Replace Merc 5.7 L with GM crate
 

I recently purchased a 1996-2000 GM 5.7 L new longblock with vortec heads to replace the original block and heads that were cracked(frozen). I know this subject has been beaten to death before but I have a few questions around replacing the cam and lifters with the marine cam and lifters from cracked block. Both are hydraulic roller and the same vintage block. The heads on original mercruiser were 64 cc 1955-1986 vintage while the vortec heads are 64 cc also. Will I need to replace any other components in the new vortec heads ie. pushrods, springs, valves or lifters. The new crate engine is the 3/4 - 1 tonne application so I am confident the crank, pistons, rods and bearings will be as good of quality as their marine counterparts. I will be going to FWC and am in freshwater 97% of the time. The new crate engine has brass freeze plugs from factory. The previous engine had 12 bolt 2 barrel manifold rated at 190 HP whereas the vortec is rated at 260 HP with 8 bolt 4 barrel. Will the cam specs(not sure what they are)from the 190 HP engine have any ill effects on the new vortec setup. I am a new member and hope you will excuse the long winded explanation but other forums I have looked at on this topic were missing alot of crucial info that I hope I have touched on. Hopefully somebody will have the time to wade thru the above and provide me with some direction.

Re: Replace Merc 5.7 L with GM crate
 

I would not use the cam out of your old engine.
Try to find out what the specs are of the cam that is in the crate engine you bought.
Then post the specs here along with you boat specs...
You will get lots of input as to if the cam that is in the engine will work or not.
If not, then I would purchace a new "marine cam" from Comp, Crane, or other.
My guess is that the cam that came in your new engine will work fine...
Good Luck! :drink: