Cobalt Needs a Ring and Valve Job

[bulachip]

Hello...

it has been a while and I now have a new boat...

I am the proud owner of a 1988 Cobalt 203 with a 5.7L 260hp 4bcb and an alpha one outdrive.

Basically the boat seemed under powered this summer and you could feel that the engine was missing every so often.. so at the end of the season i checked the compression and two of the cylinders are below 100....

I do not have really deep pockets but am always looking for an upgrade, so before I give my mechanic the OK to rebuild this , should I look at adding any performance goodies???

I was thinking about adding vortech heads... and maybe a cam.... any suggestions??


Also- if the boat ran 48-49 with the 2 dead cylinders, how fast do yall guess she may run with a rebuilt stock engine? I am really only looking to get up to the 55-60mph range.



Thanks for the help!

Harry

 

[Bob_VT]

Re: Cobalt Needs a Ring and Valve Job

I would not get glorified and change anything. A fresh running 5.7 and a decent prop should put you at 55 mph. I would rebuild for reliability ans stay stock. Consider this...... your boat is a 1988 and just as an example.....let's say it's book value is 4K and you put 2K in motor upgrades...... you will still have a boat worth 4K. That is the nature of the beast. I would buy a stock boat/motor over one that has been "tweaked" any day

 

[tpenfield]

Re: Cobalt Needs a Ring and Valve Job

Yea, you might want to check the price of a new long block versus a rebuild.

Unlike automotive applications, there is a limited amount that you can do with cam shafts for a boat, since they need to have a fairly low amount of valve overlap. So, not as many possibilities to 'soup up'.

 

[JASinIL2006]

Re: Cobalt Needs a Ring and Valve Job

For comparison purposes, my 19' Larson has a 350 Mag, 4 bbl. carb, Alpha One and with my three-blade prop I can hit 60 mph. I agree with Bob_VT: I bet you could get 55-60 with a good 5.7 stock motor and the right prop.

 

[Bondo]

Re: Cobalt Needs a Ring and Valve Job

Hello...

it has been a while and I now have a new boat...

I am the proud owner of a 1988 Cobalt 203 with a 5.7L 260hp 4bcb and an alpha one outdrive.

Basically the boat seemed under powered this summer and you could feel that the engine was missing every so often.. so at the end of the season i checked the compression and two of the cylinders are below 100....

I do not have really deep pockets but am always looking for an upgrade, so before I give my mechanic the OK to rebuild this , should I look at adding any performance goodies???

I was thinking about adding vortech heads... and maybe a cam.... any suggestions??


Also- if the boat ran 48-49 with the 2 dead cylinders, how fast do yall guess she may run with a rebuilt stock engine? I am really only looking to get up to the 55-60mph range.



Thanks for the help!

Harry

Ayuh,.... How much is yer Mechanic wantin' to rebuild yer motor, Not includin' pullin', 'n reinstallin' the motor in the hull,..??
Just the Rebuild of the Long Block,..??

Take that number, 'n search up rebuilt replacement long blocks for yer 5.7l boat motor,...
The crate motor may well be Cheaper,...

Yer Mechanic will still need to swap the long blocks, unless yer turnin' yer own wrenches,...

Vortec heads will give ya an honest 20 hp kick,.... Might get ya the low/ mid-50s,...

 

[Walt T]

Re: Cobalt Needs a Ring and Valve Job

DO NOT let your marine mechanic rebuild it. Get a reman from a machine shop with a warranty. Better yet find a stroker motor long block for that. You'll love it. The past 40 years I have seen so many badly built engines by so called mechanics who didn't bother with machining or even checking cylinders and looked like they were put together in a dust storm. Just Honing cylinders and installing new rings and bearings is NOT a rebuild in my book. You want an engine that is built to specifications, bearing clearances verified, cylinders bored out, cam bearings replaced and crank align bored. Then you'll get an engine that will last. As Mr. Bondo points out, check out all your options. A 383 stroker is an option if you're looking for more performance. If you can develop a relationship with a machine shop, especially one that understands marine performance, you'll find many many options.
Many a time I have been asked to check out a motor that was "Just rebuilt" by a marine repair shop by the customer who is at wits end trying to get them to warranty it. A small marine repair shop may not be able to afford to buy you another engine when the one they built throws a rod through the block whereas a good established builder can do it instantly. Now I don't know your mechanic for all I know he's Don Garlits reincarnated, I'm just saying listen to the guys here and carefully research this, educate yourself, and only then will you be able to make a sound decision. Rebuilt and remanufactured engines have an above average rate of failures in the automotive repair industry. I think it's mostly because the builders can't control the parts swap over and the installation.
Good Luck