rebuilding a 153 ci chevy for boat service

[fred0709]

Sirs<br /> I am rebuilding a 153 ci chevy mtr I salavaged from a 1970 nova to replace the tired 120 hp merc in my 1969 185 SRV Sea Ray. the local machine shop said the engines were the same with the exception of; the merch has forged pistons, different cam, heavier valve springs, better gaskets. I will be retaining the merch altenator, starter, distributer, intake/exhaust, carb, for safty reasons. I would like to buy my rebuild parts from a hi-performance auto parts supplier for economics and also they have a better selection of cams. The cams they supply have a higher lift than stock. The duration and lobe seperation I cannot compare as I have not been able to find those specs for the stock cam. They claim they make excellant marine cams.<br /> My questions; what are the stock merch cam specs, as this boat only sees fresh water do I have to use marine gaskets, water pump?<br /> I am sure many others have done this before me. Am advice would be greatly appreciated!! thanx!!;fred

 

[DJ]

Re: rebuilding a 153 ci chevy for boat service

fre0709,<br /><br />I would definetely use the marine gaskets and water pump. Even though you boat in fresh water, there is still alot of galvanic action going on. This is particualrly important for the water pump.<br /><br />Cams: try to stay with a cam that produces a very flat torque curve. In other words, if you see a graph of the torque curve, look for a quick rise to "peak" torque and a long flat "table" on the torque line.

 

[SS MAYFLOAT]

Re: rebuilding a 153 ci chevy for boat service

Hi Fred,<br /><br />I rebuilt my 1966/120hp several years ago. Found out that my cam was not a marine cam. Got one through my local Mecrusier dealer, it was around $110. Made a big difference on the response of the engine. For your gaskets, check with your local NAPA Store, they have a listing for marine parts at a resonable price. Check to make sure that the crankshaft is a steel crank. Everything else that your doing sounds great. Good luck

 

[coupedeville]

Re: rebuilding a 153 ci chevy for boat service

Have a look here:<br /> http://www.cliffordperformance.com/home.htm

 

[fred0709]

Re: rebuilding a 153 ci chevy for boat service

thanx for responses guys. the machine shop was wrong. the car mtr I am rebuilding has what looks to be a cast crank. I am going to look for a used one. If they are too expensive I will pull the one out of my boat next spring. again thanx, fred

 

[Capt Ken]

Re: rebuilding a 153 ci chevy for boat service

Dang, there was still a four banger hanging around in a junk Nova after all these years. Musta been hidden real good. Just curious, what did it sell for in the junk yard?

 

[coupedeville]

Re: rebuilding a 153 ci chevy for boat service

I wouldn't fret too much over the cast crank. Lots and lots of boats [not to metion cars & trucks] running around with cast cranks.<br />Usually the connecting rods will give up before the crank does.<br /> Don't flog the poor thing too hard for too long, and you'll never know the difference. Make sure it's straight, and doesn't have any cracks.

 

[fred0709]

Re: rebuilding a 153 ci chevy for boat service

I paid the local junk yard $200 for the whole car capt ken. I kept the mtr and gave the rest to a couple of friends who are into cars. It was heading for the crusher soon so I'm glad we could rescue it. It had 1997 plates on it. <br /> A cast crank in a boat. I didn't know I could do that. thanx coupdeville I will consider that.

 

[Capt Ken]

Re: rebuilding a 153 ci chevy for boat service

Thats a testament to those old four bangers. Timex has nothing on them. Help save our heritage, put an old car on blocks in your backyard.

 

[coupedeville]

Re: rebuilding a 153 ci chevy for boat service

If you're still concerned about that cast crank, this may help: GM has a brand new 8.1 litre engine for the marine market, the Vortec HP3 8100.<br />Before they pick an engine to marinize, they take it and run it on a dyno for 300 hours at wide open throttle to see if the design will take the strain. It did, and yes, it has a cast iron crank.

 

[ODDD1]

Re: rebuilding a 153 ci chevy for boat service

Fred, I wasn't aware merc ever used a forged crank in their 4 cylinder motors...every one I have ever had apart had a cast crank....

 

[geriksen]

Re: rebuilding a 153 ci chevy for boat service

Cast crank is fine. Marine head gaskets, brass freeze plugs, good valve springs and the cam is all you need. Buy the factory cam if you can.<br />Get it as close to stock marine specs as you can. Ignore the Hi perf B.S., you need tourque and with that engine you can't afford to give any away.