Picked up a set of valve covers and had them blasted which revealed some pitting. I planned on fillin it in w/some bondo before painting. Will it hold up due to the heat of the engine?

Never tried it, but when I did mine they had some minor pitting. I cleaned them real good and primed, went over them with a scotchbrite pad gently, primed again and painted. They turned out real nice for 40 year old covers.

I've done it with bondo, held up fine, if you can try heavy priming the spots and then sand them down till smooth.

works just fine.

bad idea, if I were to do anything like that, I'd use lead or some sort of two-part metal epoxy, JB Weld,e.t.c.

this filler works, if you are interested. http://www.alvinproducts.com/Products/Products.asp?id=2

JB Weld is good to 500F, which is more heat than any valve cover will ever be exposed to. It doesn't feather out that great, but you can apply some primer over top of it and carefully sand the area a few times to smooth everything out.

it'll work, though I usually just use a few coats of heavy primer/surfacer (sanding between coats)

Dave

I used steel in a tube on my valve covers 8 years ago. Had a small dent. Holding up very well.

check this out Mark! Its what I will be using to bring my VC's back to primo condition.