L78 Questions

[James W.]

I have some questions related to L78's that I'd like to get answered.

1. In the 1965 AIM there is a diagram view A on UPC6, B1 showing the starter. It appears that they are calling for some sealer to be placed in the gap between the engine/clutch splash shield and the starter. This is not in the L78 specific section of the AIM.

My question is should this or would this have been done on all cars no matter which engine was installed? Also the JG says nothing about this sealer.

2. The '65 JG references that the bellhousing/clutch inspection cover is attached with four recessed hex-head bolts located on the bottom foward face. I've heard that the attaching hardware for the inspection cover should be pan-head slotted screws.

Which is correct? I am building the car to what the JG states but I would like to know what has been judged correct. This is again on a L78 engine.


3. Again the '65 JG references that the bellhousing/clutch inspection cover as being in place when the engine was being painted. The JG make no mention of the initial manufacturer's color of the inspection cover but states that it is painted engine color (orange) although degree of coverage may vary. In the mechanical section of the JG under engine color, paint, and mounts it states that on manual transmission equipped cars the bellhousing and attaching bolts will have overspray from the engine painting process. The degree of coverage may vary from slight to near total. I would assume this would include inspection cover. I've been told that this inspection cover was originally black in color. The replacememnt inspection cover that I purchased was also black in color. When I painted the engine I painted the inspection cover to the point that is almost completely orange.

My questions are;

Is/was the inspection cover black when new?

Will I get docked points if there is no black color showing?


Any help would be greatly appreciated.

Thanks and Happy New Year.


James West

[Jim D.]

Re: L78 Questions

The inspection cover on my 65 is held in place by the recessed head bolts and the unpainted portions of it are bare steel. It is original and had never been removed until I did it. No traces of black anywhere on it.

Also, I wouldn't build my car according to the JG. It has several mistakes.

[Wayne M.]

Re: L78 Questions

James -- Agree with Jim D.; inspection covers were bare before being painted orange -- ie. facing flywheel it should be bare steel (service covers are painted totally black).

But this brings up another point. Tonawanda painted engines, ie L78, have the bellhousing (almost ?) completely painted orange, as opposed to the Flint engines with their limited overspray on the attaching bolts.

[Joe L.]

Re: L78 Questions

I have some questions related to L78's that I'd like to get answered.

1. In the 1965 AIM there is a diagram view A on UPC6, B1 showing the starter. It appears that they are calling for some sealer to be placed in the gap between the engine/clutch splash shield and the starter. This is not in the L78 specific section of the AIM.

My question is should this or would this have been done on all cars no matter which engine was installed? Also the JG says nothing about this sealer.

2. The '65 JG references that the bellhousing/clutch inspection cover is attached with four recessed hex-head bolts located on the bottom foward face. I've heard that the attaching hardware for the inspection cover should be pan-head slotted screws.

Which is correct? I am building the car to what the JG states but I would like to know what has been judged correct. This is again on a L78 engine.


3. Again the '65 JG references that the bellhousing/clutch inspection cover as being in place when the engine was being painted. The JG make no mention of the initial manufacturer's color of the inspection cover but states that it is painted engine color (orange) although degree of coverage may vary. In the mechanical section of the JG under engine color, paint, and mounts it states that on manual transmission equipped cars the bellhousing and attaching bolts will have overspray from the engine painting process. The degree of coverage may vary from slight to near total. I would assume this would include inspection cover. I've been told that this inspection cover was originally black in color. The replacememnt inspection cover that I purchased was also black in color. When I painted the engine I painted the inspection cover to the point that is almost completely orange.

My questions are;

Is/was the inspection cover black when new?

Will I get docked points if there is no black color showing?


Any help would be greatly appreciated.

Thanks and Happy New Year.


James West

James------


The flywheel covers used in PRODUCTION were bare steel prior to painting with the engine assembly. Most SERVICE covers are painted black. So, if you can see black paint on any flywheel cover (except ZL-1), you know that it's a SERVICE cover

[James W.]

Re: L78 Questions

Thanks for the replys guys. I painted the inspection cover so that there is no black showing since it is in fact a service replacement. The car had a Lakewood scatter shield in place when the car was bought. I'm still looking for more input from L78 owners but I appreciate the replies.

I did think of one more question. Is there a difference in length for the lower clutch rod (big block vs. small block) that goes between the clutch lever assembly and the clutch fork?

Thanks,

James West

[John H.]

Re: L78 Questions

I did think of one more question. Is there a difference in length for the lower clutch rod (big block vs. small block) that goes between the clutch lever assembly and the clutch fork?

Thanks,

James West

James -

My notes show that the '65 BB used #3872960 lower (fork) pushrod (8-9/16" long), and SB's used #3844209 (10-9/16" long). The upper (pedal) pushrod for BB's was #3872961 (19-1/4" long), and SB's used #3819154 (18" long). The cross-shaft (Z-bar) was also different between BB and SB.

[Carl N.]

Re: L78 Questions

James,

You ask for input from owners of L78 optioned '65s - having owned one since 1970 - IMO all answers provided are correct and accurate.

I cannot add anything to what has been stated except concur -----

Good luck with your restoration!

Carl

[Wayne M.]

Re: L78 Questions

L78 test for pics --- might delete if can't get this to work. OK, I'm going to fly with this. Ignore the two pics of clutch inspection covers; I'll try and get them to the correct thread. I can't delete them (or one of them) to post a 3rd pic of upper clutch rods.

