Thanks for all the great info. I've just returned from an enjoyable and needed weekend away.....
Sounds like a forged crank isn't needed and isn't readily available, so I'll drop that from the spec list though the ones from Brazil sound interesting enough.
Is it possible to have a billet crank custom manufactured somewhere at a reasonable cost?
As for the roller cam, I read somewhere they reduce friction which suggests some reduction in heat production. I'm sure I can source one somewhere as a custom order item. I note that Mercruiser now installs roller lifters on lot's of their newer V8 power offerings. Maybe an engine that spends it's life running at 3200 RPM isn't going to really benefit from it anyway.
I know that getting the cam profile and valve overlap specs correct is important otherwise you get too much heat buildup from the continuous duty cycle. You can still buy replacement cams for the Mercruiser 6 cylinder engines from a number of sources. Perhaps I'll simply use one of them.
Headgasket failure due to corrosion is a common problem with marine engines. That is why a stainless steel core headgasket is needed. Felpro does offer them for sale.
Any sodium filled valves that I can get my hands would be a benefit. Hopefully, I can source them in the factory spec diameters. Any suggestions on where I can source these?
Can anyone suggest a competent shop to build an engine for me. If I get the Bertram 25 I've got my eyes on at the moment, I'll need two engines, not just one.
Finally, I don't consider an engine with 8.5 or 9-1 compression together with any of the modest mods I've proposed as being seriously hopped up. Mercruiser did build a 292 marine engine for one year in 1974 and rated them at 200 HP intermittent duty and Crusader also offered them rated at 185 HP. I'll speculate for a moment that there wasen't going to be a big market to sell parts for these units and thats why they discontinued to offer them. I imagine it was easier then as it is now to sell a V-8 than it is to sell a vanilla inline 6 even thought I believe that the 6 is better suited to the job.
