Truck Engine in a Boat??????

[petes penn]

So my engine is toast.....rally toast. I have searched and found that several are using GM 350's from trucks. Has anyone had any luck or horror stories with these engines? Just want to get some input before I purchase one.

Thanks in advance.

 

[mkast]

Re: Truck Engine in a Boat??????

You can put anything you to in your boat, barring insurance and USCG.
There, you're off the hook.
You can now say, "I heard".
Do a search, people who know what they are doing can make this swap without killing someone.
If you are asking, I suggest , "DON'T DO IT".

 

[Maclin]

Re: Truck Engine in a Boat??????

If you have a GM 350 in your boat already and are just needing to replace/repower then in most cases the blocks, heads, etc are the same as a "truck" 350. There are a few components to change over and Marine-ize it. The "truck engine" is usually used because Marine and Truck/RV cams are in principal the same, and the load requirements are similar.

Some things to Marine-ize or swap in from whatever you are replacing....:

Core plugs, use brass.
Use the intake and carb from the Marine engine.
Use the engine water recirculating pump from the Marine engine or buy new Marine version.
Use the alternator and starter from the Marine engine or buy new Marine versions.
Use the ignition system (distributor, etc...) from the Marine engine.
Follow the Marine engine specs for spark plugs and thermostat.
Some would change the head gaskets to stainless steel core.
Should replace the exhaust manifolds and risers at this time.

 

[Fishermark]

Re: Truck Engine in a Boat??????

Don't know what year you are dealing with - one piece main - vs - two piece, etc.... But this deal is hard to beat:

http://www.gmpartsdirect.com/results.cfm?singlepart=1&partnumber=10067353

It is a crate engine direct from GM - part# 10067353 It is the universal 350 which is a basic brand new 4 bolt main truck engine straight from the factory. Take all of your accessories and intake off the old engine and put them on the new. Shop around and you can usually find one for $1,300 or so. Here's a pic:

 

[Uraijit]

Re: Truck Engine in a Boat??????

That's the exact engine I found in a salvage yard for $100.

Get a salvage yard block, go through it. Maybe freshen it up with some new rings. All told I put $186 into buying that long block from the salvage yard, replacing every gasket on the thing (including head gaskets), new brass freeze plugs, and a fresh set of rings.

Ended up spending another $20 on a new set of head bolts, after my wife broke one while learning how to torque, and $13 on another head gasket.

If I'd been thinking, I would have just taken a bolt off my old block that I was replacing...

My $200 engine is a totally solid and awesome engine! It's got more power than the stock Mercruiser that was in it before. And it cost about 1/10th the cost of buying a reman from someone else.

Now if the rest of the boat were as solid as that long block...

 

[petes penn]

Re: Truck Engine in a Boat??????

As I stated in a previous post, I contacted my local salvage guy. He has 5 long blocks in running condition in stock right now for $300 each.

As I am new to this, could someone explaint he difference between auto intakes and marine intakes?

I half removed my starter, water pump, alternator, and carb. The carb I am going to replace as the electronic choke was not functioning and the butterflies were a little stiff. The boat will be entirely re-wired with new as the old is 33 years of age and there seems to be some hokey looking splices and capped off wires hanging in the bilge. I figure replacing it all will lessen the fire hazard potential.

Is there anything else I should be aware of?

Thanks again to all that have aided me.:redface:

 

[JustJason]

Re: Truck Engine in a Boat??????

As I am new to this, could someone explaint he difference between auto intakes and marine intakes?

the biggest difference is the water passages are brass or bronze lined to help slow down saltwater corrosion.

 

[petes penn]

Re: Truck Engine in a Boat??????

Some pictures for your entertainment:

Nice crusty manifold...........time for a new one.........

http://i31.photobucket.com/albums/c383/picasso928/Boat/DSCF1965.jpg

exhaust ports.........ewwwwwwwww not pretty

http://i31.photobucket.com/albums/c383/picasso928/Boat/CopyofDSCF1959.jpg
http://i31.photobucket.com/albums/c383/picasso928/Boat/CopyofDSCF1960.jpg
http://i31.photobucket.com/albums/c383/picasso928/Boat/CopyofDSCF1961.jpg

before.....

http://i31.photobucket.com/albums/c383/picasso928/Boat/CopyofDSCF1834.jpg

after.......

http://i31.photobucket.com/albums/c383/picasso928/Boat/DSCF1964.jpg


laughing/cringing yet?????

