What do you think about this?

[victorc1]

On July 17,2009 I bought a 1996 Monterey 180 SCR with a 3.0 LX Mercruiser Alpha One Gen II. Before I bought it I tested it out and it ran at about 35 mph according to the speedometer. I changed the gimbal bearing, impeller, seals, U joints, spark plugs, wires, distributer cap, rotor, thermostat, alternator and rebuilt the carburator. (By the way I learned all this from this forum). Now when I run the boat it only marks 25 mph. Also I changed the propeller, it had a 21 pitch and was in bad shape, I put a brand new 19 pitch. It seems to run pretty fast and the motor runs very well. Could there be something wrong with the speedometer?

 

[HT32BSX115]

Re: What do you think about this?

Pitot speedometers are notoriously unreliable.

Try GPS before you decide if you have a problem.

 

[victorc1]

Re: What do you think about this?

Gps?

 

[HT32BSX115]

Re: What do you think about this?

http://www8.garmin.com/aboutGPS/

 

[sbbamafan]

Re: What do you think about this?

How many RPM's were you turning with the old prop? How many with the new prop?

 

[victorc1]

Re: What do you think about this?

How many RPM's were you turning with the old prop? How many with the new prop?

RPM gauge doesn't work

 

[cr2k]

Re: What do you think about this?

Well of all you did, you did do one thing that will effect your speed. So you need to put the old prop back on to have a base line now.

See if it runs any diff after all the work using your old prop. so you have a base for comparison.

 

[Alumarine]

Re: What do you think about this?

Get the tach working - it's more important than the speedometer.

 

[victorc1]

Re: What do you think about this?

Where do I connect the tachometer wires on the motor?

 

[indy440]

Re: What do you think about this?

buy a cheapo tach from pep-boys or the like and it'll come with instructions how to hook it up. Its very easy.

 

[Maclin]

Re: What do you think about this?

Normally the tach gets power to run and light up from the dash panel wiring. The signal wire is normally brown and connects to the negative side of the coil. It should already be in the engine harness right around where the coil wiring is.

There might be a reason it is not hooked up, sometimes tachs can short internally and ground the signal wire and you will lose all spark.

I agree that the tach is more important than the speedometer.

Normally you would not lose 10 miles an hour with just a 2 inch drop in pitch, but you can sure over-rev the engine with a drop like that if it was close to top RPM before the change.

 

[victorc1]

Re: What do you think about this?

Ok I'll work on it later, just got out off work.