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Motor height question

C

Chuckd

Member
Wondering if this would cause my johnson gt 150 to take around 10 seconds to get on plane? Motor is mounted on a 5 inch jack plate, and has a step in the hull. Center prop shaft is about 6 inches below hull and the plate is about inch and half above. Should I raise it an inch?





 
First is engine reaching WOT, Are you trimming engine down"in" to get on plane,then trimming up "out" afterwards. Not sure with jack plate,but cavitation plate is usually level with keel of craft, Was actually thinking engine should be lowered,but i'm not the expert here. Also what is the diameter and pitch of your prop? Did it come with engine,
 
1) If you ski/tube the height is correct...2)If you fish only it needs to come up about 2 inches. RPM needs to be 5500-5900
 
I agree what is your WOT rpm. You can watch how far the waterline is above the cavitation plate when up on a plane and adjust it so the plate is 1/2 to 1 inch in the water. Are you running at higher altitudes?
 
kimcrwbr1 said:
I agree what is your WOT rpm. You can watch how far the waterline is above the cavitation plate when up on a plane and adjust it so the plate is 1/2 to 1 inch in the water. Are you running at higher altitudes?
Click to expand...

No not at high altitude. Wot is 4600, 24p prop and getting out of hole is a sluggish 10 seconds. Fuel system is good, compression is good , ignition is good, everything has been checked but this
 
How long is your boat and have you checked for a water soaked double bottom? Rule of thumb is 200 rpm for every inch of prop theroretically a 22 pitch prop will give you around 5000 rpm at wot. If your hull is dry and the trim angle is good a 19 pitch should bring you up past 5500 and it will pop out of the hole alot faster.
 
4500-5500 for a 1988 150 jonnyrude you want to get it up around 5000 wot with a good load in the boat. Drop the pitch 4 inches and you can pull a couple skiers out of the water easily.
 
If all you do is fish set it for max performance. Trim engine level with hull and take a level and place on bottom of hullojn the pad, it should split the 4 water intake holes. This will put cavation plate about 3-4 inches above bottom and you should pickup RPM. 24 Raker prop need to be dilled if not factory drilled.The GT150 runs better at the 5400-5800 range, this should put you in high 50's MPH. That hull is copy of old Winner boat which is copy of the old 270 Hydra Sport.
 
I raised it an inch just to note the difference. It came out of hole better and 100 more rpm. I posted 2 videos. First shows going to about 4400 rpm and 53 mph GPS. Second is hole shot. In the videos you can't really hear but the engine is loud, and sounds like more rpms than being produced. Also I tried to set idle timing per manual, and it states to set the cam thumb wheel at 7btdc . But the cam thumb wheel makes no difference when I adjust it. I can set the idle at idle stop but not at 7btdc, because it will run close to 2000 rpms. I have it set for 4btdc now at 1200 rpms on the hose and runs 800 rpms in the water. What am I doing wrong?

https://youtu.be/i4ez5nXt9JM
https://youtu.be/GByeudBbv-Q
 
What is the model number of your motor? From what I can find you have three adjustments in this order. After you confirm all the throttle butterflys open exactly the same time you adjust throttle pickup at 6-8 BTDC. To do this you run the engine with a timing light at 6-8 degrees BTDC use the thumb screw to center the first small line on the throttle cam center of the roller that opens the carb the adjust the roller so it is barely touching the cam then check that the carbs just begin to open as the first line on the cam passes center of the roller. You can then adjust idle speed with the idle stop screw you want to disconnect the throttle cable to adjust idle speed and then adjust the cable to fit. You want to adjust idle speed in the water in forward gear.
Recap
run engine at 6 degree before TDC
align line on throttle cam to center of the roller throttle butterfly fully closed
adjust roller so the butterflys just begin to open as the first line passes center of the roller
adjust idle stop screw in gear on the water 600-700 rpm and adjust throttle cable to fit
If you messed with max spark advance confirm it is correct.
http://www.marineengine.com/parts/j...Evinrude&section=Throttle+&+Shift+Linkage
Your idle speed adjustment is #17 in this diagram.
 
kimcrwbr1 said:
What is the model number of your motor? From what I can find you have three adjustments in this order. After you confirm all the throttle butterflys open exactly the same time you adjust throttle pickup at 6-8 BTDC. To do this you run the engine with a timing light at 6-8 degrees BTDC use the thumb screw to center the first small line on the throttle cam center of the roller that opens the carb the adjust the roller so it is barely touching the cam then check that the carbs just begin to open as the first line on the cam passes center of the roller. You can then adjust idle speed with the idle stop screw you want to disconnect the throttle cable to adjust idle speed and then adjust the cable to fit. You want to adjust idle speed in the water in forward gear.
Recap
run engine at 6 degree before TDC
align line on throttle cam to center of the roller throttle butterfly fully closed
adjust roller so the butterflys just begin to open as the first line passes center of the roller
adjust idle stop screw in gear on the water 600-700 rpm and adjust throttle cable to fit
If you messed with max spark advance confirm it is correct.
http://www.marineengine.com/parts/j...Evinrude&section=Throttle+&+Shift+Linkage
Your idle speed adjustment is #17 in this diagram.
Click to expand...
Model # j150stlcca . If I move idle screw it changes idle timing. If I move cam thumb screw it does nothing but move cam

 
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Engine idle is controlled by spark advance the throttle butterflys are fully closed. The thumb wheel controls the position of the throttle cam. You want the throttle cam to begin to open the butterflys at 6-8 degrees before TDC that is called throttle pickup it puts the spark advance in sync with the throttle butterflys in the carbs.
 
Once you get the throttle pickup correct I imagine it will just jump out of the hole from the videos. Dont be gentle just goose it quickly from idle speed to full throttle. You can get the throttle pickup exact with a alligator clip and a straight wire about three inches clamped it the alligator clip and then clip it to one of the throttle levers on a carb that will tell you exactly when the carbs begin to open you want them to begin to open as the first mark on the throttle cam passes center of the follower roller that opens the carbs.
 
kimcrwbr1 said:
Once you get the throttle pickup correct I imagine it will just jump out of the hole from the videos. Dont be gentle just goose it quickly from idle speed to full throttle. You can get the throttle pickup exact with a alligator clip and a straight wire about three inches clamped it the alligator clip and then clip it to one of the throttle levers on a carb that will tell you exactly when the carbs begin to open you want them to begin to open as the first mark on the throttle cam passes center of the follower roller that opens the carbs.
Click to expand...

Are the joints that go to from metal rod to the cam supposed to wiggle and be loose
 
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