Panther

For the mains you're actually within Mercs spec for the clearances on mains 1-4 and the rods. Tight on #5 if you're only coming up with .0020. I don't build mine that tight but then again, I'm not used to low HP engines.

mggdoors

That is what I seen too. So I assume as long as I run a low viscosity oil I should be fine? Btw. Does anyone have any guess on hp

MILD THUNDER

iTrader: (3)

375-400hp would be my rough guess.

F-2 Speedy

iTrader: (6)

Scat cranks can be a PITA to get balanced, these guys will get you in the right direction, good luck

mggdoors

I ordered it balanced from scat as a rotating assembly

mggdoors

Really only 375-400? So what is holding it back.

Mr Maine

I think what will hold you back is the heads and cam. With 489 cubes you will probably peak hp at 4600 or so. Should have good torque but peaking at lower rpms will limit the hp number. Just my thoughts, you didn't give compression numbers or valve sizes.

1BIGJIM

iTrader: (1)

I have built several 496's. A huge factor you never mentioned is what exhaust. Cam is way to small. I had custom cams from Bob M. 114 center line with 600+ lift that idled like a kitten. I used 800 D.P. on all of mine. Easy 450Hp +. That is a big boat. Call Bob he will get you pointed in the right direction with a cam and anything else you might need.

mggdoors

It has aftermarket stock replacement exhaust from I believe hge Compression is 9.5:1 valves are 2.08 1.72. Flow at .500 intake 265 ex 170

GPM

Maybe this will give you a starting point, the 4.25 stroke will lower the RPM range. I copied this from another thread. Stock Mercury 440HP 454ci cyclone camshaft
293/310
232/239
.549/.558
110 LSA