difference between outo engine and marine engine?

[szyska]

is ther a difference?i have a cracked block and would like to swap the complete boat motor with a 4.3 gm from a truck is this possible?

 

[Liljoe]

Re: difference between outo engine and marine engine?

With our 165hp (250 block) the difference was the mounting holes were on the front and not the side of the block. Had to search for one. Then the freeze plugs needed changed to brass. Then all the parts from the old engine went on. Just look at how the 3.3 is mounted in the boat and see if it is mounted the same.

 

[Navigator]

Re: difference between outo engine and marine engine?

There are some 'major' differences between Auto and Marine engines There was a discussion about 2 months back on this exact topic and why they shouldn't be swapped.. You may want to search the archives.<br /><br />Some of the major differences are <br />+ different Cam Shafts <br />+ structurally stronger parts in the Marine engine.<br />+ Cooling system is usually different<br />+ Carbs / EFI systems are different due to different torque curves<br />+ Block is stronger in a marine Engine.<br /><br />As to your question, you probably could swap an old truck engine with your dead marine engine, but would you be satisfied with poor performance and horrible reliability? Your call.<br />Now if you're going to swap all the componants like Liljoe mentioned, then maybe it would a bit more cost effective..

<br />Sounds like an interesting way to spend the summer.<br /><br />Sorry, I didn't mean to rain on your parade, but it would be really sad to have you go through all the work just to have the engine break down on you in a short while.<br /><br />Nav.

 

[Navigator]

Re: difference between outo engine and marine engine?

Sorry,<br />Look in the Engine forum archives for that discussion. I dont think it was in the Boating forum.<br /><br />Nav.

 

[szyska]

Re: difference between outo engine and marine engine?

thanks for your comments and wisdom .... a new marine block it is. thank you again.<br /><br /> SZYSKA

 

[phillnjack]

Re: difference between outo engine and marine engine?

you guys dont seem to know much about inboard engines at all. a 4.3 block is a 4.3 block. ther is no such thing as a marine engine unless you go to real big stuff or outboards. auto engines are marinised , in otherwords they have the ancillaries changed . ie exhaust manifolds.water pump, core plugs, sometimes an heat exchanger. as to efi well that depends on the power curve your looking for but a truck engine block is ok just think to yourself if it got enough torque for a truck then its fine for marine use just play with the prop to get right.

 

[ThomWV]

Re: difference between outo engine and marine engine?

Phillnjack is right on the money. The basic short block is exactly the same, with one exception, and not even that with good rebuilds. The "Marine" engines won't use aluminum freeze plugs, they will be bronze. But then a lot of automotive rebuilders use bronze ones anyway. If you had a GM 5.7 liter (350 Chevy) engine you'd want to find one from a truck. You might wonder how in hell you could tell if it was just one in a pile at the local junk yard. The difference is that the truck engines had 4-bolt main bearing webs, the car engines didn't, and the junk yards know it and keep them separate. As far as the cam's go, yes, the marine engine companys will put in a cam that is designed for lower end power production but here's a hint for you, just go to any of those chain auto parts places that sells aftermarket cams (a lot of Eldebrock stuff sold this way) and pick up one for RV engines. Exactly the same cams and very inexpensive. Of course the mounting is particular to the boat but they all use the standard automotive holes in the blocks. The exhaust is as different as day and night but it all bolts right up to the standard automotive heads - because there is not a single marine engine builder in existance big enough to cast and machine their own heads. When it comes to intake boats use archaic systems in comparison to the controls used in todays boats. Know how you can tell? Easy, your boat doesn't have a half a dozen black box computers mounted all over the place in hidden little cubby holes.<br /><br />Thom

 

[Ralph 123]

Re: difference between outo engine and marine engine?

szyska - go to amazon.com and search for the book "small block Chevy marine performance" by Moore and read the free excerpt there. It discusses in great detail all of the differences between a marine engine and an auto engine. In general, it is a great classic book to own.

 

[Bondo]

Re: difference between outo engine and marine engine?

i have a cracked block and would like to swap the complete boat motor with a 4.3 gm from a truck is this possible?

Without a Doubt.... It's the best answer.....<br />phillnjack + Ralph are Right on the Money....<br />ThomWV, automotive freezeplugs are Steel....BTW, Standard Mercruiser Engine blocks are 2-bolt Blocks.....(but ya, 4-bolts are Desireable)<br />"+ Carbs / EFI systems are different due to different torque curves"......<br />That's ancillaries, not the block....<br />"+ different Cam Shafts".....<br />Not Really, Well Maybe, a little bit.....<br />"+ Cooling system is usually different"....<br />Not for what we're talking about....<br />"+ structurally stronger parts in the Marine engine"<br />"+ Block is stronger in a marine Engine"...<br />Just Not So....<br /><br />A GM Goodwrench block, change the freezeplugs to brass,+ Reinstall with the ancillaries from the motor you have now........<br />I think those GM shortblocks are around $1200. or so.....

 

[BillP]

Re: difference between outo engine and marine engine?

Every gas inboard I've seen was a marinized auto engine (Palmer, Gray, ChrisCraft, Daytona, Merc,etc)OR some type of farm machinery conversion (25hp Gray Lugger 4-91 = Continential Y91 = tractor engine). NAPA stores always seem to know the marine match for auto parts. <br /><br />Double check the head gaskets if is marinized though, because the head is tapped to dump cooling water downstrean of the exhaust elbow, etc. Car head gaskets don't always have the same water holes punched (on a 4 cyl 60 hp Chris Craft engine anyway...found that out after a rebuild on first start up. It wasn't easy to figure out either. These small differences can ruin your day.

 

[RainMan302v8]

Re: difference between outo engine and marine engine?

When I "marinized" the 302, I did the following, but only because I was using Raw Water, Fresh Water Cooled engines use antifreeze like cars do, and truly the difference between them and car engines is the little more than a cam grind<br /><br />If you are going with Raw Water, and plan to operate on salt water, swap out your steel freeze outs with brass plugs, and install stainless steel head gaskets and intake gaskets <br /><br />now would be an excellent time to never seize every bolt, nut and stud you can unscrew, saves hassle down the road<br /><br />Hope this helps

 

[Bondo]

Re: difference between outo engine and marine engine?

BillP,<br />With some of the more obscure engines, you may be right....<br />For the sake of This Thread, Standard Production Chevy based Marine engines have the Same headgaskets.... Steel shim gaskets are Rarely used these days... They're all using the Composite gaskets.....<br />No Difference......<br /><br />To clerify my previous post,<br />szyska, <br />You'll have to find an engine from the same Vintage to do your swap... There are several changes to the 4.3l blocks, from the beginning till now.....

 

[BillP]

Re: difference between outo engine and marine engine?

Bondo, you are right. It was a long time ago but I will never substitute marine for auto parts again without checking all the head gasket holes. Everyone told me the non marine parts for a ChrisCraft were the same too...with exception to the head gasket they were.