Point is that 396 upper rod was unique 3872961.

[Joe L.]

Re: L78 Questions

L78 test for pics --- might delete if can't get this to work. OK, I'm going to fly with this. Ignore the two pics of clutch inspection covers; I'll try and get them to the correct thread. I can't delete them (or one of them) to post a 3rd pic of upper clutch rods.

Point is that 396 upper rod was unique 3872961.

Wayne-----


Off the subject of this thread but note the color of the original shield. Note how much more red it has in it than the shield you (or someone) painted with "Chevrolet orange". I don't think this has anything to do with deterioration, either. This is EXACTLY the color I recall from original engines in the mid 60's to very early 70's. Most of the "Chevrolet orange" paints available today have too little red and too much orange. This includes the paint available from GM for the last 40 years.

[Wayne M.]

Re: L78 Questions

Wayne-----


Off the subject of this thread but note the color of the original shield. Note how much more red it has in it than the shield you (or someone) painted with "Chevrolet orange". I don't think this has anything to do with deterioration, either. This is EXACTLY the color I recall from original engines in the mid 60's to very early 70's. Most of the "Chevrolet orange" paints available today have too little red and too much orange. This includes the paint available from GM for the last 40 years.

Joe -- I agree; [turns out I was in the correct thread after all]. The top shield in both pics appears to be original; the bottom pic is service (the blue/white sticker on the black back reads 3788422. Got each one at a different year at Carlisle.

But there's one other feature I'd like to point out to all; these do not have those two "clips" (ears ?) at the crank area, which I also believe indicates a more recent service part. I think they hook into the rear main cap, or something.

P.S. One more difference; the original has a straight edge, the service has the outboard 3 or 4" bent forward (I think this feature abuts against the flat bottom face of the engine block. I wonder if they kept the same part # throughout these minor changes ?

[Joe L.]

Re: L78 Questions

Joe -- I agree; [turns out I was in the correct thread after all]. The top shield in both pics appears to be original; the bottom pic is service (the blue/white sticker on the black back reads 3788422. Got each one at a different year at Carlisle. But there's one other feature I'd like to point out to all; these do not have those two "clips" (ears ?) at the crank area, which I also believe indicates a more recent service part. I think they hook into the rear main cap, or something. P.S. One more difference; the original has a straight edge, the service has the outboard 3 or 4" bent forward (I think this feature abuts against the flat bottom face of the engine block. I wonder if they kept the same part # throughout these minor changes ?

Wayne----- The original cover for 1963-72 applications using 12-3/4" flywheels was the GM #3788422 which you have pictured. There were revisions over time to the 3788422 such as you have described. The two integral clips you described were added to the 3788422 sometime toward the end of its manufacture but I don't think the clip versions were ever used in PRODUCTION. In January, 1976 the 3788422 was discontinued from SERVICE and replaced by the GM #354497. It is this cover that has the clips, too. The cover for 1966-74 14" flywheel applications is GM #3843943. This cover was used in PRODUCTION throughout the period and is available in SERVICE to this day. It was revised over the years, too, and among the revisions was the addition of the clips without a change in part number. As far as I know, all of the PRODUCTION pieces had no clips but it is possible that these were added in 73 or 74. The revision to add the clips happened prior to or about 1975. 1975-81 with 14" flywheel used a different cover of GM #340252. By the way, the clips are designed to fit behind the rear oil pan seal lip and thus prevent inward deflection of the cover. When this occurs usually caused by driving through deep puddles of water or road debris strikes, the cover comes in contact with crankshaft flange and causes an alarming racket. Would I seek out or use a cover without the clips for benefit the nuance of originality? NEVER, EVER!

[Joe L.]

Re: L78 Questions

Attached are photos of the GM #3843943, 340252, and 354497 flywheel covers. Note that the difference between the 66-74 GM #3843943 and the 75-81 GM #340252 is the location and configuration of the integral clips. Why, since the 1967-74 14" bellhousings were the same? Well, it's got nothing to do with the bellhousings. In 1975 the Corvette small block oil pan changed. So, the revised clips were in order to accommodate the new oil pan with slightly revised rear oil pan flange. By the way, the SERVICE oil pans for 1963-74 Corvette small blocks after about 1975 used the slightly revised pan flange, too (don't confuse the slight rear flange change with the front seal change for 1975+ and 63-74 SERVICE pans). So, the 340252 is actually the correct cover for 1963-74 with a 75+ SERVICE oil pan. Nobody told you that, though. No matter, however, as the 340252 is GM-discontinued.DSCN2575.jpgDSCN2576.jpgDSCN2577.jpg

[Joe L.]

Re: L78 Questions

More photosDSCN2574.jpgDSCN2578.jpg

[Joe L.]

Re: L78 Questions

Also, I can discern absolutely no difference between a GM #3788422 version which has the clips and the GM #354497. There must be a difference but I sure can't tell what it is.

[Tony S.]

Re: L78 Questions

James -- Agree with Jim D.; inspection covers were bare before being painted orange -- ie. facing flywheel it should be bare steel (service covers are painted totally black).

But this brings up another point. Tonawanda painted engines, ie L78, have the bellhousing (almost ?) completely painted orange, as opposed to the Flint engines with their limited overspray on the attaching bolts.

Hi Wayne. Happy New Year.

Is your opinion that the small block production inspection covers were also natural rather than semi gloss black?

As for the orange paint on the inspection cover, would you expect that it would not be fully painted orange?

Best,
Tony