1978 MFG Caprice with OMC 140 Timing issue?

[navillus11]

Hey everyone I am new to boating and this website, I purchased a 1978 MFG Caprice with an OMC 140 engine in it. I had it looked over at the marina near my house and he told me it needed a new timing chain and gear set he said it was stretched from age and that it was jumping timing, He also stated it was running on 2 cylinders (inline 4). He performed a compression test and all 4 cylinders read compression of 130 PSI. I was talking to a mechanic friend of mine and he said if the timing chain was truly jumping timing that the compression on 2 of the cylinders would be less due to the timing being off. I have not had enough experience with boats to know who to believe, I don't mind spending the money ($400ish) but I want to know for sure that's the problem. When I was performing the winterization 2 weeks ago I heard a slight noise that could have been the chain hitting the cover... It idles pretty smooth, When I would first start it the engine would idle rough I would increase throttle to about 1000 and it would smooth out, then bring throttle back to 600 it would idle fine. Any advice would be greatly appreciated!!!


Thanks for your time!

 

[Howard Sterndrive]

Re: 1978 MFG Caprice with OMC 140 Timing issue?

dunno what school your "mechanic" went to, but your engine doesn't have a timing chain. The cam is driven by fiber gears.
an engine wouldn't idle at all if the chain slipped more than 1 tooth once.... it would never restart
you can get a manual and start reading about diagnostic steps, or take it to another shop... that guy is not going to help you.
might just need a tune up... gumming up and rusting of advance weights and springs in your distributor a common old age disease of i/o motors with points ignition

 

[navillus11]

Re: 1978 MFG Caprice with OMC 140 Timing issue?

So does that mean that he was completely off about it needing a timing chain because there isnt one? Or maybe he was referring to a gear being stripped out would that be possible?

 

[Howard Sterndrive]

Re: 1978 MFG Caprice with OMC 140 Timing issue?

not possible... he's out to lunch- I modified my previous post

 

[navillus11]

Re: 1978 MFG Caprice with OMC 140 Timing issue?

I have the original FSM for my boat, Maybe its a combination of poor gas, mechanical advance on the distributor being off. I replaced the points and the condenser and the plugs and distributor cap, maybe I need to check the mechanical advance is there any trick to that? Something along the lines of hand turning the rotor correct?

 

[navillus11]

Re: 1978 MFG Caprice with OMC 140 Timing issue?

Is it possible for those fiber gears to be worn out? if they are the boat wouldnt start right?

 

[Howard Sterndrive]

Re: 1978 MFG Caprice with OMC 140 Timing issue?

remove the points mount plate and visually inspect the weights and springs under it.