Engine Rebuild or Replace? 1974 Marinette Sedan 32ft w/ Twin Chrysler 318's

Hi everyone, I'm new to boats and Just bought this '74 Sedan. The boat itself is in FINE shape, however, mechanically it looks like the motors (the blocks) might need rebuilding or replacing (knocking left eng', right side not firing but turning over). This comes from a "mechanically inclined" friend, as an initial look at the situation.

Here's my problem:

1) As far as being "cost effective", can I just swap the short-blocks w/ street motor blocks (some good ones w/ low miles), retaining all the original MARINE top-end stuff, or.....

2) Should I just have the blocks rebuilt, heads reconditioned, replace all other components (i.e., oil pump, etc).

I'm currently in Iraq (DOD Contractor), so I'm having to coordinate all this from here. I'm having a certified mechanic go inspect the engines to give me a "professional" diagnisis, so I'm just thinking/planning ahead just in case.

Any advice on this endeavor would be much appreciated.

Thanks, ATCDave

Dave:

Buy two long blocks, swap over the valve covers, intakes, distributors, etc. and toss the old blocks out. You'll be way ahead in the long run. Mopar long blocks are cheaper than Chevies, and car motors need lots of part swapping--and that's just for the standard rotation motor.

Jeff (!985 Marinette 32 foot Sedan)

If previously raw water cooled, and particularly if in Salt Water...... NO!
Begin fresh with automotive cores.

Remeber that one engine will be RH Reverse Rotation, and requires some special attention in that reqard.

.

Thanks guys. Well, the boat IS raw water cooled, brackish'/saltwater. Since this is a twin screw w/ the separate motors and trans' facing rear (they appear to have Borg-Warner AS1-71C Velvet Drives w/ reverse I believe?).....I am assuming both motors rotate the same direction....is that right? I'm unfamiliar with this reverse rotation situation.

I'm pretty pissed the previous 3rd owner let the maint go for about a year or so, not I'm having to "investigate" the extend of the neglect. I do know I'm going to have to entirely REPLACE the fuel delivery sys components/lines/filters, etc, and remove the cylindrical aluminum fuel tank (for proper flushing and new pickup lines, they were using COPPER TANK LINES, IS THAT OK?).

For what I bought the boat for (7K financed), and it's structural/aesthetics condition, I really thought it was a good deal, and however was not expecting extensive mechanical problems, so I'm trying to gauge If I am going to have to invest more than 5K or so in repairs. Even then, no biggie.

Thanks again guys.
ATCDave

Here's my 1974 Marinette and a pic of the engine bay.



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Here's my 1974 Marinette and a pic of the engine bay.

Now we're in a situation where the boat is stuck at Lake Ponchatrain, LA, (beside !-10 bridge, private slip/dock), motors not running, 50 miles across the coastline from Biloxi, and trying to figure out through some friends how to either get it towed to Biloxi ($$$) or to a yard in New Orleans and dry-docked, and THEN I don't know anyone to trust to work on it over there. Sheesh, makes me want to get back to the US now. lol

Hopefully with a bunch of my boating friends brainstorming we can come up with a plan. Question, if we were to tow it back along the coastline ourselves, what would some of the towing "hazards" be, besides not drifting into the towing vehicle? Is this illegal? Any experience or ideas on that crazy idea? Wait, duh, My neighbor is MS State Marine Police, lol, just remembered that, I'm sure he'll know that legal part, haha.

In the mean time, I'll have my wife and friends start looking for a couple of 318 long blocks in GOOD shape w/ LOW miles. Thanks again guys. ATCDave

Oh boy. Wow. Well, for starters, read the Marinette owner's manual for the engines here.

You are in a real pickle and it's time for a reality check. You have to think long and hard about your long term use of this thing. If you are going to keep it for ten years and use it, and enjoy it and not have to be working on it every time you step aboard, then I fear the best option for you is to bite the bullet and invest the 8-12 thousand it is going to cost for a complete repower. The pic does not inspire confidence in the shape of things. I hope the rest of the boat is absolutely pristine. Probably not.

What will happen is that the engines will just be the start of something way larger than you planned for. With new engines you'll need all new wiring, instruments and controls. That will mean also that you will put in new shaft and rudder strut seals. Might as well gut the engine compartment and clean out all the crud and paint it. You'll also want to put in new cutless bearings in the struts and have the props sent out to be checked.
As long as the engine bay is opened up, go ahead and fix all the thru hulls and the plumbing. Gonna have to install a holding tank system if it doesn't already have one. That probably means all new hose and water tanks....Marinettes have issues with window tracks and the aft deck, as well as electrolysis and RF interference.

Do you see where this is going? I can understand if you are a Marinette geek and have to have one at any cost. Even all completely redone they don't go for much as far as resale goes, so you have to be in it for the love.

You should probably not waste your energy looking for used engines, it's just too risky to put in a lump that you may have to pull back out again in a year or two. You must throw yourself on the mercy of a good yard that will do the work the right way and in a timely fashion. Whether you realize it or not you are already "all in" so don't try to get out cheap cuz you are beyond that point. If you are getting cold feet best find another buyer pronto.

Also, Marinette will do a complete overhaul. You have to ship it to Michigan, and they will take it apart and fix it up and ship it back to you. It will cost the moon but you'll have more or less a new boat for far less than it would cost from a dealer.

www.marinette.com
www.marinetteboat.com

A nice example for sale here

I believe that you first need to come to terms that a boats are rarely investements, and are almost always expenses. I'd not even consider re-sale value as part of the equation! We simply use it up in the form of enjoyment!

Secondly, learn if your Stbd engine is RH Reverse rotation. My guess would be that it is!
Have a pair built, or machined and do the assembly yourself.
The RH Reverse rotation engine offers some subtle differences, but nothing that can't be learned if you have the skills in the first place.

.

As usual, Rick is Right: The starboard motor is the assbackwards rotator.

DON'T buy a used motor! (The replacement of them--though those glass sliding doors--is a royal pain in the butt! I've been through that twice with my 85 Sedan so I know of what I speak.) You can buy a good long block for well under 2,000--they're cheaper than Chevies. Finally, since this boat is (I assume) used in brackish or salt water, you need to think about replacing the exhaust system as well, so do a major think session, with cost estimates, before proceeding further. Okay?

Jeff

PS: Marinettes are nice boats with few faults and last a long time with minimal maintenance. If you want a "Keeper" then that's the boat for you, so it'll be worth spending the money.