the 68 8" cover?

We still don't have a pic of a 66-67 cover for 8" balancer.

Maybe I'll start a new thread looking for pictures/info on the 66-67 cover/timing tab.

I'll leave 68 and 69 and all that are not for 8" out for now as this is already confusing enough.

It would be nice to see pictures/info for all of the 8 inch 63-67 timing tabs in one thread.

[Joe L.]

Re: Help ID this timing Chain Cover

Timing cover # 3923290 was used in production only on 1968 models. I believe that the timing cover stamped "34 69" (34th week on 1969) in Bob's photo is a service cover, GM # 3923290 for the following reasons:

1. The "0" degree mark appears to be at 45 degrees just like my original 1966 timing cover (for 6" balancer, GM # 3885039) as shown in my photos posted Oct. 4th @ 9:41 PM.

2. The 1966-1967 timing cover for 8" balancers, GM # 3885048, was discontinued in January 1968 and replaced by GM # 3923290, the 1968 timing cover, which also was used as a replacement timing cover for 1962-1967 models. GM # 3923290 was sold over the counter from January 1968 to 1977+/-. The 34th week of 1969 is in this time frame.

3. The 1969-1970 timing cover for 8" balancers has a different style of tab and the zero degree mark is NOT located at 45 degrees. I have an original 1969-1970 timing cover for 8" balancers stamped "33 69" (33rd week of 1969). My 1969-1970 cover is just like the one in the photo below.

Dave

David-----

All 1969 and later small blocks had the timing mark position revised. That's the reason that the 1968 and earlier timing covers and balancers are all different than the 1969 and later timing covers and balancers. Of course, the actual timing cover is interchangeable for all Gen I small blocks but the timing tab and its location is different.

[Wayne M.]

Re: Help ID this timing Chain Cover

All 1969 and later small blocks had the timing mark position revised. That's the reason that the 1968 and earlier timing covers and balancers are all different than the 1969 and later timing covers and balancers. Of course, the actual timing cover is interchangeable for all Gen I small blocks but the timing tab and its location is different.

Here's a pic of the Chev Service News, Sept-Oct '68, that shows the marked difference between '68 and '69 Chev small block timing covers. The texts says "The front end cover is new due to the relocation of the timing degree scale. Visibility was obscured by the new arrangement of the accessory drive components". 2nd pic is a close-up of the tab. I've heard that this tab was not used on '69 Corvettes ? true or not ? Is the degree scale shifted upward by 9 or 10 degrees ?

Going back a year, it seems that '68 was different than '66-7, and the text in the 1968 New Product manual says: "The 307, 327 and 350 cu.in. engines have a new cover with a relocated timing tab to standardize and accommodate the new torsional damper. Anybody care to give details ?

In both paragraphs above, no mention made whether these cover versions apply to 8" or to the smaller dia. balancers.

[Joe L.]

Re: Help ID this timing Chain Cover

Here's a pic of the Chev Service News, Sept-Oct '68, that shows the marked difference between '68 and '69 Chev small block timing covers. The texts says "The front end cover is new due to the relocation of the timing degree scale. Visibility was obscured by the new arrangement of the accessory drive components". 2nd pic is a close-up of the tab. I've heard that this tab was not used on '69 Corvettes ? true or not ? Is the degree scale shifted upward by 9 or 10 degrees ?

Going back a year, it seems that '68 was different than '66-7, and the text in the 1968 New Product manual says: "The 307, 327 and 350 cu.in. engines have a new cover with a relocated timing tab to standardize and accommodate the new torsional damper. Anybody care to give details ?

In both paragraphs above, no mention made whether these cover versions apply to 8" or to the smaller dia. balancers.

Wayne-----


The original timing tab on my 1969 is as pictured. All 1969-71 Corvette small blocks used an 8" balancer. Thickness did vary from base engine to L-46/LT-1. However, ALL Chevrolet small blocks beginning with 1969 and regardless of OD of balancer used the revised timing mark and timing tab location.

1968 Corvettes with base engine did use a unique-to-1968 balancer, GM #3914684. How it differed from earlier balancers I do not know. However, the 1968 L-79 used the same GM #3817173 part number as earlier.

[Wayne M.]

Re: Help ID this timing Chain Cover

.... Also, the GM #361925 is a SERVICE-only cover that has dual timing tabs for both 6 and 8 inch balancers. One of the tabs is to be removed depending upon which balancer is installed.

Hey Joe -- here's a 2-tab that just ended on eBay. Part tag seems to read part #3928971. seller claims NOT for 8" balancers. (huh ?) The space between the degree markings is wider on the outboard tab.

[Joe L.]

Re: Help ID this timing Chain Cover

Hey Joe -- here's a 2-tab that just ended on eBay. Part tag seems to read part #3928971. seller claims NOT for 8" balancers. (huh ?) The space between the degree markings is wider on the outboard tab.

Wayne-----


I missed this SERVICE-only cover. GM #3928971 replaced the earlier "single tab" covers for SERVICE in October, 1973 although the part number appears to be about 1968-released. The GM #3928971 was discontinued in September, 1977 and replaced by the GM #361926. The latter is the "dual tab" cover I am familiar with. I think the difference is that the 3928971 is the "tri-spoke" style whereas the 361976 is the "dished" style. The 361976 was discontinued without supercession in April, 1994.