So I went to install the heat shields between the exhaust manifold and the spark plugs today...
3 of the four went on.
The last one, right-rear, I could not put on, because the hole for the mounting screw appears to have never been drilled, or covered over, or something.

Here is a picture of it. the flat part that the arrow points to is where the hole should be. This is a GM crate motor.
Anyone ever seen anything like this?


Click it for a really big version.

Adam its something very simple that when the original corvette blocks came down the line they drilled and taped this hole for heat shielding, but with the crate engine it has more of a general purpose and there for the machining process is general nothing specific for any one car.
where as original cars had a more precise machining.
When the general built these motors they may have just skiped drilling that hole.
I would drill it out and tap it but be very carefull and only drill as deep or even less than the other heat shielding bolt holes.

then tap it with a starting tap smoth tapered starting threads and finish it with the bottoming tap and you should be just fine.
if you dont drill it as deep as the original make the bolt a little shorter and you will be ok..

johnny

When I first looked at the blown-up picture, I could bet I saw a slotted machine screw with JB weld spread around it. Are you sure there is no tapped hole there that was covered up for some reason??