Mercruiser 3.7 Upgrades, what Gaskets??

25thmustang

Lieutenant Commander
Joined
Mar 20, 2008
Messages
1,849
Hello,

I have recently begun work on my boat. I will start with where I am, what I have and why I am doing this work.

The boat is a 27' Express Cruiser with twin 3.7LXs. The previous owner was not a boat owner and proceeded to seize one motor, and hurt the other to the point of not running. I purchased an older Wellcraft with two 470s (the same basic motor). The motors I have to go in are 2 bbls, cast iron manifolds, and 3" heat exchangers. The bad motors in the boat have 4 bbls, alunimum manifolds and 4" heat exchangers. These parts have all been removed and are being cleaned and checked before going on. Now on to my question...

What gaskets do I need to perform the swap? I understand the major ones, intake to head gasket, exhaust to head, riser to exhaust, carb to intake, and the plan is to put in new cam seals, although the current ones do not show any leakage.

Are there any smaller gaskets that I will need? The reason I ask now, is because I plan to order all the gaskets at one time, to save on shipping and to try and get the motors ready to drop in ASAP.

Anyone with experience on this who would like to share, it would be greatly appreciated.

Thanks.
 

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,830
Re: Mercruiser 3.7 Upgrades, what Gaskets??

You didn't say that you are putting on new head gaskets. Since you are going to all this trouble, now would be a great time to pull the heads and slap on a couple of new OEM Mercruiser head gaskets (and have the heads checked out), they are engineered specifically for the 470, and have added beads of sealant on the gasket surface that I do not believe are on after market gaskets. Could prevent trouble down the road.. Wow! TWO 470's welcome to the club:D!!
 

25thmustang

Lieutenant Commander
Joined
Mar 20, 2008
Messages
1,849
Re: Mercruiser 3.7 Upgrades, what Gaskets??

That is a good idea, but the motors I will be using were rebuilt before my purchase of them. This included head gaskets. I am not sure what the PO used for gaskets, but I do know they are fresh.

Yes two 470s... should keep me on my toes!
 
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