'74 OMC 165 Some Mecanical Questions

Joined
Mar 26, 2007
Messages
19
Hey All!

New to this forum, great info here. I have a 1974 19' SeaRay that ive been trying to restore for years now and theres a chance it could hit the water this season. (dont believe a guy when he offers you a boat for free and says "just the head needs a rebuild" by that he meant the engine has been opened to the elements for 3 years and is completely rusted and the electrical system is a nightmare and the steering cable has exploded and the gears are all shot)

Anyway, ive got evertying about straghtened out now, new block, re did all the wiring etc. Engine rins like a top, out drive being rebuilt as i type this. My questions are this:

The block was an automotive block, do i need to change the cams and lifters? Ive been told the marine cam is a little different (more torque on the low end of the throttle) and that it needs hydraulic lifters?
Also does anyone know how to test the chage discharge guage? it jsut stays on 0, could be a wiring issue. And lastly, theres a hookup for a garden hose that goes directly onto the thermostat housing is it ok to run the water in form there or do i need to put muffs on the out dive (older stringer drive)

Thanks!
 

freelunch

Petty Officer 2nd Class
Joined
Mar 25, 2007
Messages
112
Re: '74 OMC 165 Some Mecanical Questions

Hey there, I'm fairly new to the forum but I have the same engine and stern drive as you. I won't touch the garden hose issue but I'm fairly certain that as long as you have the 4.1 250 cid straight six merc 165 you should have hydraulic lifters in there already as the automotive counterpart came factory equipped with them as well. As for the camshaft I am not certain at all, it could be any grind or design and the best way I can think of to tell is get your hands on a dial indicator and measure the lift and duration of the lobes against factory merc specs for the 165 cam. The shop manual I have states the lift on camshaft for the 250 should be .2297 inches. If the cam you have is identical to this then all should be good.
 

freelunch

Petty Officer 2nd Class
Joined
Mar 25, 2007
Messages
112
Re: '74 OMC 165 Some Mecanical Questions

Oh and from one newbie to another welcome to the forum 8)
 
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