The original rear engine cover plates were designed to Accomodate the STOCK Muffler. ALL other aftermarket rear engine cover plates maintained the original shape. The problem is, when using a Merged Header type Exhaust,or a tight fitting Sidewinder A-1 Header Exhaust, the cover plates on the market today don't fit very well.
When trying to connect the Fresh Air Tubes, the 1.3/8" - 1.5" or the 1.7/8" header pipes cover a portion of the cut out holes and the Fresh Air Tubes get crushed, touching the HOT Header Pipes.
Other times, you have to grind, cut, etc the cover plates just to make them fit and the header pipes are touching the cover plates and transferring the heat from the header pipes into the engine compartment.
It is almost unbelievable, we have fought these cover plates for over 50 years.
Please take a look at our modified cover plates, available in Fiberglass paint grade or painted and sheet metal cover plates, Chromed available for heater or no heater.

We installed a Stock Chromed Breast Plate and a Stock Chromed Cover Plate to an Engine Case. The distance from the Engine case to the inner wall of the cover plate measured 3" inches.

Our NEW modified Fiberglass Cover Plate Fits very close to the Crankshaft Pulley, creating all this extra space for the Exhaust Header Pipes. It SUBSTANTIALLY reduces the heat transfer from the header pipes into the engine compartment.

With our modified Rear Engine Cover Plates we locate and cut the fresh air tube holes, so the Fresh Air Tubes are amply spaced away from the HOT Header Pipes.