Crankcases to paint or not?

Hi Ron,

Mine were painted timing bulge too. When I stripped the paint off porosity raised it's ugly head. I often wondered was that the reason why only some were painted. Sealed the leak with devcon aluminium plastic metal.

Dave

My cases on my MK2A showed evidence of silver paint when I bought it, long gone now. I tried to paint the head silver when I last rebuilt it but it did not last long enough to consider trying it again.

They were indeed painted with a thin single coat that provided reasonable corrosion protection but didn't withstand abrasion too well.

My feeling is that a nice vapour-blasted surface stands up quite well but painting might be a good idea for anyone doing lots of miles on salty roads.

Hi All.

Paint and Porosity.

Ferrari cars up to the late 70's (possibly even later) had the engine blocks painted then had the excess paint wiped off while still it was still wet. Left a lovely red 'crinkle finish' to the blocks and sealed off the holes! I have used this method on one of my (non-Norton) bikes when oil seeped through the cases and it worked really well (but I used silver paint).

Any cases that have been blast cleaned with an abrasive medium are likely to open up porosity.

One way that many car companies use (used?) to seal aluminium heads and blocks was with a very low viscosity "resin". Parts were placed in an autoclave, the air was evacuated and while in the vacuum they were dipped into a bath of the resin. When the autoclave was reopened, the air pressure would 'push' the resin into all the nooks and crannies. After the excess had run or rinsed off it was cured somehow, leaving the outside looking just like a normal casting.

Regards,

George.

Hi Ron,

I have had my 850 MkIII from new (1977).

The head and cases were painted.I think it was closer to a cream colourwhen new. It was certainly not silver.

There is still some paint left on it but it is too cold to go out and look.

Regards

Tony