Mercruiser 140 timing

I have a 1986 Blue Water with a Mercruiser 140. I know nothing about boats but am fairly fluent in car engines, I was sure the timing was out based on the sound and locking sounds when turning it over and when getting on it there was a lot of spitting and sputtering before it would finally get going.

I threw a timing light in the number 1 plug (plug closest to the crank pulley) and the mark was way off the gauge at idle (gauge goes to 12 BTDC and I would guess it was around 30). The plaque on the engine says the timing is 6 BTDC so that is where I set it to. I am being told I set it wrong. I have been unable to locate a manual for my engine so could someone please aid me in how to set this timing?

As I said it is a 1986 model 140 Mercruiser, it has points so is not electronic ignition, and there is no vacuum line on the distributor on this one so I am assuming no vacuum advance.

Thank you for any help you can provide.

Re: Mercruiser 140 timing

That would be the proper setting but at 30 degrees, one might think the advance weights in the distributor are stuck.

Re: Mercruiser 140 timing

Silvertip said:

That would be the proper setting but at 30 degrees, one might think the advance weights in the distributor are stuck.

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I know that 6 BTDC is the proper setting but did I check it correctly? After setting it back to 6 degrees I did throttle it up and it seemed to be advancing okay.

Re: Mercruiser 140 timing

You have to set the timing at 6? while the engine is at idle rpm (650-700). If you have the engine running faster, it will start advancing and you won't have the proper timing.