What would you recommend I use to plug up some of the screw and bolt holes on the firewall to keep everything water tight. For example, I'm replacing the stock points ignition with the HEI. After removing the stock coil, there are holes in the firewall that I need to plug up. I have various other screw holes I need to plug up as well. I would someday like to weld on new metal panels or replace the entire firewall. But I don't really have the time to do it right now. Any suggestions, opinions, etc? Thanks.

I would highly recommend a good elastomeric caulk. This product is paintable, waterproof, permanently flexible, long lasting, and can be tooled into the hole and feathered on the visible side. I recommend Tremco (Vulkem) brand without fibers, but I am sure other brands are also good.

JB Weld 5 Minute Epoxy. You can even sand it after it dries.

And it's pretty dang permanent. I plugged all my "extra" firewall and floorpan screw holes installed by previous owners. After sanding and painting, you can't tell they were ever there.

JB Weld is an excellent product. Thoroughly clean the metal before use. It bonds best to bare, clean metal. I have found that if it is feathered too thin, it will sometimes crack or pop loose, especially on panels that flex.

Elastomerics will bond well to paint, but not to grease. It will flex and will never crack.

Where can I pick up the Elastomeric Caulking? Would it be available at the auto parts or hardware store? Thanks again for the replies.

Tremco Vulkem sealants are available at building supply companies and RV dealers. 3M elastomerics are available at home centers. Both are excellent quality; check the label to be sure you select a paintable version.

Yellowbird, do you think the sealant would work on a few pinholes I have in one of the rear floorpans that I have? I really don't want to cut the metal out for the half dozen pin holes that are there.

Elastomerics will seal if you grind off the rust, but you might want to go with an epoxy product to add strength, like POR.

Would a metal filler like this work?
http://www.eastwood.com/shopping/pr...=PRODUCT&RS=1&keyword=metal+bond

Thanks Vikki.

Thanks Joe, that may just do the trick. I need to order more chassis black from them anyway.

I`ve used some black silicone on my extra holes...and in some smaller scew holes I just put small screws, touched off w black paint...