1973 Tsunami to Center Console Conversion

[jgrisham]

I have absolutely no experience with I/O's, and I am a little overwhelmed prospect of re powering.

I was kinda thinking I could find a used GM vortec engine and buy a simple harness/pcm and drop it in, Is this doable?

Also the engine mounts seem to be hollow and kinda flexible kinda like they have been compromised. What would be the best way to go about fixing this problem?

I bought the boat without an engine so I did not get to learn by disassembling, but how is the engine actually fastened to the mount?

[kneedeep]

yes,i think i used a 1/2''roundover bit on the inside edge. used a mold release wax/paste. you could use plywood or mdf with formica for a one off mold. the pvc board i had was smooth on one side wood grain on the other. as far as the i/o goes i can't help you that was the first thing i got reed of. outboards for me. in my boat the motor mount for the i/o was about 4-5 2x6 stack on each other then glassed in. seems to me your giving up a lot of space with a i/o cover,leaning post and a cc. or are you going with a pilot house?

[jgrisham]

Kneedeep, I kinda like the idea of being able to repower for 2k or less, Pretty hard to find decent outboard for less than 5k. I definitely won't be doing the waltz on board, but it should still meet my needs. Do you think I should cut the whole mount out and start new, or should I cut the top off and pour in seacast or such? Is the motor lag bolted, or where studs/bolts placed when the mounts where set?

[Blue_Heron]

Originally Posted by jgrisham

I have absolutely no experience with I/O's, and I am a little overwhelmed prospect of re powering.

I was kinda thinking I could find a used GM vortec engine and buy a simple harness/pcm and drop it in, Is this doable?

Also the engine mounts seem to be hollow and kinda flexible kinda like they have been compromised. What would be the best way to go about fixing this problem?

I bought the boat without an engine so I did not get to learn by disassembling, but how is the engine actually fastened to the mount?

You don't want to use an automotive engine in an I/O for a number of reasons. First, automotive starters and alternators aren't ignition protected. Second, the cam/valve timing is different on a marine engine. You should be able to find a decent used marine engine for under $5k.

The engine mounts to the inside of the transom assembly and to the forward motor mounts. The forward mounts are height adjustable. Do yourself a favor and buy a factory service manual for the engine and drive.

Dave

[kneedeep]

j i would take a die grinder with a 3'' cut off wheel and cut 1 1/2'' down from the top all the way around it and remove the top layer. see if it's solid wood ,if so add a new top layer and re glass. if it's wet keep removing it. the mounts in my boat were lag bolted with ss lags. you may find the need to move the center console a little farther forward to offset the wt you removed from the bow and maintain your waterline and may pick up some space behind the leaning post too

[jgrisham]

Thank you both. Blue Heron, how can the timing be different? I can definitely see needing ignition protected components however. Thanks

[Blue_Heron]

Originally Posted by jgrisham

... Blue Heron, how can the timing be different?...

Less overlap on the exhaust valves so it doesn't suck water back up the exhaust. I'm not much of a motor head, that's just what I've read.
Dave

[jgrisham]

Kneedeep, do you mind telling me what type of resin you used on the rails? I am sure epoxy is recommended but will polyester/vinylester get it done and stand the test of time? Its a pretty big fabrication to use all epoxy!

[CATmech945]

You can use an automotive engine, I would just suggest changing the camshaft to a marine profile. Usually a high lift, short duration with a stretched out lobe separation designed for torque. Not to go all technical, but usually an R/V cam works well. You don't want a choppy cam like in a street car because they only flow well at higher r.p.m.'s. You'll want the cam to be smooth and designed for power between idle and say 4800 r.p.m. or so. It's way cheaper to change a cam than buy a "marine" engine if you're trying to save a few bucks. Use marine electrical equipment such as starters and ignitions like blue heron said but you can use an automotive engine. I've been doing it for years. Look into freshwater cooling though. It's worth the thousand bucks or so.