omc 5.7 motor locked up, have questions

[fivebites]

I have a 1986 22ft open bow ski boat, the motor locked up on me the other day. My question, can i simply get a chevy 350 and put the exhaust manifolds, carb, ect. on a stock chevy car engine, or is there something special about the marine engine. Also I have planed on installing thru hull exhaust, has any one changed this over from regular exhaust? is there any web sites that I can look at for this? any help or suggestions would be helpful. Thanks

 

[Ralph 123]

Re: omc 5.7 motor locked up, have questions

Hi,<br /><br />There are lots of differences - 4 bolt main, cam, pistons forged not cast, etc. Go to amazon.com and read the free excerpt of small-block chevy marine performance to read about them. You should buy the book if you want to do any sort of performance mods. Awesome book<br /><br />The good news (if there is any) is that you can get a SBC marine 350 for about $1,200 and you swap tin, alt, carb, etc.<br /><br />If you are going to switch to thru-hull first understand that you will not see any real HP increase. The reasons are also explained in that book. You may also need to put in a silencer/muffler depending on your State's regulation. If you want more HP you would need to do marine headers. Second, you'll need a blocker plate for your gimbal to block up the existing axhaust ports.

 

[akriverrat]

Re: omc 5.7 motor locked up, have questions

i tried really hard to keep right on going, but...four bolt mains, forged cranks, forged pistons are the exception in marine engines. most are hardly distinguishable from a gm or ford light truck motor. especially the cam. big difference in freeze plug material, stainless steel head gasket, and saltwater resistant materials in waterpump. if you use a closed cooling system even those are optional.

 

[Fouled Plug]

Re: omc 5.7 motor locked up, have questions

I'd have to agree with riverrat. Some hi-po, high end I/O's have forged bits and 4 bolt mains, but the average unit isn't radically different from a car/truck engine. Lots of GM crate and NAPA reman powered boats around here!