Lighting comet 7.5 hp 75

[bigjohnson]

1973 7.5hp mercury.
Are these motors known for reliability or do they have any
design issues?
I can get one really cheap and it looks like it's never been
worked on.
Rock solid and heavy.
sn 3730439

 

[timguy]

Make sure of good lower unit, John.....they like to exchange gear oil for water.

 

[bigjohnson]

Yea I noticed there was no FILL drain screws.
What's up with that?
How do they fill and drain them?

 

[racerone]

Well there is a drain screw.----And a smaller vent screw.----look carefully.----Install a new impeller before launching the boat.

 

[fitz73222]

1973 was the year of the Phasemaker ignition system, it can be an expensive system to repair, check to see if it has spark.

 

[bigjohnson]

Well I ended up trading for this motor so I have no money in it.
The wiring was completely shot so I rewired it. Checked for spark
And it sparks just fine. Also the lower unit had stinky black oil
in it and no water. Spent lots of hours cleaning and repairing
failed parts but today it starts easy and idles perfect and has a good water
stream.
The worst issue was it had hard grease and dirt everywhere.
Of course I installed a new impeller.
Right now I'm fabing a reverse lock wire. Also made a shift
lever since this one was broke
The wires going to the threaded stud for the points
was a challenge as well but it's all new now.
Heavy but I think it's a great motor.

 

[racerone]

These older motors are actually not that heavy.

 

[bigjohnson]

Yea
I also have a 1980 7.5 and I noticed a slight difference
but not that much. Once on the boat I really does not
matter.
I would not hesitate to get another one.

 

[racerone]

Some earlier models had a heavy aluminum ( never break ) cowling.----Then they went to some lighter plastic material.------Cheaper to produce and well-----Just cheaper.

 

[flyingscott]

Check the wiring. Mercs of that era are notorious for the wiring falling apart.

 

[bigjohnson]

Yes this 1973 has a TANK for a cowl. It will never break.
And the wiring was indeed completely corroded but I took my
time and rewired it and it starts and runs great.
Just hope these points last....they don't seem to be cheap.

 

[Wentworth603]

I have a mercury comet lightning and they pulled the serial tag off and idk how to figure out the year or hp

 

[racerone]

Post picture of cowling if original graphics are on it.

 

[Wentworth603]

It does say thunderbolt ignition, but it doesn’t have any of the numbers on the cowling, but it is the blue

 

[Wentworth603]

Post picture of cowling if original graphics are on it.

I can’t get it to upload it says the file is to big

 

[timguy]

Hi. You have to reduce photo size to under 1K. Then it will work.

 

[timguy]

I think the blue highlight began in 72 or 73 and ended in the early '80s perhaps all the way to 83. I don't think the Tower of Power went blue until 73.

 

[fitz73222]

Blue graphics started on all models in 1972 and ended in 1983

 

[timguy]

So then 1983 was the last year for the blue?

 

[fitz73222]

Yes, 1984 and 1985 were the brown and gold banded models, 1986 up were variants of red, silver, gray decals for domestic engines.