 

[Fishermark]

Re: Truck Engine in a Boat??????

It doesn't have to be a marine head gasket. Fel Pro makes a composite gasket that works great.

 

[Uraijit]

Re: Truck Engine in a Boat??????

Questions, you were able to have the block honed and replaced all the gaskets for $86? Man that is one cheap machine shop!!! And, where do you buy a marine head gasket for $13?

The cylinders still had cross-hatching in 'em. I went ahead and honed it anyway. You don't need a machine shop to hone your cylinders.

If you're going to be getting it BORED, then yes, it's machine shop time. As well as time to put in new pistons.

Fel-Pro makes a GREAT "Marine" head gasket.

You can get a whole gasket set for $40 here http://store.summitracing.com/partd...889107+4294925237+4294925236+115&autoview=sku

Word of caution though, that block is drilled for the dipstick on either side. The oil pan comes with two dipstick "humps" so the dipstick can be used on either side. The oil-pan gasket that comes with this gasket set just has a straight shot on one side, so it leaves a gap under the pan "hump". You'll either have to plop down $11 for a different oil pan gasket, or use a little silicone to seal up the gap...

 

[petes penn]

Re: Truck Engine in a Boat??????

I forgot to include my compression test results....this will make you really laugh....

1. 100 psi
2. 85 psi
3. 70 psi
4. 90 psi
5. 65 psi
6. 80 psi
7. 75 psi
8. 80 psi

Pretty bad and justifies replacement. Uraijit.......I'm going your route as I am mildly mecjanically inclined and my wonderfull brother (vastly superior in the mechanics field) has been there to help me all the way. So, we're gonna keep it and make her better than what she is now.

Here is a link to the album pictures regarding the progress so far. I will be sure to update when new come. Are those risers/manifolds supposed to look like that?

http://s31.photobucket.com/albums/c383/picasso928/Boat/

 

[FreeBeeTony]

Re: Truck Engine in a Boat??????

The person you bought this from said it was running?

 

[hard-3]

Re: Truck Engine in a Boat??????

When you get it out and torn apart, do your self a big favor and take it to the machine shop and have it checked out. cylinder roundness cannot be seen by looking at it. needs to be measured with precision equipment to verify roundness of bore. A cylinder bore with wear can look ok enough to ring and reassemble, but if its out of round then you will have a hard time getting it to seal . Honeing with a whirleygig hone will re-establish a good cross-hatch on the cyl wall but can still be egg shaped. Have it checked and ridged honed. you might be cheaper to replace the heads with remanned ones, just make sure they are same castings and ok for marine use. Old chevy heads were made with cast iron valve seats and don't work well with unleaded gas. Later model heads have diferent valve seats to hold up. Measuring also make sure every thing is still standard sized. Some engines come from the factory as odd-sized. Once had a 460 ford with 1 piston bored .020 over from engine factory. Even though you may have owned it since it was new does not mean it was not remanufactured new when it was first assembled. watch out for some of those low-buck engine kits also. they have sub-standard parts that may not have the life span or the ability to hold up to sustained rpms found in a marine engine. Spend a little more for quality rebuild parts and you will be happy in long run. rebuilding your own engine is not hard to do if you can read and follow the instructions from the service manual . As I stated in the first line take the Block to a good machine shop and have them check it out for you. It will be money well spent.

 

[FreeBeeTony]

Re: Truck Engine in a Boat??????

I wouldn't bother rebuilding it............

Get a longblock, new manifolds/risers/starter/carb/etc...........you can have a new engine for <$3K if you can afford it..........

You are going to need to replace the manifolds/risers anyway........don't think you are going to save that much $$$ by rebuilding the existing block/heads.

Just my $0.02...........

 

[Uraijit]

Re: Truck Engine in a Boat??????

So you were able to tell that the cylinders were not out of round or "bell shaped" without a machine shop? Thats pretty amazing. I agree, with a decent set up you can hone a cylinder (a good drill press to make certain you are wearing evenly) but if you are talking about one of those cheap hones to go in a hand drill, forget it. There is no way to keep them perfectly centered or applying the same force on all contact points.

