Johnson J90TLCNB (1982 Johnson 90 hp with power tilt and trim) Timing Advance Specifications

[RBoyd1971]

If you have a factory manual for this motor, can you see what the advance should be set at when wide open throttle.

 

[racerone]

28 degrees BTDC is the usual WOT setting for the V-4 crossflow.------But timing on these motors is set at the factory for the life of the motor.-----What is your motor doing / not doing ?

 

[RBoyd1971]

I'm planning to do a link and sync. You can tell it's been messed with in the past. At the spot on the stop screw where it's slotted for a screwdriver, one side is broken off as if someone attempted to turn it without loosening the lock nut. It may be correct but I'd like to verify. It has a mid range miss and the carb butterflies were out of sink. Once I synced them, it smoothed out a lot. It's probably ok, but want to be sure. Overall, it runs pretty well though.

 

[ct1762@gmail.com]

do all the coils look to be in good shape, OHM out ok, and have good clean grounds? if it still misses, i'd redo the carbs then look to further ignition tests and pull flywheel to have a good look at condition of stator

 

[RBoyd1971]

I've finally gotten back to this motor and have some observations and would like some thoughts on them. I went and checked the timing at wot, using the Joe Reeves method. It's showing 29 degrees which would be about 5 degrees too far. The set screw has definitely been messed with, so not a total surprise it's off. However, this is more perplexing to me. At idle it's at 5 degrees with the stop against the block. When I move it to where the roller meets the mark on the cam it's running at 15 degrees. Those numbers seem way off from what I've been reading; should be 4 degrees when the roller meets the cam mark. I don't think there is even enough adjustment to get it to 4 degrees. With all that said, I'm going off of data for an 86 90 hp because I can't find a manual for the 82 or the specs online.

 

[RBoyd1971]

I've finally gotten back to this motor and have some observations and would like some thoughts on them. I went and checked the timing at wot, using the Joe Reeves method. It's showing 29 degrees which would be about 5 degrees too far. The set screw has definitely been messed with, so not a total surprise it's off. However, this is more perplexing to me. At idle it's at 5 degrees with the stop against the block. When I move it to where the roller meets the mark on the cam it's running at 15 degrees. Those numbers seem way off from what I've been reading; should be 4 degrees when the roller meets the cam mark. I don't think there is even enough adjustment to get it to 4 degrees. With all that said, I'm going off of data for an 86 90 hp because I can't find a manual for the 82 or the specs online.

I see in the OMC manual, the timing at WOT is supposed to be set at 4000 rpms not when the arm is tight against the stop like the 86 model. The 4-6 degrees when the roller aligns with the mark is correct though.

 

[ct1762@gmail.com]

I've finally gotten back to this motor and have some observations and would like some thoughts on them. I went and checked the timing at wot, using the Joe Reeves method. It's showing 29 degrees which would be about 5 degrees too far. The set screw has definitely been messed with, so not a total surprise it's off. However, this is more perplexing to me. At idle it's at 5 degrees with the stop against the block. When I move it to where the roller meets the mark on the cam it's running at 15 degrees. Those numbers seem way off from what I've been reading; should be 4 degrees when the roller meets the cam mark. I don't think there is even enough adjustment to get it to 4 degrees. With all that said, I'm going off of data for an 86 90 hp because I can't find a manual for the 82 or the specs online.

captain obvious here: did you set the timing pointer correctly with a piston stop tool?

 

[RBoyd1971]

captain obvious here: did you set the timing pointer correctly with a piston stop tool?

Yes, I did and it was off slightly. I set everything per the manual. It was at about 16 degrees when the roller was aligned. Also when the arm was against the stop using the Joe Reeves method showed 29 degrees, so I retarded it 5 degrees. Sure seemed out of whack but I will say, it runs perfect now. This motor looks to be made from about 5 different motors so that could be a clue as to what was going on.

 

[ct1762@gmail.com]

hmm... maybe the incorrect flywheel! they made a goofy amount of different timer base magnet positions.

 

[RBoyd1971]

The only thing is, when the roller is aligned with the mark on the cam and it's set at 4 to 6 degrees, I don't have much room to adjust the idle. It's idling at about 530 rpms and if I try to increase it, the roller will touch the cam and open the carb butterfly valves sightly.

 

[ct1762@gmail.com]

The only thing is, when the roller is aligned with the mark on the cam and it's set at 4 to 6 degrees, I don't have much room to adjust the idle. It's idling at about 530 rpms and if I try to increase it, the roller will touch the cam and open the carb butterfly valves sightly.

ah good observation! Which is why you launch the boat, timing light ready to go, and do the synch n link in the water, with the cam roller loosened and away from the throttle cam, and of course throttle cable disconnected. then do the idle speed, and once that's about 650rpm in forward, adjust cam roller as before.

 

[RBoyd1971]

I figured out what happened with the timing on this motor and thought I wound post an update in case anyone else runs into this. The pickup timing and the wot timing was off because some genius had removed the spark advance rod retainer from the spark advance lever and put it back in the hole from the outside instead of the inside which pulled the timer base forward advancing the timing. I noticed it today and swapped it around. After setting the timing again everything looks normal instead of looking like the timing was retarded to the max. They gave me more room to set idle as well. I should have studied it closer when I seen the timing was way out.