Mercruiser 3.0 lx sea trial and compression specs.

[achris]

... I think my tach may be off as well....

Yeah, you need to use a calibrated tacho, like one in an advanced timing light...

 

[Guymontag]

I've read that a bad tach will stop the ignition from firing? The boat runs for 20 then it'll cut off. I'll wait ten mins then it'll start then run for 20 cut off. Etc. When I was trying to start I pulled the middle wire iff the dustrubitor and tried to jump it to the motor. No spark. 10 mins later it'll run. I did notice my tach was jumpy at higher rpm but it settles down. Any how I got a new ignition to put in this weejend. Looks really simple. I also have an ignition module to put in to. But I can't find any good tutorials on that looks like a little more involved..i rprplaced the check valve diptube and ran a new fuel line. Just in case it was a fuel issue. Any thiughts?

 

[alldodge]

A bad tach can kill the spark. Removing the gray tach wire off the coil will allow spark to return if this was the issue.

Module is easy to replace and most come with an instruction sheet

 

[Guymontag]

I can just disconnect the tach via gray wire, While I trouble shhoot? The boat will run this way thus eliminateing one variable?

 

[alldodge]

I can just disconnect the tach via gray wire, While I trouble shhoot? The boat will run this way thus eliminateing one variable?

Correct

 

[Guymontag]

Thanks I'll post my prop results Monday! P.s. Been looking at the electronic ignition conversion. I've got the Delco esp distributor. I assume it's from 93. Guess it'll be good peace of mind to replace this while I'm tbere? Not much left to replace after that.

 

[fishrdan]

I've got the Delco esp distributor.

Delco EST distributor in the engine already??? If so, it's an electronic, no conversion needed, and it's MUCH better than the electronic conversion kits.

 

[Guymontag]

Not sure I found some pictures of Delco Voyager distributor mine looks the same I haven't pulled the car off yet. I will tomorrow when I change out the module. I'll know for sure then. If not is it safe to say the electronic is better worth the money?

 

[fishrdan]

Points are easier to troubleshoot, but need maintenance every year or two. Electronic ignition is worry free, until there's a problem, then it's much more difficult to troubleshoot and repair...

I used to run points dizzy in my engine, but the shaft bushings were shot... Been running an EST for 8+ years without touching it. Change plugs every couple of years and check that the timing is right.

 

[achris]

... Change plugs every couple of years and check that the timing is right.

Ever found the timing to have drifted?

 

[fishrdan]

Ever found the timing to have drifted?

Nope, timing has been spot-on every time. Old habits are hard to break.

 

[Guymontag]

So I changed out the ignition coil and ignition module. Boat runs nice and smooth now and doesn't cut off every 20 mins like it did. I think it may already have the electronic distributor but I'm not sure heres A pic. And the 23 pitch prop got me to 40mph at 4500-5000 rpm ( I know way to much) problem is it'll stall out if the hole unless I really baby it.( It was also really choppy and windy). I threw the 21 pitch on it'll bog down but won't stall out of the hole but gets up to 30-33 at 5000rpm. Haha so I guess I gotta keep the 21 unless I could figure a way to get more low end torque? To get the 23 to get me out of the hole?

 

[Guymontag]

Can't upload my pics size excedes 2.0...

 

[Guymontag]

Trim tabs? Whale tail? 4barrel headers through exhaust and a shot of nos haha jk.

 

[achris]

NEVER put one of those fins on the drive. Very bad idea.

Having to 'baby'it on acceleration is a sure sign the carb needs pulling off and cleaning and resetting...

 

[alldodge]

Agree, carb problem, and if your tach is accurate at 5000 rpm, then you need to put the 23 back on. Your max rpm should be 4800. Check with a accurate tach

 

[achris]

...Check with an accurate tach

And the dash tacho is not an accurate tacho.... Use a shop calibrated tacho, or the digital tacho in a timing light...

Chris.....

 

[Guymontag]

Carb rebuild? Or just unbolt and soak in seafoam or something? Also I've heard SS is faster then alu. But I've been told with my house down at 135 I won't see a diff.apparently one of them cupped props would help? If so any idea how much?

 

[Guymontag]

One more thing... from reading the past forums sends a tach tool is easy to hook up positive wire to the gray wire on the ignition module. I didn't understand what or where the ground from the tach goes. just to the block? Is there a digital in dash tach you guys recomend thAt would be just as good as a timing tool tach? Might aswell get one and verify. Motor purrs like a kitten and revs up well in nutrel. Even the 21 pitch it bogs out slightly but doesn't stall. The 23 makes her stall out pretty easily. God kknows how old the gas is thats in there. I had 12 gallons of old gas and topped it off with 93 and a can of seafoam. Maybe the shitty gas? I'm trying to run all the old stuff out and put ethanol free 90in it for winter lay up but damn thing is sipping gas. Haha what a good thing to complain about.

 

[achris]

A soak in seafoam, or any other snake oil is not a rebuild and clean out... You need to remove the carb from the engine, strip it down to its component parts and soak them, preferably overnight, in PROPER carburettor cleaner. Then blow the whole lot dry, including the tiny passages inside the carb, and reassemble it, and set all the various adjustments, according to the manual...

The variation between SS and aluminium propellers is only really felt at higher horsepowers, up around 250 and above. The main reason to run stainless is it's durability... As for 'cupping', all modern propellers (that you are likely to use) are cupped... You won't see any difference with a 3 litre engine...

Clean out the carb, or get it done, get an accurate tacho on the engine and start your trials again... This '4500 to 5000' isn't anyway near close enough for setting up the boat.... You need to be able to report engine speeds accurately and within about 50-80 revs.... Use a shop or digital tacho and a GPS for speed. (Download some truly excellent GPS apps onto your phone and spend nothing. ;-)

Chris.......