KevinGross

I am taking content out of a street car as it becomes a dedicated racer. With the heater core, etc gone, there are holes in the front firewall needing filling. Round plugs (from Porsche) will work in many places and are cheap enough, but other holes will require fab'ing some simple rectangular (etc.) lids, thinking thin aluminum. Looking for recommendation as to how to best gasket the aluminum lids -- is there a good, flexible, chemical-resistant sealant most in favor? Or a tape-like solid gasket that can be used? I notice Porsche has a sealant in their parts diagrams, 999 915 337 40, but am unsure of its qualities, can't pin down the original product. Cheers,

Blue Chip

When I helped a friend on his SPB we used aluminum with pop rivets. No sealer used.

CL944135I

Aluminum with rivets or screws works well and I use a seam sealer available from any auto parts place or even order it online from Eastwood or a similar company. You do not want fumes getting from the engine bay into the car, I would also only use plastic plugs for small holes as fire will go through them very quickly.

Matt Romanowski

I don't know brands, but expect SEM, to have structural body adhesives. You could simply glue the patches in. If you want ghetto cheap, I'm sure JB Weld would do it too.

himself

I just looked at this the other day for my SPB - under the PCA rules, firewall openings need to covered with metal covers that are mechanically fastened (unless there is an OEM non-metal cover). Adhesives are expressly prohibited. I think screws / rivets are probably the most common.

-td

Matt Romanowski

Interesting. I like the Seals It products if something is going through. For panels mechanically fastened, I like using Rivnuts instead of sheetmetal screws.

fatbillybob

fixed plugs because glues melt in fire the whole point of a firewall!

Matt Romanowski

3M and others offer adhesives that can deal with the temps, but it would be impossible for tech to know if it's the good stuff or junk adhesive. Good point.

KevinGross

Thank you everyone for the feedback and info. If I had been less cloth-headed, I would have remembered to check with my Aircraft Spruce catalog before posting here! My take is that, per the rule book, mechanical fasteners (screws, pop rivets) are needed to make sure the lid stays in place. To Matt's point, an adhesive gasket or sealant will ensure that fumes and liquids don't enter the cabin. So do both: fasteners to retainer, tape to seal. ASSC has an inexpensive Zircoflex double-sided tape that appears to be a good choice for sealing; there are also liquid firewall sealants available from them and other sources. ASSC also has several different stainless steel sheet metal products they label as "firewall sheet," as well as aluminum. Will give them a try.

Good points also about rubber / plastic melting in flame. I'll stay clear of them as much as possible, may resort to a fire-resistant liquid sealant if there are existing pass-throughs needing attention. Cheers,

Plavan

This...... https://www.homedepot.com/p/GREAT-ST...3992/207077797

KevinGross

Chad, thank you!

rlm328

If you have the engine out weld your covers in place.