Let me introduce myself...and ask some questions too

[emilime75]

Hey all. I am new to the forums and this is my first post. I've been reading the threads for a few days and decided it was time to join. I am new to boats and I am hoping to learn as much as I can.

I just brought home a 79 Procraft with a Mercury outboard(this is my first boat ever). I am not too clear as to the power rating or year of the motor and was hoping someone here could help out.

Like I said, the boat is a 79, and the sticker on the motor claims it as a 78. However, according to the serial number on the motor, 4571057, I believe it to be a 77. Also, the previous owner claimed the motor to be a 90 hp model, but again according to the serial, from what I have read, this is a 115 hp model.

I don't know if I am reading the serial cross reference correctly, so maybe someone here can shed some light on the subject. I do know it is a 6 cyl 2 stroke.

Does anyone know where I could view/download a copy of the wiring diagram for this motor? Some of the wiring is rotted and needs to be replaced.

Is this a good motor? What should I be looking for? What should I check before I fire it up or put it in water. Thanks.

 

[emilime75]

Re: Let me introduce myself...and ask some questions too

Anyone?

How can I find out the true year and HP rating of this motor?

 

[Chris1956]

Re: Let me introduce myself...and ask some questions too

The only way to figure out the HP of that motor is to find the part number on the block and look it up in the parts guide for the year that you think it is. Try to match it up. The P/N of the carbs may give you a hint as well, but might be misleading.

Mercs with HP from 90 to 150 shared the same displacement and number of cylinders (6) from 1972 (or so) to 1977. Motors from 90 to 115HP shared the same number of cylinders and displacement from 1978 - 1988.

Someone may provide a wiring diaghram. If you have specific questions, I might have an answer. Aftermarket wiring harnesses are avail fromSurplusunlimited.com, among other places.

 

[emilime75]

Re: Let me introduce myself...and ask some questions too

Thanks Chris for the reply and the info. I have found a number on the block and it is 948-6262. There is a small stamp next to it with a 380 in a semi circle. Do you have a link to a parts guide that might help me?

If the displacement and number of cylinders are the same for 90 to 150 hp and 90 to 115 hp motors, what is it that determines the power output?

I have also found a good source of wiring diagrams that might be helpful to others on the forum...I will post that in another thread.

 

[longjohn119]

Re: Let me introduce myself...and ask some questions too

If the displacement and number of cylinders are the same for 90 to 150 hp and 90 to 115 hp motors, what is it that determines the power output?

It depends on several things, mainly carbs, reed blocks, and port timings

Just like a 350 CID V-8 can have varying horsepower depending on 2 or 4 barrel carb, valve size and camshaft.

However, unlike the good ol' V-8, you can't easily upgrade a 90 to a 150 or 115 by bolting on a few new parts, mainly because you can't easily change the port timings which are done when the block was originally machined

Also I would suggest you buy a service manual, if the wiring is rotted you most likely have some other maintenance you should do and things you should check. Even a 'one size fits all' Seloc or Clymers should do unless you plan on doing a major overhaul, what they don't tell you you can glean from searching these forums or just asking

 

[emilime75]

Re: Let me introduce myself...and ask some questions too

Thanks Longjohn for the info. I found a wiring diagram for the motor and I have rebuilt the wiring harness. Got the boat started last night with a water hose attached. I did not run it long as I am unsure of just how safe it is to run an outboard with a hose for cooling.

As far as the exact year and HP rating, I am still unsure and trying to find out.