FYI: Deck & head surface finish....

[4C FED]

I'm learning more & more as I work on my "built" rebuild.

I learned today that if the block and heads aren't surfaced with the right finish, that head gasket failure is very likely.

I was told today that the surface finish on my block was to rough and that someone used copper sealer as fill to make up the difference.

So now my block & heads need to be re-surfaced with the correct finish.

Anywhoooo, here is a link regarding surface finish:
http://www.federal-mogul.com/cda/content/front/0,2194,2442_7359_7477,00.html

 

[myclone]

I guess this could poss be classified as ones "philosophy" on engine building and there are prolly as many "proper" finishes as there are ppl building engines. That being said..........

Obviously if the surface is to rough it abrades the gasket during heat cycling of the engine but the surface must have enough "bite" to keep the gasket in place. In my experience the as supplied from the machinist finish was adequate. I guess an over sight on the machinists part would allow for the wrong finish to be produced but on the other hand that machinists "philosophy" might be to purposefully use a rougher finish for reasons only known to him (her?). Gasket selection would play a part in the proper finish also IMO. The machinist/engine builder may have found through experimentation that a particular gasket performs better with X finish in a particular application while the manufacturer suggests Y finish. It depends on who philosophy you buy into.

My personal experience has been that as long as the deck and heads are flat and there arent any obvious pits/defects in the surface modern gaskets do just fine with minimal work on the final surface finish. With alum heads, however, where the dissimilar metals have large expansion rates the surface finish and flatnes becomes much more critical (along with proper loading from the fasteners).

So... in regard to your particular sitiuation if there is an obvious defect in the finish (pits/not flat) of the heads/block then Id def have it repaired to bring the surface up to acceptable levels (acceptable to either you or the machinist) and give it a go.