350 GM Crate Engine ?

[rockdog57]

I'm thinking of changing out the gutless 305 in my crestliner next summer. I've looked at crate motors and have a question about the GM 290 Horse HO 1299529. I know it says not for marine use in the description. I guess my question is why? If it was just brass plugs or the cam had to much lift and duration?
I've thought about picking up a used 350 and having the local machine shop rebuild it. But that might be a crap shoot on what I'm buying.
I don't really need a 290 horse engine. I'd be happy with something 260 or better. Any suggestions? I don't want to spend over $2500.00

 

[Silly Seville]

Re: 350 GM Crate Engine ?

1. They will not warranty it if they discover (and they will) that you installed it in a boat.
2. You can have a used 350 with roller valvetrain and Vortec heads built at a shop for less than $2500
3. If you're going to spend the money, get as much power behind you as possible. A Merc 260 is NOT putting 260 hp into the water! Have a 300 hp engine built, and you will have 260 hp at the prop.

 

[26aftcab454]

Re: 350 GM Crate Engine ?

check the restoration section for Frisco Boater rebuild of this Glastron. ( sorry I cannot post link)
it is on towards the last quarter of the build.
it is a 350 crate motor with a RV cam and a few mild mods---$1200.
it is a bat outta hell.

 

[Howard Sterndrive]

Re: 350 GM Crate Engine ?

I don't really need a 290 horse engine. I'd be happy with something 260

That 290 crate is a 260HP motor when you put it in a boat and prop for WOT of 4600.
It only makes 290 when you rev it over 5,000

Those 290 crates are virtually identical to the Mercruiser and OMC 260/350 of the late 70's early 80's

The warranty is probably marketing - they don't want to get involved with marine customers.
A few people on this board have used the crate 290 5.7

I used a crate GM V6 in my boat. works great.

 

[Bondo]

Re: 350 GM Crate Engine ?

That 290 crate is a 260HP motor when you put it in a boat and prop for WOT of 4600.
It only makes 290 when you rev it over 5,000

Those 290 crates are virtually identical to the Mercruiser and OMC 260/350 of the late 70's early 80's

The warranty is probably marketing - they don't want to get involved with marine customers.
A few people on this board have used the crate 290 5.7

I used a crate GM V6 in my boat. works great.

Ayuh,.... I completely agree with Howard,.....

 

[billbayliner]

Re: 350 GM Crate Engine ?

Agree with Howard.. watch closely the rpm where HP is rated. For example.... the Vortec 315-320 is rated at near 5,200 rpm. We don't run at this rpm.
If you custom build one you can use a 'squish' style piston and get a way from the full dish piston that the crate motor will have in it. These can be a D dish, Revese Dome, or any combination that suits the cylinder head chamber volume.
Read Dennis Moore's Small Block Chevy Marine Performance and his section on quench or squish, or articles by Jeff Smith and it may convince you to do this. Cost should be well under $2,500.

 

[halfmoa]

Re: 350 GM Crate Engine ?

+1 on all of the above and I'll add that I've never met anyone nor came across anything in my life that had too much horsepower!

 

[rockdog57]

Re: 350 GM Crate Engine ?

Huh??? If the current V-8 isn't enough then yes you do need more HP. I'd suggest a remanufactured long block from rapidomarine. Won't cost anything near your $2,500 limit.

The 305 in my boat is a 200 horse motor. Yes I know I need more horse power. Thanks for all of your responses! I didn't realize that the 290 would only get me 260 at the prop. I have read that the alpha 1 out drive is only rated for 300 horses,so I was concerned with busting things if I exceeded that.
I've been watching the local ads for a rebuilder motor. But I am just not sure what motor to look for. There are 10,000 different versions of the 350 out there. I might end up with a low horse smogger out of who knows what.
My 305 has a two barrel carb so I'll have to buy a new intake and carb in the $2500.00 budget.
Any more knowledge you guys have, I sure would appreciate!http://forums.iboats.com/images/icons/icon7.png

 

[mxcobra]

Re: 350 GM Crate Engine ?

check theese out.... http://www.usengine.us/mercruiser.html

 

[Howard Sterndrive]

Re: 350 GM Crate Engine ?

If you custom build one you can use a 'squish' style piston and get a way from the full dish piston that the crate motor will have in it.

no need, Bill..the 290 crate already has these pistons - perfect for marine - and the heads are 76cc... all identical to a 1970's Mercruiser or OMC...right down to the 2 pc rear main seal.

