1974 L48 Left Side Ignition shield

[Robert S.]

My 74' L48 was missing all of the spark plug heatshields and the two horizontal chrome ignition shields. I purchased replacements for all and all were installed with no problems or issues other than the left side horizontal chrome plated ignition shield.
The ignition shield, which was received in perfect condition, cannot be installed in any orientation that would even come close to allowing the two wing screws to be installed. ALthough the part is not marked (it is package marked) it appears to exactly match the picture of the part on the sellers website so I do not think I got the wrong part sent to me. Their website says the part is good for 73' to 79'. I checked two other vendors who list their own part number for this shield to cover 73' to 79' so it would not appear that my sellers catalogue is wrong on the application range. I called the seller to see if they had had any quality vendor issues and the call revealed nothing. The car has stock exhaust manifolds and is otherwise in factory condition and very pristine and all the other parts when on with no issues which suggests a stock configuration.
When I look in the 74' AIM, the cartoon of the part looks more like the shield this sellers sells for a 68' to 72' but I do not know if that means anything as I assume the AIM cartoons are not always updated when the part shapes change.
I am at a loss as to what to do next. I can return the part and order from someone else but I might wind up with the same part sold to me by another company.

So has anyone else had this experience with this left side shield? If someone could post a picture of this shield either off or on the car it would help me decide where to go next. Is it possible I should be using the shield that is sold for a 68' to 72'?

[William C.]

Re: 1974 L48 Left Side Ignition shield

According to the '75 parts book, same drivers side shield 73-75, looks a lot like the earlier shields. any possibility you have the incorrect supports? 3817759 towards the front an 3819759 to the rear.

[Joe L.]

Re: 1974 L48 Left Side Ignition shield

My 74' L48 was missing all of the spark plug heatshields and the two horizontal chrome ignition shields. I purchased replacements for all and all were installed with no problems or issues other than the left side horizontal chrome plated ignition shield.
The ignition shield, which was received in perfect condition, cannot be installed in any orientation that would even come close to allowing the two wing screws to be installed. ALthough the part is not marked (it is package marked) it appears to exactly match the picture of the part on the sellers website so I do not think I got the wrong part sent to me. Their website says the part is good for 73' to 79'. I checked two other vendors who list their own part number for this shield to cover 73' to 79' so it would not appear that my sellers catalogue is wrong on the application range. I called the seller to see if they had had any quality vendor issues and the call revealed nothing. The car has stock exhaust manifolds and is otherwise in factory condition and very pristine and all the other parts when on with no issues which suggests a stock configuration.
When I look in the 74' AIM, the cartoon of the part looks more like the shield this sellers sells for a 68' to 72' but I do not know if that means anything as I assume the AIM cartoons are not always updated when the part shapes change.
I am at a loss as to what to do next. I can return the part and order from someone else but I might wind up with the same part sold to me by another company.

So has anyone else had this experience with this left side shield? If someone could post a picture of this shield either off or on the car it would help me decide where to go next. Is it possible I should be using the shield that is sold for a 68' to 72'?

Robert-----


The left side rear RF shield was the same for all 1968-79 Corvettes, although I do think it was slightly revised in configuration in the later C3 period. Regardless, the shield should work for all 68-79 applications. It was GM #3923969.

I agree with Bill; I think you've got the support brackets wrong.

[Robert S.]

Re: 1974 L48 Left Side Ignition shield

I bought the sellers bracket set of 4 and used two on the right side, one straight and one bent and everything went on with no issues.
I installed the remaining two on the left side with the straight one on the rear bolt and the bent one on the front bolt - this seemed logical given the cutouts in the shield which would only allow the bent one to come in from the forward side at an angle.

Is this the correct location of the brackets? The AIM pictures do not help and the vendor part numbers are not the GM part numbers.

[Harmon C.]

Re: 1974 L48 Left Side Ignition shield

The shields are not easy to install with the engine on a stand. I would position the shield and then try to attach the brackets to the shield and test to see if the angle is correct before installing them on the manifold bolts. It you do this with both bolts out of the manifold and the brackets you have won't line up I would say you have the wrong brackets or the other side is not on the correct way. One side uses a third wing bolt is it lined up?

[Robert S.]

Re: 1974 L48 Left Side Ignition shield

The right side shield fits perfectly and all three wing bolts were used, two on top and the one below which mates with the vertical shield.

