2.5L Merc Rochester Carb too high WOT?

[pigrge]

Can this really be happening? I bought a shop tach from Advance Auto and it tells me that I am spinning at 5600 RPM!!!! Can this be true? My regualr tach on the boat is telling me I am maxed out at 3800!!! Argh which do I trust!?!? I like this boat but it is really getting to me. The boat and motor are a 1982 with a Pre Alpha Outdrive on it. I am the one who just had all of this questions about the timing. Speaking of that issue as well, the timing is another brain buster. If I set the timing where it should be at 8 degrees BTDC I get a bad mis under load coming out of the wake zone and then at the top end it misses intermittenly and getting out of the hole makes the boat sound AWFUL!!! But if I advance the timing quite a bit and start from there it goes nice and strong but I get a wierd ticking noise coming from somewhere back there. Argh! Any help? Maybe these two issues are related. Thanks!
Ryan

 

[pigrge]

Re: 2.5L Merc Rochester Carb too high WOT?

Also my coil says it must be used with an external resistor what is this?

 

[pigrge]

Re: 2.5L Merc Rochester Carb too high WOT?

Man I am filling up my own post, ohh well, I just looked up the ignition coil that is supposed to be on my engine, and it says that the number is supposed to be 32193 and I have 2476C. Could this be a problem?

 

[MikDee]

Re: 2.5L Merc Rochester Carb too high WOT?

Can this really be happening? I bought a shop tach from Advance Auto and it tells me that I am spinning at 5600 RPM!!!! Can this be true? My regualr tach on the boat is telling me I am maxed out at 3800!!! Argh which do I trust!?!? I like this boat but it is really getting to me. The boat and motor are a 1982 with a Pre Alpha Outdrive on it. I am the one who just had all of this questions about the timing. Speaking of that issue as well, the timing is another brain buster. If I set the timing where it should be at 8 degrees BTDC I get a bad mis under load coming out of the wake zone and then at the top end it misses intermittenly and getting out of the hole makes the boat sound AWFUL!!! But if I advance the timing quite a bit and start from there it goes nice and strong but I get a wierd ticking noise coming from somewhere back there. Argh! Any help? Maybe these two issues are related. Thanks!
Ryan

Chances are the shop tach is not set right for the 4cyl marine engine, and the external resistor should be one of the small wires (resistor wire) going into the "ignition side" of the coil, not the "distributor side", as original equipment, I'm not sure of the color?,,, Timing, are you sure you have the timing light on the spark plug wire for cyl. #1?

 

[pigrge]

Re: 2.5L Merc Rochester Carb too high WOT?

The timing light is on the numero uno cylindero my friend, I am not drinking tonight!!!! I do have the tach set for a 4 cyl. engine. Not too sure about the marine part, but it is set to the 4 cyl correctly. As for the resistor ummmmmm, not too sure either.... The "book" tells me that that is supposed to be purple. Thats good. Hopefully...but what about the numbers on the coil? Should I just assume this one is junk witht he 2476C number on it, and bite the forty dollar bullet and get me the right stuff in there for sure? Any way of checking these things to see if they are doin what the are supposed to be doin?

 

[wallydc2]

Re: 2.5L Merc Rochester Carb too high WOT?

I have the same problem, my shop tach reads 5600 and my guage reads 3200. I dont know which one is correct either. I THINK that the shop tach is telling you exactly what the engine is putting out and the guage is telling you what the engine is actually doing. This would be a good question for the pro's. Hopefully the read this soon.

 

[whywhyzed]

Re: 2.5L Merc Rochester Carb too high WOT?

A third tach will create a democracy..... I suggest a phototach that reads a reflective tape you stick on the crank dampener- eliminates any point problems, or spark/dstributor issues from offering up weird tach readings.

The dash tach is counting the number of sparks out of the coil.
The tool tach is counting number of sparks to the #1 cylinder.

A coil/points/condenser issue can make those 2 read weird.

 

[searay3]

Re: 2.5L Merc Rochester Carb too high WOT?

As far as the coil, check the voltage at the + side of the coil. If it reads about 9 volts with the key on, it has a resistor wire, and it's good to go. If it reads battery voltage, you will either add an external resistor or locate the original wire in the harness. With points, you have to read less than battery or the points will burn in short order. The coil itself is a cheap fix. Any auto coil that is configured for points will work. 25 bucks tops. The high vibe coils are great but not necessary IMO.

 

[pigrge]

Re: 2.5L Merc Rochester Carb too high WOT?

High Vibe coil? Well I went and got me a new coil this morning and it was 41 bucks at NAPA, but ohh well. Still has an issue with reading much higher than the tach, I get about 4 thousand at half throttle. What is going on here?

 

[pigrge]

Re: 2.5L Merc Rochester Carb too high WOT?

I just went out and checked my dwell with my dwell meter and the new ignition and it says 89 without even cranking the motor. what is happening?

 

[Benny1963]

Re: 2.5L Merc Rochester Carb too high WOT?

how is your boat running good top speed listen to your motor you would know if your turning a high rpm compared to 3000
b1963

 

[pigrge]

Re: 2.5L Merc Rochester Carb too high WOT?

Well I have never had a boat with a 4 cylinder, but it seems to be running right where I think it would run. I switched props this weekend before the starter gave out and it ran pretty well, actually that gave me another four hundred RPM on the boat tach to get it to 4200 which is right at the bottom of the suggested WOT range. Thanks!