'69 Small Block Ignition Shielding

[Mark P.]

I am trying to install the ignition shielding on the driver side. When I bought the '69 it had no ignition shields at all. Now I had the exhaust manifold off and installed a new gasket because the old one was leaking. So I thought it is a good idea to install the chrome radio shields I bought some time ago... (before they get old stock). I had already installed the heat shields earlier.
I did expect that the shielding can be removed by unbolting the wing screws and leaving the brackets in place (bolted on with the exhaust manifold bolts). Somehow this does not work for the front shielding (the one with the hole for the temp sensor). The inner heat shield and the outer radio shield cling together and I can not remove the radio shield without unbolting the manifold bolts.
I looked in the AIM for inpiration and in the drawing for the radio shields, there is no inner heat shield for the front driver side. Did cars with radio have no inner shield or was it ommitted in the drawing only? Or is there a trick I have missed?

[Joe L.]

Re: '69 Small Block Ignition Shielding

Mark----

The left front position originally DID use BOTH the spark plug heat shield and the RF shield. The servicing "phenomenon" that you describe which is associated with this set-up is quite common; I've been dealing with it for 33 years on my original owner, 1969 small block (I'll soon be "temporarily" rid of the problem when I install the "ZL-1"). It will take a lot of "playing around with it" and slightly readjusting the heat shield and the RF shield brackets, but it can be done. When you finally get it right, you'll likely have numerous cuts, scrapes, and scratches on your hands and arms.

By the way, small block exhaust manifolds NEVER originally used gaskets between the manifold and the cylinder head. The only reason that these are ever required in SERVICE is if your manifolds become warped. This can be checked with a precision straight edge. If necessary, having the manifolds surfaced by a machine shop will correct the problem and is far preferable to installing gaskets.

[Mark P.]

Is this how it should look like?

I am not sure if this is correct with the heat shield coming out of the radio shield. In this position the shields were only little stubborn to get in.
Hope this pic shows up...

[Terry M.]

Re: Is this how it should look like?

Mark,

The heat shield should be inside the chrome ignition shield. Your photo has it backwards.

[Jeffrey S.]

Re: '69 Small Block Ignition Shielding

Mark:
I also have struggled with this piece of shielding and have found that leaving the wing nuts tight and removing the exhaust manifold bolts and removing the shield and the brackets together, the piece comes away very easily. I also have to remove one of the steering box cover bolts so the manifold bolt can be withdrawn.
Hope this helps
Jeff

[Mark P.]

Re: Is this how it should look like?

I expected this. All the other heat shields are inside and it was too easy to do this way....

[Joe L.]

Re: Is this how it should look like?

Mark------

Well, they say that a picture is worth a thousand words and so is the case here. The shield that you have installed is GM #3919807. That is also the shield shown in the AIM engine assembly section. However, bear in mind that the configuration shown in the AIM is the configuration in the "standard car" (NO options) condition. When one of the radio options was selected (which include RF shielding), then this heat shield was NOT used.

That leaves two options: either no shield was used or another shield was used. In the case of my original owner, mid-September, 1969 built car, another shield was used. That shield was a GM #3917664, the same shield used for the right rear position. It's still a struggle to get this heat shield to fit under the RF shield, but it can be done; I've been doing it for 34+ years now. I consider it impossible for the 3919807 to fit under the shield. I tried one once to see if it would be easier than my original shield. The use of the 3917664 shield in conjunction with the RF shield does make for very close contact between the heat shield and the temp sender. You have to be sure that the electrical connector is well insulated as the originals were.

Incidentally, I believe that this rather poorly designed "system" was the reason that 1968-71 Corvettes originally used the pin terminal temp sending units. Prior to 1968, the only Corvette that was ever fitted with a pin terminal unit was the 1956. If the button terminal unit used for 57-67 and 72+ had been used in this set-up, it would have added "another layer of complexity" to the whole thing. So, the reversion to the pin terminal helped solve the problem. The pin terminal wasn't really necessary after 1969 (or, possibly, early 1970) since the front RF shields for radio installations were deleted then. However, apparently, it took GM awhile to respond to this change with respect to the temp sender. For 1972 they did, though, and it was back to the button terminal.

The set-up that I described with the heat shield and RF shield as on my car CAN be done with the button terminal, though. I've been doing it for years, too, since I replaced my original sender years ago. Not for a want of a properly operating temp sender, though; my original was perfect. It was for want of a serviceable pin style connector/insulator assembly.

By the way, the GM #3917664 shield is still available from GM.

[Mark P.]

Are these the parts that should fit in here?

The inner shield does not fit into the outer shield, not even outside the car. I could make it fit with a little bending. But before I go back to the garage I would like to know if I have the correct parts....

[Mark P.]

Pic with inner shield in place *NM*

[Mark P.]

other Pic with inner shield in place *NM*

[Mark P.]

This explains my problems. Thanks a lot! *NM*