[Jack H.]

Re: 1974 L48 Left Side Ignition shield

There's a reason prior owners/mechanics discarded the radio RF shields and I think you're discovering why they did this!

The factory put the shielding on with the engine OUT of the engine compartment giving them reasonable access to work with the parts. With the engine installed, there's a LOT less room to work with and things can appear 'impossible' to align until you've learned the secret(s)....

On the lower, horizontal shields it's often the case that the parts will NOT align for their fasteners to install and there's a trick that the 'rate buster' mechanics use to get the job done.

The lower shields install with wing nuts penetrating the shield's support brackets (L-shaped). The mistake commonly made by novice mechanics is to install the support brackets first, then try to get the shields to align for the wing nut installation. WRONG!

Install the support brackets, but DO NOT torque them down firmly. Leave enough freedom in the support bracket mounting bolts so you can 'swing' the brackets from side to side and still have them hold their position.

Now, test fit the shield using the wing nuts and move the support brackets as required until the brackets align with the holes in the shield and the wing nuts will 'bite' thread.

Remove the shield and, while holding each support bracket in its 'preferred' position, do the final torque on the bracket's attaching bolt.

NOW, come back with the shield and run the wing nuts home. If you're even a tiny bit off with the proper geometry of the support brackets and their final installed postion, you'll fight and curse the poor/sloppy fit of the shields whose wing nuts refuse to align!!!!

[Joe L.]

Re: 1974 L48 Left Side Ignition shield

The right side shield fits perfectly and all three wing bolts were used, two on top and the one below which mates with the vertical shield.

Robert-----


One other thought: is interference of the lower portion of the shield with the clutch cross shaft causing any of your fitment problem?

[Robert S.]

Re: 1974 L48 Left Side Ignition shield

The shield appears to want to interfer with the clutch cross shaft on the bottom (no cutout for the shaft), wants to interfer with the small cable bracket on the firewall and the fingers on the shield top do not to seem to want to fit above the spark plug heatshields and last but not least none of the slots in the shield top seem to want to line up with the the dipstick tube. Hence my original question which suggests I have the wrong part.
I described how I mounted the brackets - can anyone comment if I did correctly?

[Joe L.]

Re: 1974 L48 Left Side Ignition shield

The shield appears to want to interfer with the clutch cross shaft on the bottom (no cutout for the shaft), wants to interfer with the small cable bracket on the firewall and the fingers on the shield top do not to seem to want to fit above the spark plug heatshields and last but not least none of the slots in the shield top seem to want to line up with the the dipstick tube. Hence my original question which suggests I have the wrong part.
I described how I mounted the brackets - can anyone comment if I did correctly?

Robert----

Earlier examples of the 3923969 shield DO interfere with the clutch cross shaft. On my original owner 1969, the shield had been "bent" on the bottom to cause it to clear the cross shaft. This had to have been done at St. Louis because I never did it. I believe that the shield was modified in later years to provide relief for the cross-shaft. I never had any problem with the other issues you described.

It's hard to imagine you have the wrong shield. The 3923969 was the only shield even remotely configured that way. The 1966-67 left rear shield was "open" at the rear rather than "closed" like the 3923969. Plus, the 66-67 or, even, the 64-65 shield should fit just fine, anyway. The later 1980-82 shield was of a completely different configuration and did not use the manifold bolt-mounted supports. It attached with a lower bolt(s).

[Robert S.]

Re: 1974 L48 Left Side Ignition shield

The seller also sells a shield that is listed for application for 68 - 72. This shield looks more like the cartoon in the AIM, and appears to have a cutout for the cross shaft but the seller says the one I have should fit. A rear mystery.
I guess unless someone posts a picture of a shield sinstalled on a 74' I will have to find a 74' with a shield installed and see if it looks like the part I have.

[Robert S.]

Re: 1974 L48 Left Side Ignition shield

Issue resolved. I finally derermined the part would not fit until the french lock was bent over at mid span. I used small vicegrips, a drift and a hammer to bend the lock at midspan over against the exhaust manifold. Once done that allowed the lower right tang of the shield to move into place and the shield wing bolts to be installed.
Thanks to all who responded. I entered this post to hopefully help others in the future who are fitting these commonly missing parts.