Gutless wonder?

[paperdesk]

Hi all!
I have a 1973 Rienell boat (17' trihull) that had a 1973 135hp Evinrude on it. The 'rude died, and I replaced it with a "older" maybe 69? mercury 1100 outboard (110hp).

The Mercury performs terrible on my boat. It takes forever to plane, can't pull a skier, is very slow etc. However, it worked great on the boat it came off of (a 17' v-hull glastron).

I adjusted the trim all the way out and in and it doesn't fix the problem. Any ideas on what could possibly be the matter? I haven't figured out how to attach the tach yet, but it sounds like it's revving as loud as before once it planes. When the motor was switched over we didn't change any settings, just disconnected the cables at the control box and reconnected them again.

Of course 110 is lower horse power than a 135, but that Evinrude had terrible compression one badly scored cylinder, and I'm sure was running at greatly reduced power.

Could it be that some setting got changed,
Is it possible that my heaver trihull needs a bigger engine?
The back of both boats are similar, but maybe the motor needs to be raised or lowered?

Any ideas would be welcome!

Thanks!
Ted

 

[paperdesk]

Re: Gutless wonder?

BTW, The Mercury runs fantastic! It starts easy and idles amazingly well, nothing like my 'rude that wouldn't idle at all unless I had cold start lever way up..

 

[ricksrster]

Re: Gutless wonder?

The tach is impotatant so you can prop the boat correctly. That may be your problem. On your mercontrol, ther may be a plug or a small harness attached it. Ther will be a brown ( or a grey ) wire. That is the send wire for the tach. There will be a white ( or a purple ) wire. That is pos.12v from the key on. That attaches to the ING post on the tach.The black is the ground. If your control doesn't have these wires, attach a wire to the key on post on the ignition switch and run to the IGn post on the tach. Run a wire from either yellow ( or yellow/red stripe ) wire that is attached to the rectifier on the motor and attach to the SEND post on the tach. Set the little switch on the back of the tach to 6p.

 

[paperdesk]

Re: Gutless wonder?

Thanks Rick. I'll go try to set that tach up! Hoping that will help resolve my isues!

 

[tashasdaddy]

Re: Gutless wonder?

were both engine the same shaft link. possible you have a longer shaft motor. anticavitation plate should tbe even or above the the lowest part of the hull.

 

[tmcalavy]

Re: Gutless wonder?

tashasdaddy read my mind. I think you need to adjust motor height and make sure the cavitation plate is even or just above the lowest part of the stern hull. Reason I say so is I had a 73 Merc 500 4 cylinder that pushed a 73 Ebbtide trihull like a scalded ape even though the boat had some foam saturation issues that I eventually fixed. It was a 15 foot trihull with walk-through windshield and that little 50 horse could make it fly, with and without a fin. Finally sold it cause it was too much for just me and the Lab to launch and recover...he isn't very good with a clutch on the boat ramp.

 

[studlymandingo]

Re: Gutless wonder?

My guess is the prop for sure. The 110 should easily push a 17' boat, unless it is severly overpropped. The tach is of utmost importance to determine the performance of the rig. The AV plate height relative to the bottom of the hull is of utmost importance as well, should be just about even with the pad. I used to have a 70HP on a 17' boat that would do 32MPH.

 

[paperdesk]

Re: Gutless wonder?

Thanks for the posts! I discovered this morning that my old tach is only good for 4 cylinder motors, but I have a test tach that should hook in. I found the plug you were talking about Rick, and I'll hook in there. I'm at work now, but will check the engine hight at lunch break if I can get away, and the tach as soon as I can get to the lake. Thanks for all the advice, I'll post with what I find out. BTW, I have a brand new 13 1/4 x 17" prop. That's what it had on the other boat, and what I ran on my 135 Evinrude, maybe it's too big still.

Ted

 

[paperdesk]

Re: Gutless wonder?

I'm also wondering what spark plug is correct for this motor? It has Champion L78V's in it, but a shop said it should be L76V. Any idea which is right?

 

[paperdesk]

Re: Gutless wonder?

I checked the plate height and it looked even. Maybe we're just overproped for this boat. When I check the tach readings, what is normal range for this motor?

Ted

 

[studlymandingo]

Re: Gutless wonder?

That model is not covered in my manual, but I think it should be in the 5200-5600 RPM range at WOT. Closer to the higher end of that spectrum, the better the hole-shot.

 

[paperdesk]

Re: Gutless wonder?

I tried hooking up my auto test tach, and it didn't read anything. Not sure if it's incompatible or what. Thought I'd used it before. Without a tach I feel pretty stuck. Seems a 13 1/4 x 17 is already a small prop, but maybe I could go smaller? I'll look for a tach today.

Ted

 

[Chris1956]

Re: Gutless wonder?

Paperdesk, A lot of 4 and 6 cylinder Mercs shared a tach. The tach counted stator pulses, not spark pulses, and the 4 and 6 cylinder motors shared stators. The best way to know is to find an application for your tach.

Barring that, match stator part numbers using www.dougrussell.com to look them up. An example. My '73 850 (4cyl) and my '77 1500 (6cyl) share all ign. components but dist cap, starter and coil. The coil and starter differences are form and fit, not compatability.

PS I would think your prop would give reasonable performance, but could be have 2 " too much pitch, to be optimal. First things first, get the Tach working so you can know.

 

[ricksrster]

Re: Gutless wonder?

Chris is right about tachs. Set your old tach to 6P on the little selector switch on the back of the tach. It might already be set there. I believe your Evinrude 135 was a 6 pulse stator also.

 

[ricksrster]

Re: Gutless wonder?

The L78V spark plug is just a little hotter than a L76V. I put L78V's in my motor. Some manuals called for L76V and others L78V.

 

[RRaider]

Re: Gutless wonder?

My manual shows 110's in 66 and 67, wot range one both is 4,800 to 5,200. Does not show a 110 in 69.

 

[paperdesk]

Re: Gutless wonder?

Thanks for the great info! I was supposed to have a mechanic friend look at it Friday, but the bearings went out on my trailer half way there! Had to cripple it back home, so I don't know how long it'll be before I can make it back out on the water now! Hopefully within a week if I can find parts. Ruined my axel and hub too.

It seems to run fine with the L76v's, we'll see what happens long term. I noticed that when I use the old beat up (warn down) prop, it seem to plain faster, but when I use the new prop it goes about 5 mph faster top end. Also though, with the new prop it really pulls hard to the right.

Sounds like this motor is a 66 or 67! Almost 40 years old Scarry!

I'll go ahead and keep working on the tach issues, and follow up your leads.

Thanks!

Ted

 

[ricksrster]

Re: Gutless wonder?

Turn the trim tab slightly to the right to stop the boat from pulling to the right.

 

[paperdesk]

Re: Gutless wonder?

I can adjust the trim tab, but I guess I'm wondering why would one prop pull hard and the other not pull at all?

 

[ricksrster]

Re: Gutless wonder?

One prop might be biting the water a little more than the other.