Matthew booulton

OK serious question what differs a merc cruiser engine block from heavy duty GM block .same with heads...

phragle

iTrader: (3)

clearances

Matthew booulton

So basically if I rebuild Chevy with marine crank and rods and follow marine tolerances I should be good right...I have pair of 83 454 blocks and heads but plan to up grade to marine heads ( can get bare set reasonably priced.then put them on the four bolt blocks...good merc engines run around 4K each.. for that with these blocks I can have some good HP motors figure north of 450HP a piece

f_inscreenname

A 83 truck 454 to a 83 Merc motor, crank and rods and pistons are the same as is the block and heads. Cam and some gaskets are different as is the bolt ons (carb, dist, starter, etc). The Merc MIE340 from around 1983 was just a truck motor with a different cam.
To answer the question of what you have, get us some head casting numbers and take the pan off and find out if they are 4 bolt blocks. Are they stock motors with cast everything? Even without performance gains using a aluminum intake and 496 aluminum exhaust will save you about 300 pounds for 2 motors.
There is a lot of helpful folks here with the map to where you want to go. We just need to know where you are before we can tell you how to get there.

Matthew booulton

Thank you very much .yes they are 4 bolt mains..heads say they are the peanut type..was figuring the merc heads would fit on these engines with a good set of valves and marine cams I have normal torquer intakes for them and her fist...yes I know must use marine carbs..sure wish the alpha drives were up to the task but see the point in going to bravo's any specific model of bravo to avoid...? I would like to think in this configuration the 454 would make around 450 each ...so bravo what to handle these..??also what are drive showers are they needed at this level...I know next to the big boy toys this is a beginners boat at best..but I can afford to compete with them so will do my best at this level...maybe some day go to serious HP..think a Nova II can handle twin 600 HP or above?

phragle

iTrader: (3)

Where are you located??

Matthew booulton

Nevada mo...half way between KC to Joplin on 49

Crude Intentions

iTrader: (1)

I just ordered GM shortblocks for my 35 fountain. Fully forged bottom ends and 4 bolt mains. The cam will not work. It also already has brass freeze plugs. Merc used peanut ports on the 330s. Biggest difference in heads is the upgraded valves. Stainless intake. Inconnel exhaust.