1974 135 hp performance

[ezeke]

Re: 1974 135 hp performance

The timing on that engine may be low. That will affect it's overall performance. There should be a factory label on the airbox which will indicate the max degrees of timing at 5000 rpm. (It should probably be set around 28 degrees.) You should verify the timing when running it and set it according to the original factory service manual.

The full throttle spark advance on the 1973 and 1974 135HP V4 was and is 22?. The throttle pickup is 4?.

The full throttle spark advance on the 1975 and 1976 135HP motors was and is 20? with full throttle pickup of 4?.

See Factory Manual and SB#2004.

 

[N Wolf]

Re: 1974 135 hp performance

I tore down the carbs today. Theres nothing in there! The only things to clean are the needle and seat and the orifices to the jets, and they are about 1/6" diameter. Nothing was dirty or clogged. The needle for one of them was sticking a little but if that were the problem I would only be running on two cylinders. I should be able to notice that plainly rite? Also my plugs are black with carbon. I dont remember what the black carbon means on a plug. I put new ones in it today. I had good spark TO the plugs but that doesnt mean the plugs had good spark. I am going to run it again tomorrow and see if its any better.

 

[ezeke]

Re: 1974 135 hp performance

Carbon build up on all of the plugs usually tells you that you have incomplete combustion. This can be from a variety of reasons among which are:

Lugging the engine;

Running with the wrong spark plugs;

Running with the cheap oil;

Running with no thermostat or a failed thermostat;

And, not disabling the automatic choke.

A complete de-carbon treatment followed by Carbon Guard in all of your fuel will help. Synthetic blend TC-W3 or full synthetic TC-W3 will help.

Make sure that the automatic choke is not enabled, it will cause the engine to pull a too rich fuel/air mix. Like a lot of SBs in that period, this problem is understated; if the thermostat is not functioning perfectly, the temperature switch that controls the automatic choke will stay closed, cause the chokes to close, and foul the engine.

 

[N Wolf]

Re: 1974 135 hp performance

Thank you very much for the info. I think the auto choke has bean removed judging by the atachment you sent. And my choke solonoid is not working anyway. I actually have to climb back and choke it manualy. I use synthetic. But I have only put about 1 hour on this motor since I got it and the plugs were already bad then. I was hoping that maybee the plugs were causing the motor to lug rather than the other way around. The motor came off of a big 19ft ski boat and had a 13x19 prop on it then. That should be fine for my boat but I doubt its a good idea with that monster pulling a skier, witch they did alot. At any rate I am going to the lake with it today with all new plugs and clean carbs. Hope it works out today.

 

[N Wolf]

Re: 1974 135 hp performance

Ok, I took it out taday and got it up to 40 at 5000rpm. However it would not get itself on plane with it trimed all the way down and the fin on it. I have a badly damaged 13x15 and I think Im going to try to run that tomorow. I dont have a clue whats going on with this thing but I need it to be able to get on plane with 2 adults and a livewell full.

 

[N Wolf]

Re: 1974 135 hp performance

I went out again today only this time I ran a 13 3/4x15 and it shot out of the hole with three men and all our gear. Top speed was the same at 38mph 5600 rpm. What do you think? I think I should run a 17 but I dont know what diamiter, 13 1/4?

 

[ezeke]

Re: 1974 135 hp performance

I went out again today only this time I ran a 13 3/4x15 and it shot out of the hole with three men and all our gear. Top speed was the same at 38mph 5600 rpm. What do you think? I think I should run a 17 but I dont know what diamiter, 13 1/4?

If the 15 pitch propeller is as bad as you say, it's hard to know what a good one would do. I could guess that a new 15 pitch prop would allow you to reach 5800 RPM, which should allow you to reach closer to 40.

The gearcase can run a prop with a diameter as large as 14 as long as it does not have to compete with anything bolted to the A/V plate.

Hydrofoils get in the way of the larger props and also create drag, so top end is somewhat changed, especially on any kind of turn.

If you want to experiment, try a Solas Amita 13-1/4 X17. It's not a lot for new aluminum propeller. Some dealers may let you try the propellers.

http://boatpropellers.iboats.com/Jo...n=Both&**********=787329904&*******=450661775

http://boatpropellers.iboats.com/propeller-exclusives/all_promos/

 

[N Wolf]

Re: 1974 135 hp performance

I was planing on getting two props, a 15 and a 17. I like to ski and that 13 3/4x15 will pull stumps. I want to get a 17 cause I need to get my top end up to were I think it should be. As I think this is gong to turn into a prop discusion for the time being, I am going to start a new thread in the props forum.