1978 bayliner 240hp chrysler I/O volvo outdrive

Joined
Oct 25, 2004
Messages
11
Hey everyone,<br />I am Jon.A 24 y/o first time boat owner.My grandpa designed and built farallon ocean fishing boats.He started the company and sold it before he died.But needless to say I have been around boats and fishing since I could walk.Anyways back to my recent problems <br /> .I just purchased a 1978 Bayliner ,20 feet,w/240 hp chrysler engine I/O (after market)and a Volvo penta outdrive(original).I took it out for a trial run the other day and ran into a few problems.It starts fine until you get out far enough lol.found out the carberator wasn't doing its job.I had to take the flame arestor off and hold the valve/choke closed to get any gas then crack a lil to give some air while my friend drove us back to dock.once you get going it runs fine.So I will need a new/rebuilt carberator.The next thing I noticed was temperature ,at a constant speed/RPM why would the temp cycle from 180 to 160 and back.It goes to 180 deg. then drops to 160 deg. within 30 to 40 seconds.Last but probably most important.AS I said before I have a 20ft bayliner 1978 w/240 hp chrysler and volvo penta outdrive.At 4000 rpm with the engine working its hardest, reved to the max, the boat will only go 18-20 mph top speed .Seems like its working way to hard for how fast it moves.My friend says it might be the diameter and/or pitch of the prop.It does have the original outdrive and a diferent engine.If anyone knows about what I am going through, or can help in any way.That would be cool <br />later Jon
 

JB

Honorary Moderator Emeritus
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Mar 25, 2001
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45,907
Re: 1978 bayliner 240hp chrysler I/O volvo outdrive

Moving to I/O and Inboard Engines
 

tommays

Admiral
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Jul 4, 2004
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6,768
Re: 1978 bayliner 240hp chrysler I/O volvo outdrive

need to no if FWC or sea water <br /><br />fwc 160 to 180<br />raw 140 to 160<br /><br />temp junping around bad connection ???<br /><br />speed is the boat in the water or kept on trailer <br /><br />is bottom clean<br /><br />many older boats suck up and keep a lot of water weight<br /><br />tommays
 
Joined
Oct 25, 2004
Messages
11
Re: 1978 bayliner 240hp chrysler I/O volvo outdrive

Hey tommays,<br />I am using it in fresh and brackish water,Delta and bay.It is stored on a trailer and has only seen the water once since I bought it.Before I bought it , it sat in someones driveway.I have found out most of the problems.I think I have narrowed the speed problem to wrong prop size.It has a diferent engine and the same prop it came with. The prop size on it 14 diameter and 17 pitch.I was looking at a prop buyers guide (http://www.a1discountprop.com/volvo-michigan.htm) It says for 190-255 hp the prop should be more like 15 diameter and 19 pitch for a 18 to 20 foot boat.I think the engine it came with was more like 150 hp.Maybe thats why such the small prop.I dont know about the temp though someone suggested it could have a car thermostat installed. They said to get 140 degree boat therm.<br />Later <br />Jon
 

Dunaruna

Admiral
Joined
May 2, 2003
Messages
6,027
Re: 1978 bayliner 240hp chrysler I/O volvo outdrive

Jon, welcome to i-boats.<br /><br />Determine what the max RPM is for your engine and use that as a reference for propping. Without knowing your engine details I would have thought that 4000RPM is a bit low. Changing from 17" to 19" will lower your WOT RPM, I believe you need to go the other way, maybe 15" - that'll put your RPM around 4400. My guess is a 15" x 15" will do the trick.<br /><br />Take a peek at this: http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000030 <br /><br />Having a clean bottom is also a major factor, good for the boat too :D <br /><br />Aldo
 
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