1983 Porsche 911 SC Targa

Saturday, November 15, 2014


Removing the engine leaves behind some vestigial elements. The first is cosmetic, but the opening under the left side of the bumper for the exhaust pipe really bothered me.
I made a foam core fiberglass plug to fill the void. I reinforced the mounting location with a strip of plywood inset with t-nuts. The epoxy resin used to lay-up the fiberglass soaks into plywood and protects it from water and rot.

After primer, lots of sanding, factory match paint and clear coat, the new plug is mounted on the frame I built for mounting the radiator.

The rear deck grill is vented for dumping engine waste heat and cooling the air conditioner condenser. The air conditioner was already removed before I got the car, and water and electricity don’t mix, so I need to seal that vent up. My first attempt to make a fiberglass tray failed miserably. I tried to make separate fiberglass parts using the deck lid opening and grill as molds. I lined the car parts with plastic wrap to serve as a mold release and keep the car clean. I used expanding foam to fill the voids. The part ended up being too bulky after gluing everything together. The epoxy didn’t sand down very well either. I keep the failed part on hand to remind myself to slow down, take a break, and start over if I find that the quality of my work is not good enough.

A second attempt worked much better. I glued up and carved a block made of pink foam-board house insulation.

The trick to a smooth finished part was to coat the foam with a mix of epoxy and a filler called micro-spheres. The filler with spheres is easy to sand, and the mixture doesn’t weigh as much as straight epoxy. Once the core is smooth and sanded to the correct shape, fiberglass cloth and epoxy layup gives a light and strong part.

Finished with primer and flat black paint, the tray blends right in with the stock grill.

The last detail to weatherize the motor compartment is an edge grip weather strip that forms a seal with the deck lid. We get a lot of rain in the Pacific Northwest. I’ve been driving the car daily for a while and everything is staying dry in the back.