Finished converting the inner plenum . It took four separate passes with the phosphoric acid. The nature of the surface rust took more time with wet acid to covert than anything else i have worked on. I need to reapply one more time to disolve the coating the acid leaves behind, then cleanup with fresh water. Still not sure if i want to paint with mastercoat silver or leave it to fog with a wax/oil product.
I struggled with the spot welds along the top of the cowl and decided to cut it flush with the flange for the upper panel. No way to get a seam splitter in that space due to the vent duct obstructing access. If you look at the patch panel, you will see what i proved that no way was that new cowl panel going to slide under the upper panel flange without bending the flange outward, mangling the panel. I plan to cut off and butt weld the top seam to the right and left of the fender mount. I will try to get the section of cowl flange behind the fender mount to slide in place. Wish me success.
Sorry, no pictures for this update. I neutralized the acid and washed the entire plenum followed up by wire wheel which removed the converted iron down to grey steel for probably 90% of the plenum. The stubbord 10% remaining had rust under the converted iron phosphate.
Decided to whip out my lil sand blaster to cleanup the remaining rust but suprise suprise, my cheapo harbor frieght blaster has a hose that has completely degraded and fell apart after just one year.
Instead of knocking my head against the wall, i reapplied phosphoric acid and will order a “real” hose for my little blaster and go on vacation for a week.
Did i mention that trying to purchase Master Coat silver encapsulator paint has been an epic fail. I’m on the list to be notified when their product comes back in stock. I received an email and went to try to purchase within an hour and they were out of stock again. Heck of a way to run a business. I call these kinds of businesses hobby businesses, cus they don’t exist to make $$.
I emailed eastwood and asked about their encapsulator platinum only to get the same response as they give about the epoxy primers. You must get all traces of acid and acid byproducts removed and fully neutralized to ensure adhesion. I’m real close to giving up on paint sealers and going with lanolin products.
on my 58 apache ,I replaced the whole pillar just above the top hinge down to the step. That upper flange over the pillar can be separated with a mutilsaw tool. I would not try and drill out the original welds. That fender bolt hole placement is crucial
Thanks for the input GP. Stella’s upper cowl was not as bad as yours. I already have the cowl cover ready to go in. I decided to sand blast the inner plenum and hit it with EP 2 stage in a rattlecan before i reinstall the cowl cover.
The phosphoric acid converted most of the surface rust. It took 6 applications to get where i decided to blast the entire plenum so there is no issue with residual acid. Shoulda gone that route to begin with. Waiting for the epoxy to arrive. While i wait, i replaced part of the front step filler panel.
Last edited by KevinS; 09/01/20258:58 PM. Reason: Add photo
Started fitting the lower hinge pocket and the lower cowl plenum panels today. I have them tacked in but need my small disc dremmel to work in the tight area. Of course, my dremmel died.