Aye, well then this is REALLY going to blow your mind. It's called a "cylinder bore gauge set" You can get a set of bore gauges for under $50.

What do you think machine shops use? What do you reckon they did 40 years ago, before all this digital measurement stuff came out? It ain't rocket science.

Oh, and did I mention that the cylinders were STILL CROSS-HATCHED!

Sorry but these are not marine gaskets and it WILL come cack to bite you at some point.

You're correct in that they don't come in a "Marine" package. But they ARE the same gaskets. The only gaskets in that set that I would advise not using would be those metallic exhaust manifold gaskets.

There's nothing magical about a "marine" gasket. Head gaskets just can't have steel in them. The rest of the gaskets are the same.

If these cheap gaskets did the job properly why do you think anyone (Boat builders) bothers making or using the right gaskets?

Who says they aren't using the same gaskets? If you could take a gasket out of a warehouse, put it in a different package with a "marine" stamp on it, and charge 3-5 times what it would sell for as an automotive part, why not? Clearly there are enough suckers out there to fall for it.

Hell, generic mustard is packaged in the same plants as brand-name mustard. It's the exact same stuff, in a different bottle. Same goes for a lot of spray paints, oils, dish soaps, lawn care products, and--you guessed it--GASKETS!

Do you have to have the "Frenches" label on your mustard, or will the same stuff in a different bottle do just as well to moisten your hot dog?

Hey, if you want to take the risk fine, but please don't advise others to try it.

If you want to pay through the nose for some "snake oil", then by all means, go for it. I, however, am going to help people avoid being taken for a ride at the marina parts counter! You may chose to take the help, or reject it and continue wasting your money. Your choice!

 

[wca_tim]

Re: Truck Engine in a Boat??????

couple points:

if you go with a marine long block, you will get a warranty...

If there is any doubt about your manifolds and risers, i would replace them rather than do the engine again in a few weeks,

a marine engine that is run much, is pushed a LOT harder than a car engine (think about running your car up a hill all afternoon - in 1st gear pulling a sled of logs). longevity is going to be an issue if tolerances are all over the map.

ON intake manifold water passages, most people just run car aluminum intakes or marine cast, not a huge issue as long as you're flushing...

gaskets are an issue... don't listen to anyone that tells you to use a car gasket... galvanic corrosion... you're talking a few bucks - why take a chance.

It invariably boils down to whether your time sand piece ov mind are more important than your money. I realize it is a balance, but I think the time and piece of mind you get from a new / reman longblock is easily worth a couple of long paddles, ruined time out on the water, major headaches, and the fact that you have to spend a bunch of time monkeying around trying to get old crap that may or may not be in spec and servicable... to work.

just my two cents...

 

[Fishermark]

Re: Truck Engine in a Boat??????

Uh huh,,, riiiiight....

Yep.

gaskets are an issue... don't listen to anyone that tells you to use a car gasket... galvanic corrosion...

I was going to leave it alone... but since it has been brought up a couple of times already....

Galvanic action? Did you note I mentioned / suggested using the composite gaskets? These are head gaskets with no steel in them. You only need to worry about galvanic action with dissimilar metals - not composite materials.

It invariably boils down to whether your time sand piece ov mind are more important than your money.

Couldn't agree more! If it gives you peace of mind to buy marine specific gaskets, go for it!

I realize they say "Ignorance is bliss" - Count me among the blissfully ignorant who believe there is a time and place to buy "marine" and a time where it is not necessary.

 

[Pimp Daddy]

Re: Truck Engine in a Boat??????

Don't wanna be a post hyjacker but can you use an automotive intake on a marine motor?

 

[Uraijit]

Re: Truck Engine in a Boat??????

Sure can.

 

[dan t.]

Re: Truck Engine in a Boat??????

if you are using a heat exchanger and running antifreeze in the block you can use any head gasket you want. the no steel rule only applys for raw water cooling. i have never bought a "marine" gasket except for exhaust manifolds in 15 years of saltwater boating . as for intake manifolds GM makes a special marine version but i think it would be a waste of money. a stock cast iron intake can be improved by machining out the devider between the primary and secondary holes on each side so you end up with 2 egg shaped holes under the carb .do not take out the center devider