 

[Silly Seville]

Re: 350 GM Crate Engine ?

I didn't realize that the 290 would only get me 260 at the prop. I have read that the alpha 1 out drive is only rated for 300 horses,so I was concerned with busting things if I exceeded that.

The things you must understand are 1. Engine manufacturers used to advertise with crankshaft/flywheel horsepower. That changed in the late 80's (if memory serves me correct) and they started using wheel horsepower (cars) or prop HP. The difference is essentially the parasitic (frictional) losses that are incurred whenever there is an intermediate device connected between the engine and it's final component of propulsion. I.E. the transmission in a car, or in our case, the outdrive. This "loss" of power is understood to be @ 30hp in an Alpha drive.

2. The Alpha may be RATED for 300hp, but it is understood that they can withstand 350hp or even more; IF one does not abuse the privilege! In other words, you can have a high HP engine in front of your drive, and the drive may last its serviceable life without failure, if you treat it kindly with your throttle hand. Abuse it enough with that much torque/HP on tap, and you will grenade the gears. There is a reason that Merc only put a 454 in front of the Alpha for 3 years...then they developed the Bravo series. There is much written about this. I still see 250 and 268 Sundancers running around on our lake with 454/Alphas, and they are 25 years old. Respect for the machinery has a huge impact on its longevity.

 

[Howard Sterndrive]

Re: 350 GM Crate Engine ?

I didn't realize that the 290 would only get me 260 at the prop.

290 crate gives 260 at the flywheel at marine rpm
probably more like 230 at the prop

 

[rockdog57]

Re: 350 GM Crate Engine ?

290 crate gives 260 at the flywheel at marine rpm
probably more like 230 at the prop

Thanks you guys for furthering my 350 education! So if 290 gets me 260 at the prop and due to hp at 4500 on the 290 gets me 230 at the prop. Then that raises another question in my simple mind.:facepalm: My 305 is advertised as 200 horses. Are they supposedly saying that's 200 at the prop?
If that's the case, then 230 at the prop just doesn't sound like that much more. Or am I totally over thinking this.

 

[RogersJetboat454]

Re: 350 GM Crate Engine ?

The things you must understand are 1. Engine manufacturers used to advertise with crankshaft/flywheel horsepower. That changed in the late 80's (if memory serves me correct) and they started using wheel horsepower (cars) or prop HP.

You're right for boats, wrong for cars. Unless otherwise stated, a HP figure given for any vehicle is still flywheel HP. The big change that happened for cars occurred in the early 70's when manufacturers switched from rating engines with their gross HP (no accessories) to rating engines with their net HP (all accessories/exhaust installed as if the engine was installed in the vehicle).

 

[Howard Sterndrive]

Re: 350 GM Crate Engine ?

My 305 is advertised as 200 horses. Are they supposedly saying that's 200 at the prop?

depends on the year.... some 305 4 BBL made 230HP at the flywheel, which would be around 200 or 210 at the prop
305- 2 BBL carb probably around 200HP at the flywheel.... some 305's had smaller heads that derated them below 200

I know OMC had a 305 2BBL in 1980 that was sold as a "200" and that was flywheel HP
I think after 1985 or 1986 most manufacturers started rating at the prop, and some also started just naming motors by displacement or other model designations.

all other things being equal, a GM290 crate with a 4 barrel, is a 60HP gain over a 305 2 BBL, and a 30HP gain over a 305 4 barrel (305 with the larger heads)

 

[91rr]

Re: 350 GM Crate Engine ?

I'm thinking of changing out the gutless 305 in my crestliner next summer. I've looked at crate motors and have a question about the GM 290 Horse HO 1299529.

I just installed this exact engine in my boat to replace a clapped out 305. I did change out the freeze plugs but that was it. For $1200 being a brand new engine not a rebuilt one you can't beat it. The only thing that I will do this off season is change out the cam to a marine cam. It comes with an automotive cam that just doesn't put out that low end torque that a boat needs. As far as the warranty goes it just all depends on where you buy it.

 

[joewithaboat]

Re: 350 GM Crate Engine ?

I just installed this exact engine in my boat to replace a clapped out 305. I did change out the freeze plugs but that was it. For $1200 being a brand new engine not a rebuilt one you can't beat it. The only thing that I will do this off season is change out the cam to a marine cam. It comes with an automotive cam that just doesn't put out that low end torque that a boat needs. As far as the warranty goes it just all depends on where you buy it.

That's a really good price on that engine! Where did you find it ?