was told I had to drill out the throtle plate hole to 1/4 .

Well thats what I do for a living been a GM certified tech for 25 years, hoping I could wrap up both engines in a weekend,
I see from reading the merc manual I dont have to drop the oil pan to remove and reinstall the timimg cover and all gaskets are reuseable,is that correct?

Well, I'd love to hear you could do that in a weekend! If you're not taking them out of the boat which I highly recommend, I think it will take most of the weekend for you do completely finish one of the two.

Not all gaskets are reusable. Best I remember, you'll need some extra valve cover bolt seals - those little rubber grommet type pieces.... They usually break apart on you if you don't go real slow. I go through a couple here and there.

You'll need some exhaust manifold gaskets - I bought the stainless ones from GM.

You'll need head gaskets.

Intake, valve covers, timing cover are all o-ring type and can be reused no problem.

You may need to buy the metal-backed seal from Merc that sits between your circ pump and the bottom of the cross-over. They take shape and it's not worth trying to get to it later if it leaks. Check your heat exchanger seals carefully. May want to replace them if they are not nice and soft etc..

A 25 year GM tech should not have many problems. We've done it more than once and I can tell you that it's a mess to try to do it in a "nice" boat. If the boat is a "beater" or you don't care then it will be easier.

I take it you have excellent access all around the engine itself in your rig...

If you can finish two engines in a weekend that'd be a record. Good luck and have fun!

:coolcowboy:

Also, you have torque-to-yield head bolts. You can argue with someone about whether or not you want to replace them.

Merc specifically says not to reuse them for what that's worth to you. Don't over torque on reinstall. You'll see not much meat on that deck.

Do yo have DTS on the boat??

Heads will stay on the engine for a cam change

I have about 3 feet in front of the engines and the back seat so engines are staying in the boat.

I know on the 5.3 gm engines we have to remove the heads to get the lifters out but the 8.1 on the trucks we dont have to remove the heads,so I was not planning on messing with cyl heads or exhaust manifolds,

something different in the marine 8.1 that I dont know?

and its cable shift and cable throtle no DTS

Naw I just figured you might slap a nice set of heads on there while you're that far. I only asked bout the DTS cause of the computer flash

What I wouldn't give for that.

Not if he gets the bug. I was gonna do that cam change too remember??