Will A Truck Engine Work??

[CDAHDAH]

Hey guys, I've previously posted a thread on water issues with the my engine with regards to me finding water inside my cylinders. Long story short, I have to replace the engine due to water sitting in the cylinders for so long that the piston rings have rusted so bad that im getting a horrible compression ratio.

My buddy/mechanic mentioned to me that he can replace my 85 marine GM 350 engine with a truck engine, 350 but a later model (most likely late 80's).

I'm a bit skeptical about replacing a "marine" engine with an automobile engine. I know we use lower rpms and a different torque ratios when we tow, but not sure to what extent this makes a difference.

Is this a very stupid thing to do or is it common to swap a stock Supra engine with an automobile engine? The reason I'm doing this is I was told I could get the whole engine (minus carb and accessories) for about $500. That's A LOT cheaper than rebuilding my own engine.


Thanks guys,

CD

[1098miller]

Wouldn't do it. Marine engines are typically built a lot stronger to handle the constant delivery of power needed to move through water. In a car or truck, you are on and off the throttle and the engine can slow down on it's own as your transmission disengages. Boat engines are pretty tough for a reason, that's why they are usually more expensive to rebuild.

[iwakeboard]

Wouldn't do it. Marine engines are typically built a lot stronger to handle the constant delivery of power needed to move through water. In a car or truck, you are on and off the throttle and the engine can slow down on it's own as your transmission disengages. Boat engines are pretty tough for a reason, that's why they are usually more expensive to rebuild.


I'm pretty sure that alot of boat engines, particularly older ones, are simply car/truck engines mounted with USCG solenoids and other minute stuff like that changed. I know my '86 Glassport that I used to own had a 4 cylinder Chevy engine with a 2 barrel rochester carb on it, easy as cake to fix, get parts for, and work on. The drive shaft simply enters something different than a traditional drive train (i.e. a lower unit on an I/O).

[michael hunter]

They all start out as auto engines the marinizer adds the marine add ons [freeze plugs,starter,fuel pump ext. The cam is changed to reverse the running direction. As long as all the marine parts will fit and the engine is good you should be fine.
http://www.glen-l.com/weblettr/webletters-7/wl56-marinizing-1.html

[beast 496]

Hold on and wait a minute. First off, Marine engines are a little different. In the Marine engine you will find a much stronger crank, and a different grind cam. The cam is the most critical part. The heads are also different sized combustion chamber and valve size. The intake is also diffent but can be swaped over easily. Must use Marine ignition, fuel and electrical systems. The Marine block is generally in the industrial division of GM. It can be done but remember these engines are capable of running WOT all of the time, when was the last time you drove a car or truck at 4000 to 4500 rpm all day long? Is the cam in good condition on your damaged engine? is so swap out with new lifters. How about the heads? What style are the pistons on your replacement motor? What is the compression ratio on the replacement engine? All of these combinations can effect the reliability of your new motor. You mentioned your boat is an 85 not many Supras were made with GM engines in 85 most were Fords PCM 351. Unless you had a big block which was the 454 PCM Al

[CDAHDAH]

Thanks for the input guys.

Beast, I'll try to figure out exactly what model the new GM 350 is. From what I understand, Supra made special editions and put 350s somewhere around the mid 80s.
Will a cam on a 1985 marine GM350 fit pretty much any GM 350 in the 80s??
Not sure what the aesthetically everything looks good, but for some reason it was just leaking water into the cylinders and i don't know how. Im gonna get the heads checked to make sure, but i have a feeling their somewhat warped. Nothing else makes sense why water is getting in the cylinders.

As far as rust prevention, do marine engines have a special coating of some sort that resists water more than an auto engine? It totally makes sense about the torque/rpm and how they differ from auto engines. But you think it'll work out if I swap the cam/lifters and possibly the heads if their good??

[docdrs]

Beast is exactly right, way diff cams and these engines are designed to have the sh*t kicked out of them all day long, I barefoot and we run idle to wot or close to it constantly with out a prob. do that with your car/truck and seee how long it lasts

www.michiganmotorz.com

[beast 496]

If you are going to swap the cams verify the cam brgs are good. The cams are interchangable. Have you checked at some local machine shops on rebuilding your original engine? Price should be around 2k for a complete rebuild, as long as nothing is cracked. Al

[zalamander]

Short and sweet answer would be "YES"
I had a '82 Mastercraft S&S that had the engine replaced prior to me buying it. I found out when I removed a bolt and found the block was originally blue (ford) PCM blocks are factory silver (at least old ones that I know of). As long as you use all of the "marine" based stuff from your old engine (ie. carb, dist., alt, etc.) you will be fine. In the 4-5 seasons that I had her I put over 750 hrs on it and a lot of that was surfing, which abuses engines because you never plane out, kinda like a tractor pull contest. Just make sure you get a good engine, if you can find one out of an older truck or camero that hasn't been abused it should work fine.
Just to clarify... I'm not trying to argue anyone, but I know for a fact that if you have a blown engine and very little ca$h, you can make a good street engine work in your boat.
Whatever you decide, good luck, and happy floatin!

[zalamander]

As far as rust prevention, do marine engines have a special coating of some sort that resists water more than an auto engine? It totally makes sense about the torque/rpm and how they differ from auto engines. But you think it'll work out if I swap the cam/lifters and possibly the heads if their good??

From my understanding the marine engines are cast with a higher nickel content in them to help prevent rusting issues... as far as water in cylinders, hopefully your head gasket is is just bad. If you have warped heads you can usually have them resurfaced for a reasonable price. If the head is cracked (still better then block cracked) you will want to look into getting new ones. I would stick with marine heads.

Still... truck engine = not as great as original engine, but you'll be up and running.

[vvfdfirefighter]

Does anyone know what the compression ratio on an 87 Supra Marauder with a PCM 454 CI should be????