Left Rear Side Ignition Shield

[Alger R.]

I am currently assembling my 75 L48 4 spd engine and am having a problem with the Lt Rr Side Ignition Shield interfering with the Clutch Cross Shaft Stud. I have the two retainer tabs properly positioned on the exhaust manifold. When I wing nut the shield on to the retainers the bottom directly interferes with the stud. I can lift the shield over the top but it sits tight against the stud and the cross shaft is not yet in place? I tried to maneuver the shield to decrease the interference but to no avail. I notice that an older shield for a 68-72 has a scallop recess in the bottom to clear the stud. My shield does not have the scallop recess but is supposed to be correct for 73 on up. Doesn't seem to fit...Help!

[Joe L.]

Re: Left Rear Side Ignition Shield

I am currently assembling my 75 L48 4 spd engine and am having a problem with the Lt Rr Side Ignition Shield interfering with the Clutch Cross Shaft Stud. I have the two retainer tabs properly positioned on the exhaust manifold. When I wing nut the shield on to the retainers the bottom directly interferes with the stud. I can lift the shield over the top but it sits tight against the stud and the cross shaft is not yet in place? I tried to maneuver the shield to decrease the interference but to no avail. I notice that an older shield for a 68-72 has a scallop recess in the bottom to clear the stud. My shield does not have the scallop recess but is supposed to be correct for 73 on up. Doesn't seem to fit...Help!

Alger-----

The same, basic left rear shield was used for many years. I don't think that interference problems are unique to any of the years it was used since the positional relationship between the shield and the cross shaft was the same for all years.

At some point during it's period of use, the "cutout" was added although the part number did not change. In my opinion, the cutout did nothing to eliminate the interference problem. I can tell you that the left rear shield on my original owner 1969 small block had been "factory modified" by bending on the bottom to provide clearance. I have seen other of these shields similarly modified. However, I have also seen some that were not modified. I do not understand how these ever worked without interference.

[Alger R.]

Re: Left Rear Side Ignition Shield

I have attached pics of two different shields. One with scallop, one without. The scalloped version fits better but I am not sure if that design carried thru 1975. Also both shields fit terribly at the top rear with interference with the french lock. If you squeeze them enough, they both fit? Unless I am installing them wrong, I cannot imagine anyone designing those parts to fit like that. I was a designer at Fisher Body and that would never have past.

[Joe L.]

Re: Left Rear Side Ignition Shield

I have attached pics of two different shields. One with scallop, one without. The scalloped version fits better but I am not sure if that design carried thru 1975. Also both shields fit terribly at the top rear with interference with the french lock. If you squeeze them enough, they both fit? Unless I am installing them wrong, I cannot imagine anyone designing those parts to fit like that. I was a designer at Fisher Body and that would never have past.

Alger-----


The GM #3923969 shield was used for 1968 through 1979. I don't know when the "cutout" was added, though. As I mentioned, with or without the cutout interference with the cross shaft will occur.

My 1969 shield did not have the cutout. However, it had been "bent inward" on the lower, middle portion of the shield to provide clearance.

Yes, the design of this shield was very poor and it was never really corrected even though the shield was used for 11 years.

[Terry M.]

Re: Left Rear Side Ignition Shield

I am pretty sure my 1970 (Jan 29, and not all that far from your 1969, Joe) has the cut out. I can easily look if you have some interest. Even if it does, I would be reluctant to use such flimsy results as proof of "it starter here."

[Alger R.]

Re: Left Rear Side Ignition Shield

The information I have had (absolutely unsubstantiated) is that the shield with the cutout scallop was used from 68 to 72. They then removed the scallop and ran it thru 79. It really didn't make sense to remove the scallop unless it was an extra stamping operation? It makes more sense that the scallop was added because of the poor clearance? I have one of each for my 75 and don't want to use the wrong one for judging.

[Terry M.]

Re: Left Rear Side Ignition Shield

The scalop might have been removed as you suggest -- to cut costs -- as the number of manual transmission Corvettes decresed.

[Joe L.]

Re: Left Rear Side Ignition Shield

I have attached pics of two different shields. One with scallop, one without. The scalloped version fits better but I am not sure if that design carried thru 1975. Also both shields fit terribly at the top rear with interference with the french lock. If you squeeze them enough, they both fit? Unless I am installing them wrong, I cannot imagine anyone designing those parts to fit like that. I was a designer at Fisher Body and that would never have past.

Alger-----

I was incorrect regarding my 1969 not having the "cut-out". For some reason, I was thinking in terms of a much larger cut-out and didn't recall this one. It's definitely there, though. However, the cut-out on mine appears to have been rather crudely accomplished. It does not look to me like this was die cut. It may have been done by the manufacturer or at St. Louis as a "last-minute" modification. Also note the "bashed in" area that provides extra clearance. This was the way mine came and I noted it the first time I removed it for a spark plug change. I think this was done at St. Louis "to make it fit".

If it actually occurred, I absolutely do not understand why the relief and cut-out was later removed. WITH the relief and cut-out the shield will interfere with the cross-shaft. WITHOUT the relief and cut-out, there's no chance, at all, that the shield will clear the cross shaft. So, if anything, the relief and cut-out should have been made larger. As I previously mentioned, there would have been absolutely no change in the relationship of the shield to the cross shaft throughout the 68-81 period so it's not like some other later change eliminated the need for the relief and cut-out.

[Alger R.]

Re: Left Rear Side Ignition Shield

Joe, Thanks for the response. To give you some background, I am bench assembling my engine before dropping on the chassis. In setting the angle of the two small Ignition shield brackets I temporarily put on the left shield. I couldn't believe it when the lower edge of the shield directly hit the clutch stud right in the middle. What I have since done is literally bend the entire lower flange up to gain the clearance. I have not yet checked how the cross shaft will fit or I may have to bend it even further??

Your right...The fix should have been to make that conical cutout even larger rather than eliminate it???