Engine rebuild/swap

[Lucenut]

OK, so I have a cracked block in my 1984 PCM 350. The boat started and ran smooth but water was pissing out a 3" crack on the port side of the engine about an inch and a half below the head gasket. I shut it down after about 5 minutes of running on the trailer at the boat ramp and took it home. I rounded up a guy to weld it, but when I went in to take the strainer basket and a couple of the spark plugs out to prep for repair I noticed a good bit of milky oil in the bilge. I didn't notice it when I had it in the water the day before, and I'm pretty sure I would have.

Now I have friends telling me it's toast because their obviously is an internal crack/leak also. I can't find anywhere oily on the engine where it leaked out. The oil on the dipstick is a bit milky also. :-(

Was perusing the internet/craigslist for a replacement, and noticed a nice circa 1970 350 ready to go for $900, but with a completely different firing order than what mine says on the PCM tag on the intake manifold. Are all PCMs a different firing order? What is the purpose of that?

I guess I was hoping to find a complete engine that I could swap in and just bolt up my water pump, alternator, carburetor... and exhaust manifolds and go. Can anyone tell me what you run into trying to replace a marine engine with a street engine? I could get a short block and swap in my cam right? Then bolt on everything else from my old motor?

Advice on getting this thing back in action rapidly, at a decent cost for a non-mechanic? :-)

[t.franscioni]

The block you have is an automotive block there is nothing marine specific about the block itself. The cam is marine specific and the freeze plugs are also. Any good engine rebuilder/machine shop can strip all your marine specific components off your cracked block and Bolt them up to a replacement block and help you identify what block you have and where to get a replacement. An engine rebuilder will likely suggest other things like a valve job, all new gaskets for sure, decking, pistons/rings, crank cam bearings, lifters, valve guides, cylinder honing if the replacement block is used.... getting back on the water quickly might be a stretch unless you can find the correct engine ready to go.... The 1970 350 your looking at is probably a different rotation and or model than your 1980s 350 and therefore won't work with your components.

[surroundsound64]

Hey! Another Chevy boat owner! My 1981 SN has a 350 in it. The firing order is due to a gear driven cam shaft instead of a chain drive like you find in the automotive applications. Other than that, it's pretty much the same except for the marine specific parts.

[Lucenut]

Do you guys think this engine would be a suitable replacement? I could bolt on my exhaust manifolds. What about the rear of the block do I need to worry about? Will most engines bolt up to the existing transmission?

http://lacrosse.craigslist.org/bpo/5616126947.html

[Quinner]

One key factor not mentioned is if that is the original engine it is almost certainly reverse rotation (right hand). You really want to keep the rotation the same if going with a replacement. Are you also sure it's a Chevy 350 and not a Ford 351? 350's were available but probably 95% came from the factory with 351's. If you get the existing motor rebuilt I would recommend using someone with Reverse Rotation experience, there are some very specific differences in gaskets, assembly, etc. required for a RR motor.
Good luck!

[t.franscioni]

Someone with more knowledge of your era boat/engine will have the best advice as too whether or not that replacement will work. If it was me I would just find the block you have at an online auto parts store or junk yard and have an engine builder put it all together. It will cost more than $1000 though if you have an engine builder do everything. I had an engine machine shop just do the machining on my block and heads and the basic assembly then picked it up as a long block painted and ready to go. That cost me $1600 then I did all the rest of the work myself which saved a lot of money. Sounds like your boat is just a tool to have fun and enjoy the lake (as it should be) and you just want to get back on the water quickly. In that case this replacement your looking at might be the way to go for you. You might run into some issues utilizing your dash gauges and connecting them to this new motor without some wiring changes. Also engine mounting issues that will require some fabrication perhaps...

[Lucenut]

One key factor not mentioned is if that is the original engine it is almost certainly reverse rotation (right hand). You really want to keep the rotation the same if going with a replacement. Are you also sure it's a Chevy 350 and not a Ford 351? 350's were available but probably 95% came from the factory with 351's. If you get the existing motor rebuilt I would recommend using someone with Reverse Rotation experience, there are some very specific differences in gaskets, assembly, etc. required for a RR motor.
Good luck!

Great point! I forgot about that. Is right hand rotation different than street GM 350s? I guess I thought it was the transmission that made the prop rotate RH or LH. They really run the motor in the opposite direction?

[Quinner]

Through 1988 almost all direct drive CC's were right hand props, the 1:1 trans used through 1988 needed to run the same direction as the motor therefore the motors were RR, so yes your boat was originally equipped with a reverse rotation engine. In 1989 the 1:23 trans was introduced, that trans could counter rotate the motor, hence lefty motor with a righty prop for 1989+ CC's.

As previously mentioned, you really want to use a re-builder with RR experience or you may end up with issues. If you are trying to do more yourself or seek referrals for a re-builder try also posting on CCFan, there is a wealth of old school knowledge over there and several guys who live north of the cheddar curtain like you.

[DLafont]

I was just going to chime in on CCFan, but Quinner beat me to it. They're really keen on the older boats over there, so I'm sure they'll be able to guide even better than we could here.(at least me...)

[gary s]

Another thing to check is rear main seals, engine blocks with that many years between them could have important improvements done to them that are not externally seen. Fords which I have more experience on,went from a 2 piece rope seal to a 2 piece rubber seal then to a one piece seal on the crank in those years. The last change was a different block casting and is not backwards compatible seal interchange wise. You'd have to check with someone with GM experience and get their thoughts.