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Repowering

Wannafish

Floppy Member
SUPER Site Supporter
My 36' has twin 400 c.i. Chryslers, one of which I have to replace.
I have an old motorhome I use for hunting that has the same engine (even same year) that I was going to put a marine cam in and put in my boat.

I found an ad in a local paper for 2 - 454 Mercrusiers w/350 hrs and called on them. Engines come complete and include exhaust manifolds, risers, and mufflers. They are still in his boat and I can hear them run (he bought two new 502's).

I also like the fact I would have plenty of time to "freshen" them up a little before installing them in the spring, therefore (hopefully) taking care of any problems that may be lurking.

Am I crazy or is $3000 for the package a steal?
 

Chief

New member
Are these "fresh water" cooled or raw water cooled engines and were they used in fresh or salt water? How old are the engines? Initially it sounds like a pretty good deal.
 

Doc

Bottoms Up
Staff member
GOLD Site Supporter
Good questions Chief!
I agree it sounds like a good deal. However, if they were used in salt water I'd be leary of them if they do not have closed water cooling system.
I run one 454 and have 1250 hours on it. I take it easy most of the time on it, but will race my brother most every weekend we're out, just for fun. I'll have her WOT for a minute or two, then back her down. ...didn't want you to think I drive it like a grandma! :) But the motor has handled it all fine. I considered switching to synthetic oil, but have not. With this many hours I'm hoping to get another year or two out of it then replace it with a 502. :D

I got the boat with 333 hours on it and it's done me just fine. Plain ole 330hp 454.
 

Chief

New member
Doc said:
Good questions Chief!
I agree it sounds like a good deal. However, if they were used in salt water I'd be leary of them if they do not have closed water cooling system.
I run one 454 and have 1250 hours on it. I take it easy most of the time on it, but will race my brother most every weekend we're out, just for fun. I'll have her WOT for a minute or two, then back her down. ...didn't want you to think I drive it like a grandma! :) But the motor has handled it all fine. I considered switching to synthetic oil, but have not. With this many hours I'm hoping to get another year or two out of it then replace it with a 502. :D

I got the boat with 333 hours on it and it's done me just fine. Plain ole 330hp 454.

Your rigs sounds very familiar to mine. (she is sold now) I had a Sea Ray Sorrento 25 with the 454 330 hp I/O. Below is a picture of my old rig ready to go and a bonus pic of the "Firstmate" helping out with the tie lines. :D I downsized to a Boston Whaler 13-3.
 

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Wannafish

Floppy Member
SUPER Site Supporter
Nice boat and WOW! Nice mate!

Engines are 1998 - came out of a 33' Donzi.
Fresh water cooled, and always in fresh water. Good point - Living in Michigan I sometimes forget there is anything other than "fresh" water :D .
Around here the two types of water are "hard" (ice) or wet (umm...non-ice)!

My first concern is that they came out of a Donzi - not that there's anything wrong with that - just that they may have been pushed harder than if they were in a "cruiser" style boat.
 

Chief

New member
When I used the term "fresh water cooled" meaning closed circuit engine cooling via a heat exchanger. Raw water cooled meaning the engine draws cooling water from the water the boat sits in. The closed circuit or (freshwater cooled) would be the best with raw water cooled using only fresh water. Now that I have totally confuse the discussion ;) , I agree that I would be concerned about the engines coming out of the Doni as it would be a safe bet that they were pushed HARD. I very rarely pushed my 454 over 4,000 rpm and usually (95%) of the time cruised at about 3,000 rpm.

Why is this guy changing out engines so soon? Those 502 are EXPENSIVE! :eek:

I would definitely have the owner demo the engines to you in his boat and if he wouldn't mind, let you take an oil sample to have sent off. If the engines are in generally good condition (good compression, no cracks, leaks, exhaust manifold & risers in good condition and working right, no water in oil) and you plan to go through the engines; this might well be a very good deal and economical repower.

The other issue you hopefully have considered is what costs and issues will be involve with refitting these engines in place of the Chryslers you now have?
 

Wannafish

Floppy Member
SUPER Site Supporter
The engines are raw water cooled. (I hope that takes care of that:D )

He's not only putting new 502's in, he's having them "massaged". Seems he wants to go faster! Imagine that! :eek:

Refitting -
My day job has me using portable CMM's (Co-ordinate measuring machines) which sometimes get left in my truck over the weekend:cool: . I now have cad data for the existing engine hookups (engine mounts, exhaust, raw water pickup, etc.) and will measure the 454's (if I get them) to allow me to do any retro-fitting prior to the actual installation.

For those not knowing what a CMM does - it lets the user pick points in the air (or on a part for example) and compares the distances from one point to another to come up with actual dimensional measurements.
 

Chief

New member
Sounds like money is no object with this owner. I think I would be going with 572's in that case. LOTS more torque and hp in the sweet spot.
 

Doc

Bottoms Up
Staff member
GOLD Site Supporter
NICE First Mate. She sure gets around. What a pic.

