difference between boat motor and car motor gm 350

[delsol]

hi whats the differences between a gm 350 marinr motor and a car or truck motor..i was told block is heavy duty like a truck motor cam. oil pump. gaskets . nopt counting bolt on's
if you run only in fresh water is it a must to get a marine motor
thank s bob
it may be a dumb question but

 

[Haut Medoc]

Re: difference between boat motor and car motor gm 350

Most notably, the cam & brass core plugs on marine applications ......
A GM truck engine would have a cam that was close enough for marine use.....JK

 

[MelLandry]

Re: difference between boat motor and car motor gm 350

I'm no expert, but I've been through this myself.

From the info I gathered, a 350 longblock truck motor is similar enough to the 350 marine to be interchangeable. The cam profiles are not exact, but they're similar. The true "marine" parts would have to be made for that purpose (carb, alt, fuel pump, etc.) and the "freeze plugs" would have to be changed to brass.

The cam profile on a car motor would put the RMP at max HP (hence WOT range) outside of the safe consistent operating range used in boating. The engine parts couldn't handle the high RMPS.

You'll also have to ensure you have the right replacement motor (2 piece rear main/1 peice).

Like I said... I'm no expert, but my boat has a 350 longblock truck crate motor in it, and I haven't had any problems yet.

 

[Buttanic]

Re: difference between boat motor and car motor gm 350

If you want as good or better than "marine" I would go to a 350 1 ton truck long block crate engine. These have all the heavy duty parts and a cam that is almost a duplicate of marine. If you run salt water and not closed cooled replace the core plugs with brass.

 

[imported_rosco]

Re: difference between boat motor and car motor gm 350

cam may have a differant profile, but that is just the tip of the iceburg.
1. anti corosion paint.
2. brass plugs in block where water jackets meet the heads.
3. special water pump with sealed berrings as opposed to automotive type that is lubricated by coolant.
4. brass or ceramic lined waterjacket in intake manifold.
5. brass freeze plugs.
6. as the other posters already indicated, almost all are the heavy duty versions with forged rods, forged pistons, steel cranks, and a cam geared to reach max power in the 3 to 4500 rpm range.
7. longer dipstick tube.

then you have the prehiperals.
1. marine distributer with spark arrestor so boat doesnt go boom.
2. alternator with spark arrestors so boat doesnt go boom.
3. marine carburator with brass sleeves on shaft and anticorosion coating.

you could by a high performance crate motor, replace the cam and freeze plugs, and paint it with anti corrosion paint and get away with it. its what the performance shops do as long as you have the other stuff already. it starts out as the same block, pistons, rods, crank as the heavy duty truck motors.

 

[delsol]

Re: difference between boat motor and car motor gm 350

rosco i am leaning towards truck motor or rebuiding this one. i have all the marine bolt ons on a frozen motor left 6 yrs sittilg..i live in phila pa and have all winter to get in done..89 glastron carlson css 19'
bob

 

[Darkhorse1201]

Re: difference between boat motor and car motor gm 350

As long as you use a like year motor you should be fine. I read your other post and know that you will be swapping over parts. Like the guys above said just change the core plugs. Napa makes a whole set for that as well as you can find them on ebay. I replaced my cracked 1992 GM V6 with one out of a GM truck and although I had to change everything over (manigolds, wtare pump, oil pan etc.) the motor has worked great and you cant tell the difference! Good luck!

 

[delsol]

Re: difference between boat motor and car motor gm 350

i run on fresh water thier is no reason why i cannot get a gm long block and drop it in and have a good boat for at least 3 yrs. i did it with my buddys boat. we ordered a new gm 350 260 hp 4 bolt main worked out great..will in be perfect.no in budget yes...put some new manis on it all my bolt ons ...i will be up and running fast vrs yanking it out and redoing old one
bob

 

[Don S]

Re: difference between boat motor and car motor gm 350

i run on fresh water thier is no reason why i cannot get a gm long block and drop it in and have a good boat for at least 3 yrs. i did it with my buddys boat.

Then why are you wasting eveyones time asking?

 

[shelikesit]

Re: difference between boat motor and car motor gm 350



hey i just realized i made 2nd class petty officer, i hope ya'll don't take stripes back too - :^

 

[Zackman]

Re: difference between boat motor and car motor gm 350

Don't forget the head gaskets are different too.

 

[delsol]

Re: difference between boat motor and car motor gm 350

i run on fresh water thier is no reason why i cannot get a gm long block and drop it in and have a good boat for at least 3 yrs. i did it with my buddys boat.

Then why are you wasting eveyones time asking?

 

[delsol]

Re: difference between boat motor and car motor gm 350

don. i am a little unsure. this is my first mercurser setup. i said i did put a crate gm car engine in a friends boat and worked out nice..i value your info and am not sure and am seeking advice and help. in the northeast we have all winter to complete this as its cold out. i have no garage or i would do thinks a little different. rebuild what i have...i am not trying to waste anyones time as all replys have beeb helpful
thanks all
bob

 

[roy c]

Re: difference between boat motor and car motor gm 350

cam may have a differant profile, but that is just the tip of the iceburg.
1. anti corosion paint.
2. brass plugs in block where water jackets meet the heads.
3. special water pump with sealed berrings as opposed to automotive type that is lubricated by coolant.
4. brass or ceramic lined waterjacket in intake manifold.
5. brass freeze plugs.
6. as the other posters already indicated, almost all are the heavy duty versions with forged rods, forged pistons, steel cranks, and a cam geared to reach max power in the 3 to 4500 rpm range.
7. longer dipstick tube.

then you have the prehiperals.
1. marine distributer with spark arrestor so boat doesnt go boom.
2. alternator with spark arrestors so boat doesnt go boom.
3. marine carburator with brass sleeves on shaft and anticorosion coating.

you could by a high performance crate motor, replace the cam and freeze plugs, and paint it with anti corrosion paint and get away with it. its what the performance shops do as long as you have the other stuff already. it starts out as the same block, pistons, rods, crank as the heavy duty truck motors.

marine app doesnt mean forged internals

 

[Bt Doctur]

I think after 15 years he got it figured out.
post your own problem not someone else`s