re-power CC Roamer Offshore (38ft)

Ignition timing

Chrysler Marine Maintenance Manual calls for timing to be set at 5 degrees BTDC for the M-413 Marine Engine. Distributor RPM Advance at 0@300 to 400; 0 to 4.5@400; 11 to 13@700. Maybe check with your mechanic on his specs.

Now We're getting somewhere. Laurence, Your specs are for an M413 Chrysler setup, with FACTORY Distributor and camshaft, which means factory calibrated advance wheights, springs and predicted advance curve.

Once You replace the factory distributor, You'd better know what Your'e doing, knock sensors or not.

This is why the "Total Timing" method works for any application, knowing and then limiting the highest amount of advance keeps Your motor from burning down while still giving You advantage and benifits of the engine upgrades above 2000 rpms which is where most mechanical Distributors are full opened up and advanced. You may suffer slightly on the bottom end but You wont be needing a new motor.

An electronic Distributor still has an advance curve, it's in the module, some are even programmable for the advance curve.

If Offshore Really wanted to get to the bottom of this it would be simple to do. As the evidence is in the other motor that still runs, ASSuming that they were tuned similarly. Put a timing light on the runing motor, free rev to 3000 rpm's and check the timing, no matter what kind of distributor it has, if it's in the high 40's btdc. . . . . . You have the smoking gun.


Kiwi

Not always, there is a third failure, over-revving an engine will snap a connecting rod. If the transmission (v-drive) came out of gear and the engine revved to the moon, you could snap connecting rod bolts or the connecting rod itself and the piston wouldn't have any detonation damage on it, maybe a meeting with the valves but no detonation related damage from over-revving.

A lean condition or too much timing would also cause damage like this, but you usually see it in more than 1 cylinder, and usually see a blown head gasket between two cylinders.......

Do you have pics of the engine with the heads off?

Also Chevy 350 cu inch rods are darn near bulletproof. I've seen people take them to almost 8000 rpm's with stock rods on a regular basis.

I suppose You could run them to "almost 8000 rpm" but I can't see that happening in a prop/engine loaded situation, as without a set of highly exotic ($$$) cylinder heads, even the Vortec head stops seeing any flow increase at about 5400rpm's, at which point mechanical friction increase would limit any increase in power for increased rpm. In other words anything over 5400 rpm's has no benefit.

I have noticed that Offshore never mentioned what size/brand motors We are talking about.

Kiwi

The motor in question is a Chrysler 440cu in marine application.

I have a feeling the transmission slipped allowing for a much higher rpm, or possibly the propellor became unloaded.....or it was just a weak rod or rod bolt, and the rod let go........But without seeing the motor, there's no way to say. Water intrusion into the cylinder while it was running would bend a rod also pretty easily........It could have a cracked cylinder liner as well from improper winterizing, that allowed water to leech into the cylinder.......or exhaust manifolds.......there are so many scenario's without being there, and taking it apart, it's tough to really say........I've also seen where a 350 chevy had a little bit of a cam put in it, and had the factory exhaust manifolds and risers and it was sucking water back in the exhaust because of the cam, and longer risers solved the issue.......

But too much timing and/or a lean condition could melt a piston and cause a connecting rod to let go, but the piston would tell the tale on that one.......

I was talking a 350 cu inch chevy's in street engine applications. I've seen lots of people take stock 350 cu in rods in balanced and blueprinted motors with solid lifter cams and good cylinder heads and spin them up to 8000 rpms on a regular basis and never have a rod issue.......The Chevy rods are very strong....Heck a lot of the early 350's back in 1969 in the SS camaro's and such.. had a factory redline of 7000 rpms, as opposed to Ford 460 rods and Chrysler 440 rods that are not considered strong or good enough for 6000rpms......Strong enough for normal use and hp they were designed for, but not when building an engine with a lot more hp.

Move to Milwaukie

If you still have one engine, why do you need the tow?

Hi,

Having had one engine throw a leg outta bed for an as yet unknown reason the OP is probably being justifiably cautious.

If he has paid for a service already them why not use it if it suits?

I had a a Offshore repowerd, with Ford 6cyl blocks and marinades by Renault diesel they were 160 hp turbocharged and after cooled. I loved them but couldn't get spare parts, even from Renault. I also had a friend who had a Offshore with Detroit relined diesels. If you like to get more info from e-mail me with questions.
Heide163@aol.com

Hi,

Have you looked at these guys?

http://remanufactured.com/Inboard_Marine_Engines.htm

Engine options

I would check with these people instead:
http://www.daddyosmarine.com/

I've been there and seen how they rebuild motors and have customers that have bought them. Steer clear.

I have never seen good things happen with remanned engines. We did 12-15 engine change outs or gas to diesel conversions a season and brand new is the only way to go if you can justify the expense. You can get by with the old gears and v-drives. I would change out the seals and stuffing box hoses while you can get to them. By the time a gas engine needs rebuilt in a boat, corrosion has usually worn out everything on it. I burnt up a brand new mercruiser long block by using the old fuel pump. I figured out too late that is what caused the first engine failure. Gas leaked in the block, diluted the oil and that was the end. The first engine had low hours so I never thought twice about it.
The main difference in a counter rotation is replacing the timing chain with a timing gear on the cam and crank.

Hi,

You might want to start here: http://www.dieseldoctor.com/messageboard/data/803.html

Then go here: http://www.expertdiesel.com/82_detroit.htm

Here is the story of a couple of them right here on YF: http://www.yachtforums.com/forums/chris-craft-roamer-discussion/12598-whole-story-6.html from Post 89 onwards.

Hi,

No personal experience with them myself but I looked at what he said about the 8.2's and thought it to be a very detailed description of the process.

If this is how he works in practice I would say he would have as good a chance as anyone in re building an 8.2 that would last.