I have a Baja with the 454. It's the perfect boat for us. New Marine 454's are around 5500. Jacked up they are closer to 8k. That might be high performance ones in the donzi. I know why he's changing motors .....SPEED. Somebody is beating him and he wants to put an end to that. :)
If the wife hadn't talked some sense into me I would have been running dual motors in a 30' baja ....but that didn't happen. :( ...probably for the better.
Kinda cold for doing a real test run with the motors in the donzi.
I wondered if you'd need all new merccruiser lower units. If you did that would sure raise the price considerably. probably be a deal breaker.
 

Chief

New member
That question crossed my mind as well. I would have thought the boat would be winterized by now. I would be very leary of buy the engines as is. Winterizing was a pain in the ass but very cheap insurance. Took me about 25 gallons of pink antifreeze and a quart of oil to get everything done, not to mention the cleaning and stowing.
 

Wannafish

Floppy Member
SUPER Site Supporter
Boat is inside a heated building as he is getting ready to pull them.

No outdrives for me - will be mating to my "Velvet" v-drives (Inboard).

He claims the engines are the 330 hp version. He wanted to go with the 604 Merlins but his wifey said "NO.":StickOutT
 

waybomb

Well-known member
GOLD Site Supporter
3000 is not bad if they run with oil presure at temperature, and no noises. 250 hours is usually the limit on a go-fast engine; after that, things start to break. Especially valve train stuff.

I would then disassemble them, valve jobs with new inconel exhaust valves
( do not try to save money here - it will cost you in the long run if you use regular exhaust valves), new valve springs, new rings, bearings, and oil pump, assuming you do not need a re-bore. Get the valve jobs done at an engine shop that specializes in high performance marine engines only. Make sure the valve spring installation is dead nuts on spec. Most automotive machine shops just don't get it. They build great street engines, but simply don't understand the loads put on a marine engine.

While you are at it, new plugs, filters, cap, rotor, and carb rebuilds. And if you want to spend a bit more money, dynamically balance the rotating assembly - it will add years to the engine (with everything else being equal), it will have better throttle response, and will run smoother.

Make sure your shafts can handle the extra horsepower, or you will twist them. You have choices with shaft material - it may be cheaper to buy a stronger shaft instead of a larger shaft, shaft log, strut, etc. More horsepower also requires a prop change - but you can find those cheap on eBay all the time, and you can sell your there too. You can probably also sell your old engines on eBay too.

And you'll burn more gas - at WOT, figure 1/2 pound of fuel for every horsepower. Two 330 horse engines will burn about 330 pounds of fuel, or about 50 gallons an hour at WOT. If your old engines were 250 horse each, you'll have 80 horse more per engine, or 80 pounds of fuel burn more per hour than before, or about 12 gallons more per hour at WOT. At cruise, probably about 10 gallons an hour. But of course, you will get to where you are going faster, and I bet net total fuel burn for a given trip at max cruise wiil be about the same with each combo, but you'll have more time at your destination.

Good Luck!
 

Dargo

Like a bad penny...
GOLD Site Supporter
I repowered an 1979 CVX-18 Glastron Carlson from a 305 to a 454. Here is what the boat looked like http://www.classicglastron.com/79gl-carlson-cvx18.html
You can now find that 454 engine, along with the outdrive, 1.1 nautical miles upstream from the "Dogtown" boat ramp in the Ohio River at a depth of about 32'. Going to the 454 and using a 2 bladed 28" pitch prop was getting me close to 80 mph. That was right up until the point I flipped it over backwards. The boat landed upside down and backwards at an estimated speed of 70 mph. It pretty well exploded on impact. Hitting the water at that speed for me was so violent that I actually let go of the beer that was in my left hand. :eek: My girlfriend at the time never went out with me again (actually a good thing). My boating days were pretty well numbered after that. I broke 6 ribs and somehow had an eardrum rupture. My lady friend ended up with a broken foot; dunno how.

I'm not trying to discourage any speed, just reading about adding a 454 to a boat reminded me of this incident. The Coast Guard write up described my boat as "grossly overpowered". Maybe it was a wee bit so for an 18' boat. :D It sure was a blast, right up to the point it nearly killed me.

Most of the important questions have already been addressed. The only other one I'd mention would be to take a flashlight and mirror to check the sides of the blocks for any possible freeze damage. I've actually changed the engine in about 5 or 6 boats. I got screwed one time because once I got the engine out of the boat it was in, I found a nice big bulge in the block from freeze damage. Yes, it promptly blew out on my first outing. I should not have put it in after seeing the problem. Oh well, live and learn. Good luck!

The above incident is why I've been quiet on the boating stuff here. For almost 14 years I boated about 40 to 50 times a year. With our season where I live, that was about 3 times a week! I even worked on a paddle wheeler that did cruises and had a Limited Master 100 Gross Ton license. That sounds impressive, but it is about the smallest license in the class of Great Lakes / River licenses. I had to get that when the "real" captain was so drunk that he rammed the dock and nearly sank the thing once. :drink:
 

Wannafish

Floppy Member
SUPER Site Supporter
Holy Sh1t - got me beat :tiphat:

These engines will be going in a whale - 36' Trojan Tri-Cabin. They might let me get all the way up to 35 knots!
 
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