Budman II

iTrader: (1)

Are you talking about the Scat cast steel cranks? Keep in mind that these are made with a much higher grade alloy than most of the factory cast cranks from back in the day. Still, if you are thinking that there is a chance that they might see boost in the future you would probably sleep easier with forged cranks.

murfman

I don't see boost in my future. At least not in this boat. And yes I'm going Scat either way. I have one in my 392 Stroker GCSRT-8. It is a nice piece. Every dimension was dead on, not in tolerance, dead nuts on.

vintage chromoly

iTrader: (3)

My pantera had a 426 Hemi in it from 1979 to 2010.
The previous owner put it in the boat in place of a 350 chevy.
He kept the Hemi for a 1964 savoy he's building.

tpabayflyer

Looks like great minds think alike, I have an 09 GC with a 5.7 and a complete SRT 8 exhaust and rear bumper.... It's going to get the stroker crank treatment at some point with the Compstar 4.080 setup.... Tow's my Donzi with ease! Very interesting about the hemis in boats..... Magnum heads with 62cc chambers will bring the C/R up so you might have to get some dish pistons..... I say let it rip!

murfman

Seeing as how they are Mopars and I have not found an easy way to bolt them to Mercruisers I will most likely stick with the Volvo/Chrysler 270 outdrives and adding a home made trim. Keeping it old school.

CDShack

Cast cranks are ok probably up to your 400hp level. Boats, while under constant load, don't suffer the torsional shock of autos and trucks launching. If you HAVE a cast crank, then it's probably ok. If your BUYING a crank, no reason not to throw the extra change at it and get the best.
As was accurately stated, 400hp makes you want 450hp, 450hp makes you want 500hp. Forged crank 1) keeps that option open and, 2) is just good insurance regardless!

Check with Comp Cams, ask about their recommendation for Marine Cams and ask if they have some not in the books. In my Scarab, I have a set that aren't listed, just build numbers that were dynoed and developed for offshore motors. Comp Cams is generally super helpful!!! Lope separation is important to stop water reversion, and 112* is getting close! jmho.

murfman

I 'm going to go with Forged cranks, I found a place that sells Forged K1 cranks for 629$ and Scat forged cranks for $ 719, which is way better than I was first quoted. As for cranks , I've found Scat, Eagle, K1, and Molnar.

murfman

With the 360 blocks the motors work out to be square, 4" stroke and 4" bore at 408 CU In. I'm thinking a cam around 270 deg advertised with 110 degree lobe seperation. There are a few choices both Iron and aluminum for cylinder heads. For intakes I think I'm going to run the Chineese knock off air gap dual plane intakes as they are set up for the Magnum heads but have the early style water bypass hose setup which will make plumbing easier. I am thinikng a closed cooling system but it seems many offshore boats are raw water cooled, is there a reason? I think I will stick around 400-450HP as I have heard that is about the limit of the Volvo Penta outdrives. Am I missing anything?

Trash

Plenty of Merc motors came with cast cranks, even on the Magnum motors. If HP levels are reasonable along with rpms under 5200ish cast should be ok. But....as others have said, any future mods for elevated HP it would be prudent to have a forged crank.

dereknkathy

what are u running for exhaust. that 110 lsa cam will have a lil too much overlap for stock exhaust. will revert (suck water thru exhaust at low rpms).