protecting inside of frame rails?

[67goatman455]

I am going to box my frame rails on my A-Body but i'm wondering how to go about protecting the inside of the rails. I will be powdercoating the frame but i'm not sure how to go about getting the backside of my filler plates protected. any ideas?

[astroracer]

Clean it all very well and spray the inside of the rails with rust converter and paint them before you box them. Grind it back a bit for welding and, when you are done with that, re-spray the rust converter inside to coat the welds and welded areas. Leave a few open holes for access and provide drainage so water won't sit in the rails.
I would leave it like that, without rust proofing or any coatings, just to keep from holding moisture under the coatings. Letting the water drain and allowing the substrate to dry out is key to limiting the rust animal. Coatings tend to hold moisture for a very long time and never "dry out".
MAS

[67goatman455]

wow, thanks. ill try that. I think ill do it with POR-15 for best corrosion resistance