Well I am thinking of some things I may want to do on the motors of my boat. Not that they are having any problems but they do have over 800 hours on them. So what would some of you do?

I have 454 mags. I don't really want to do any thing crazy to them, but if I could get a few more ponies that would not hurt either. So if I was to freshen these motors what would be some parts you would reccomned I use. I am really thinking of just getting parts as I have the money then at some point put it all together. Also gonna paint the engines to match the boat at that time.

what year are they ?? Jamie / Lakeside

88

Jamie, I posted this at TBM to so don't reply to both

Hey I guess I do have a small following Now if I can only get some groupies

Have you thought of working it into a 496 ?? Like changing the crank stroking it?? You could upgrade the heads to Pro top lines or Merlins. Give it a mild cam & put a better intake on.. It would definiley wake it up a bit without going crazy.. Also if you have enough room another option is to rebuild it & bore it appropriatley & run small intercooled blowers like Blower shop 250's.. If you want to talk about it give me a shout.. Jamie / Lakeside 570-639-2628

If you're happy with the way the boat runs now I probably wouldn't change much.
I'd recommend bumping the compression ratio up a bit, from 8.75:1 to the low-to-mid-nines, which will still run on pump gas. A mild hydraulic roller cam is a nice upgrade but not a necessity.
You can upgrade to aftermarket heads for about the same money as the stock heads will cost to refurbish but again, it's not necessary.
Assuming you have the stock 1988 exhaust you will want to take a good close look at it to be sure it won't cause problems due to corrosion. If you're going to drop a big chunk of change it will be in new exhaust.
You can be as mild or wild as your budget will allow but mild is always most cost-effective way.

read these

http://www.offshoreonly.com/forums/s...light=nobudget

http://www.offshoreonly.com/forums/s...light=nobudget

Hey Griff,

Would you still have that parts list. I would love to see it if you do.

I only did a top end refresh on my engine. All the part numbers I have are listed in the threads I posted. If you're doing a full rebuild, I would bump the comp ratio up to about 9-9.25. I shaved my heads to bump it to about 8.9.

Do you still have the stock Merc exhaust system on your boat?

If it's the Merc 454cid 365hp mag engine, then they have all forged parts, pistons, 7/16" rods, cranks. They also have the aluminum hi-rise dual plane intakes and GM rectangle port heads. You can stay with those heads or upgrade to something like an aftermarket oval port Merlin head or if you feel you must have a rectangle port the Dart Iron Eagles in 308cc would be good. Just be aware that the GM rectangle heads have a tendency to CRACK between the seats quite often---whether you keep the GM heads or go with the aftermarket heads I just mentioned, have a light, simple bowl/pocket port job done to the heads. Add a mild hydraulic roller cam, Crane Gold roller rocker arms, 9.1 comp ratio and it will give you a little extra power than what you had with the stock engines then that will do it............and I'm not sure if you have the buck$ for this, but you'll REALLY feel a kick in the pants if you have an aftermarket exhaust system of some sort on your engines like a CMI E tops, or even a cheaper GIL's or Stainless Marine exhaust system, etc. Hope this has helped.