Head bolt sealant.

[Pinger]

A couple of guys on a UK (LPG/propane) forum are rebuilding boat engines. One is a V6 Vortec, the other is 302 Ford. Both have head bolts that enter the water jacket. The question is 'what to use as a sealant?'
On another thread I saw a Loctite product being mentioned. I know you guys reach for the Permatex, but it's hard to obtain in the UK. Any alternatives to Permatex?

Also, before posting this I found a thread re TTY (torque to yield) and if I've understood right, if the V6 Vortec in question's bolts have 1/2'' heads then they are TTY and have to be replaced - and that new bolts have sealant pre-applied. Is that the case?
TIA.

 

[Hipster]

Most marine engines are just a marinized version of a standard long block. Normal Gm stuff still applies. I reference a GM manual for torque methods and specs. If they torque to a base value and then degrees for final, I'm already assuming tty fasteners despite what every one else thinks even moreso if , narrowed shank. New ones come with sealant. Mercruiser manual will give you a ft. lb. conversion table for final toque values, but imho, that can lead to stretched fasteners with less clamping force. Stainless head gaskets for raw water cooled.