What is "Rebuilt"

[RUSSELL]

I have a 1978 Catalina 30, hull #978. The boat has been maintained, but given her age she needs some care. I am about to embark on a drive train overhaul.

Following a lot of research and listening to others, I am led to Moyer Marine. I ordered, and have read, Don's overhaul manual.

My inclination is to remove my engine and swap with a MMI exchange engine. All of what Don talks about in the manual makes sense to me, except for one thing: replacement of parts and reconditioning as part of the overhaul.

I worked on cars incessantly as a teenager. We would pull an engine (goo american V8) and rebuild it. This means we would automatically bore the cylinders, grind the crank, put in new pistons, rings, wrist pins, rod and main beasrings, camshaft and bushings, valves, and so on and so forth. Every bearing was replaced; every surfaced machined.

It doesn't seem that MMI does that; or rather, they measure everything and do obly if past a judgment point in the tolerance range. That doesn't make sense to me - I would think it is automatic.

Anybody have any points of view they would like to share?

Russell

[ndutton]

Welcome to the group.

What's going on with your engine that indicates replacement?

[thatch]

"Rebuild Criteria"

Russell,
Welcome aboard. I own Catalina 30 #1039, which is also a 1978 model.
There are a couple of different schools of thought regarding "to rebuild or not to rebuild". Shortly after buying my boat a couple of years ago, I searched for and purchased another rebuildable A4. Like you, I came from a background of almost automatically pulling and rebuilding any engine that showed any appreciable signs of wear. Since then, after tinkering with the fuel system, the ignition system, and doing a Marvel Mystery Oil treatment on the engine, she runs like a top with good oil pressure and almost no blowby. My personal opinion is that, if you have a "Non seized" A4, it is worth a try to bring it back to life with a little TLC.
Tom

[ILikeRust]

If everything is within original specs and tolerances, with no unusual or odd wear, or scoring or other damage, I don't know why you would go to the trouble and expense of grinding and cutting away good metal.

The A4 is decidedly old tech. It seems to me, if anything, it's overbuilt, particularly given its relatively low compression. It's not a medical instrument or a Swiss watch, and I've seen examples (here and in real life) that look like hell but run just fine.

I just put my engine back together after a complete and total disassembly. I had a machinist friend come over with his bore gauges and mics and found the cylinder bores and crankshaft journals all to be within original specs. This is on a 28 year-old engine that evidently has not seen too many hours of use. Everything looked to be in excellent condition, and given that the measurements all came out to be where they should be (down to 0.001"), I saw no need to bore anything out or grind anything down.

I did have the head and block surface ground, to make a fresh, clean mating surface for the head gaskets, and I had the valve seats re-cut, because they got ground away with the surface grinding. I also lapped all the valves. That is the only machining I had done - I didn't see anything else as being necessary.

I of course replaced the rings, all bearings, valve springs and all gaskets.

I have no fear of the rebuilt engine not running beautifully for years to come.

What is the issue with yours that makes you think it needs to be replaced?

[hanleyclifford]

Especially in the matter of overboring cylinders caution is advised. Any metal you take away from the inside makes it that much easier for an intrusion from the water jacket side. IMO engines at .020" over are at the safety maximum unless you have new sleeves in which case you should be at standard.

[RUSSELL]

What is "Rebuilt" II

First, thanks for all of you who replied, and thanks for ignoring all of my typos.

Someone asked what was leading to the rebuild question. Here is the background:

I bought the boat in 2010; I think it has only been in fresh water on the Great Lakes: Huron, Superior, and now Erie. I bought her in Sandusky, Ohio and brought her across Lake Erie to Erie, PA. This was Memorial Day weekend, 2010. Oddly enough, the weather was sunny and beautiful but dead calm. Thus, we motored roughly 185 nautical miles in roughly forty hours.

Engine started and ran fine on the trip. I checked the oil before we left and after the trip - she used almost a quart. I did a compression check and found the following: cylinder 1 @110 psi, cylinder 2 @85 psi, cylinder 3 @115 psi, and cylinder 4 @110 psi.

Low compression on a cylinder and burning oil signals rebuild to my GM 350 cubic inch V8 experienced mind. I also think that a numebr of the updates I see MMI has (eletronic ignition, eletric fuel pump, aftermarket thermostat, etc.) make a lot of sense. So my initial reaction is to completely rebuild so I won't have any future problems to worry about.

On the other hand, after reviewing a number of your comments, I think it may make sense to pull the engine, break down into pieces, clean thoroughly, and check everything first.

Further thoughts?

Thanks.

[hanleyclifford]

Sounds like your A4 is in good hands and the guys on the forum will enjoy the rebuild as much as you. BTW, we love pictures

[Will Jacocks]

Probably just need to clean the valves, it runs pretty good so why mess with it too much?