1972 Mercury 800 new owner Little POWER - Why?

[BoatingVermont]

Hello Everyone.

I am new to Iboats.com. It is great. I am pretty new to boating. I purchased a 1974 Glastron V 140 with a ? 1972 Serial Number # 3308960.

A friend helped me rewire the whole whole unit as a previous owner must have had an fire and some of the wires were pretty burnt to the point wires were sparking against the engine.

The engine sounds great when I run it with rabbit ears. In the water, however, it has very little power. I bought an inner tube thinking I could pull a friend behind but when I tried it the boat did not really get up and go.

I thought with an 80 horse I would be able to cruise around pretty good.

An thoughts or suggestions?

Some people locally told me that because it is so old back then 80 horse is not the same as an 80 horse today. I did have one other boat in the past that had a 20 horse on a much lighter boat and I move pretty good.

I look forward to your thoughts and suggestions.

Dirk - boating in Vermont!

 

[Chris1956]

Re: 1972 Mercury 800 new owner Little POWER - Why?

Dirk, That motor is quite powerful. You will easily pull a tube on an 18 foot boat. Your motor is obviously sick. That motor should have a distibutor, so you need to check for bad plug wires. A compression test is first up. All cylinders should be 100+PSI, and within 15% of each other. If so, the rest of the motor may be fixed.

Run the motor on the muffs. Check the plug wires to see if any arc to ground. If so, unscrew them from the dissy cap and replace them. Try vintagemercs.com for these. Inspect the wiring harness for bad insulation. If it needs replacement try Surplusunlimited.com for these.

Post back with the results.

BTW that motor is equivalent to a 75HP motor today, so it should have plenty of zip.

 

[Bob_VT]

Re: 1972 Mercury 800 new owner Little POWER - Why?

Hello neighbor! Welcome to iboats!

The 80 is a great motor and just might need a touch of maintenance. Has it been de-carbed recently? What about a lync & sync?

The other thing I would check is the boat itself. Are you sure you are not hauling around extra weight? The older boats on occasion have water logged foam.

Need help? Drop me a PM ...... I am in West Rutland

 

[rtpassini]

Re: 1972 Mercury 800 new owner Little POWER - Why?

whatever, you shouldnt complain. at least yours starts! mine doesnt (see a few posts down)sorry, thats the jealousy talking.

but yes, you shouldnt have any problem pulling anyone. it should be able to do about 40 mph with your boat.

 

[BoatingVermont]

Re: 1972 Mercury 800 new owner Little POWER - Why?

Hey Chirs.

Thanks for your suggestions. I do need to do a compression test and will check in with the results later. Frankly I don't rember if there is a distributor or not. I did replace the wiring harness. I will be unpacking the boat this week or next.

I do remember that the carboratures were in pretty bad shape and lots of sand in the fuel filters. My friend cleaned the carbs and filters but I don't know how good a job he did. I will need to make a priority/order list in which to tackle some of these questions so I don't make a ton of extra work for myself.

I really appreciate your answer regarding the HP equivilancy for I searched around quite a bit and could not find an answer - or got the good old, "well that depends ..." routine.

I just wanted a ball park b/c again, it feels like it is putting out about 10HP - but sounds really great and tight!

Bob's post mentioned something that's been eating at me - if the boat is water logged. For some strange reason I think it is, terribly. I do not know what that translates into as far as overhauling the fiberglass and what is involved but ... I will cross that bridge soon, I'm sure. How does one tell if a boat is water logged - my first thought is to take it on a scale at the local dump. My registration says the boat should weigh in the neighborhood of 700lbs but they are often way of the mark so that is another R&D project - the weight of my boat.

Anyhow, Chris, thank for giving me a running start!

Dirk

 

[BoatingVermont]

Re: 1972 Mercury 800 new owner Little POWER - Why?

Hey Bob.

Great to hear from a TRUE Neighbor.

I am hoping that your reply is more of a reality than the motor being a gonner.

It really looks, sounds and feels like it has low hours on it but I have been wrong before. I have also been very prone to making simple problems and fixes much more complicated than they need to be so ... I need to proceed with caution and lots of expert assistance.

As I mentioned in the post to Chris regarding your thought - I think you might be right about carrying around extra weight with regard to water in the foam. How do I check? Is the foam encased in fiberglass or just under the floor board, exposed?

Once I unpack the boat next week I can start to get into things more.

Thanks,

Dirk

 

[BoatingVermont]

Re: 1972 Mercury 800 new owner Little POWER - Why?

Yeah, I know I should not complain but the thought of knowing that if I just tweaked, cleaned and replaced a few things I would gain about 65 horse and 30 mph is enough to get me seeking out the possibilities. For the fishing that I enjoy doing i don't need much more than my electric troller but to think I could haul around a tube during the hotter summer days .....when I can't seem to get a fish to bite ...... you know what I mean.

Dirk

 

[bucchb]

Re: 1972 Mercury 800 new owner Little POWER - Why?

You have 2 possible course of actions (especially if this is a trigger motor, with a distributer????) and you don't have an accurate understanding of the current condition of motor?.

1) Get a manual, buy a magnetic micrometer to set or check timing, compression guage, Gunk carb dip tank, and volt meter.
Spend about 100 hours trying to figure this thing out. OR

2) Find the best old mechanic you can who really has a lot of experience with OLD MERCs.

You could be an expert at rebuilding cars, motorcyles, MIT grad, etc BUT it takes years of experience to know how to diagnose and fix these complicated beasts.

Mine has been in the shop with a trustworthy mechanic for 3 weeks and I stop by there ever couple of days and it is one thing after another. I have a Masters in Mechanical Engineering.

 

[jeffdjpeat]

Re: 1972 Mercury 800 new owner Little POWER - Why?

i agree with bucchb but some of us cant afford that super qualified mechanic, and look to the iboats forums for help to do things ourselves. there are a lot of great people on here with a ton of knowledge to share.

 

[jeffdjpeat]

Re: 1972 Mercury 800 new owner Little POWER - Why?

after 3 weeks in a shop i would assume you pretty much bought a new motor eh bucchb??