Tuning up a 93 mecr 3.0

[Tail_Gunner]

Looking at this old engine brings me back to the days of points and plugs what nostagla. With that said this is a boat motor so some of the old methods i have used may not apply here and i am looking for some advice.<br /><br /> In setting the dwell that is a no brainer, now however when i was tuning cars ignition timing i would loosen the distribor and advance or retard the timing with the engine under a full load (Power braked) it was easy to find the sweet spot as the car would pull hardest at a certin advance and the rev's would peak. very seldom the results be in factory spec but it would lead to great results after a litte carb tweaking. Has anyone tried such a method or better said cant this be done to a boat motor. <br /><br /> Last question is simple, do these little carbs have a low and high speed jets? I have ordered a manual guess im just a bit curious here. It's been almost 30 years since i have done this.

 

[Chris1956]

Re: Tuning up a 93 mecr 3.0

Tail, The manual will set you straight. You likely do not have points. You should just check the timing with a light, according to the manual. My Mercruiser has all the advance mechanisms built into the ignition module. No vacuum or centrifical advance needed. You must, however, idle the motor at the correct RPM to set or check the timing, or the auto advance will muck things up.<br /><br />Change the plugs, cap, rotor and maybe plug wires, and you are done.<br /><br />Carbs are very much like the auto version, before switch to FI in cars. You likely have a 1 bbl Rochester Marine carb. Same as auto except no overflow into the bilge, and some marine-rated gaskets.

 

[Don S]

Re: Tuning up a 93 mecr 3.0

Below is a link to the Mercruiser service manual for your engine.<br /> http://www.boatfix.com/merc/Servmanl/13/13covr2.pdf <br />and here is one for your outdrive,<br /> http://www.boatfix.com/merc/Servmanl/14/14cover.pdf <br />Just move your cursor over the pages to locate the links and the index.<br />You probably have the EST (Electronic) distributor which was about the most common in 93. There is a special procedure for setting the timing.<br />You also have a 2bbl carb, a Rochester look alike known as a Mercarb. Don't try to get a Rochester kit for it, won't work.

 

[Tail_Gunner]

Re: Tuning up a 93 mecr 3.0

I was almost excited,hands on finally after 30 years.EST is really a better way to go (stability) thankyou very much for the input and those links worked great. Just wish i had posted this a few days ago could have saved a bit of dough and those on line manuals are quite comprehensive

 

[Rock Hall]

Re: Tuning up a 93 mecr 3.0

Don,<br /><br />Do you subscribe to a service to get the on-line manuals or are they free?<br /><br />Mark

 

[Don S]

Re: Tuning up a 93 mecr 3.0

boatfix.com has them online for free, but there are only a few manuals, mostly just the drives. Only 1 for the 4 cylinder, a V6 and one bigblock if I recall correctly.<br /><br />Have a look, there are also some tech manuals for the engines for a few years.<br /><br /> http://www.boatfix.com/merc/mainmenu.pdf

 

[Rock Hall]

Re: Tuning up a 93 mecr 3.0

Thanks Don,<br /><br />Only a few models, but for someone like me that just wants to learn more about marine mechanics, there's lots of good reading there.<br /><br />Thanks Again for the link.<br /><br />Mark