1984 Mercruiser 140 Rocker adjustment & RPM Issues

First post-
Fist off thanks for everyone here, ive been lurking in the shadows and finding fixes for multiple issues on my boat and in general reading random post to learn more. Bought it 3 weeks ago for 500 non running and so far so good with getting it back up to water worthy.... but ive come across an issue and I cant figure it out. (1984 19' Open bow Citation)

Had it out yesterday and noticed a lil knocking on the high end and im wanting to take the valve cover off and make sure the rockers are all adjusted correctly but cant find any specs.
Looking for any info or links to point me in the right direction, Thanks!

Also when we took it out the boat would idle fine and throttle response was great in N but when it was put in Forward gear and I would give it a lil throttle the boat would hesitate and if I did not bring it back down to Idle it would die. Ive had the Carb professionally rebuilt so I dont think that is the issue, Im going to put new plugs in it today and see if that fixes it because it just seemed like it was either getting to much fuel (but never flooded) or it was not getting enough spark (No idea how old the plugs are and there motocraft). Idle was fine and when It was in N I could rev the hell out of it with no issues but under a load it just did not want to go over Idle, I did manage to get it up to 2300 rpms by adjusting the points but after 2-3mins it started acting up again and ran like crap.


Any info is helpful (Yes I did check the main post about WOT issues but im also having an Any Throttle Issue). Im hoping there is some common problem with this motor that I can check and address.

Thanks!
WhiteTrashSTL

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

Have you replaced the points&condenser?

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

This video should help you with your rocker arm adjustment...

http://forums.iboats.com/showthread.php?t=435011

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

zb- Not yet, just got my new NGK plugs and taking out the motocraft plugs.. if no change ill move on and replace the points/condenser. I was also was told by guy at boat place to check my anti syphone valve on the gas tank to make sure the spring/ball are not rusted up which I will be checking later.

Al- Thanks for video!

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

After the anti siphon valvr inspection check make sure the vent to the fuel cell is un- obstructed this could cause a lake of fuel delivery as well but you might as well replace the points and condensor while your @ it so you have a semi fresh start, Could also be old fuel and or fuel filters and there other possibility could be a shady carb job and or not thourough enough cleaning before re-build!

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

Also when we took it out the boat would idle fine and throttle response was great in N but when it was put in Forward gear and I would give it a lil throttle the boat would hesitate and if I did not bring it back down to Idle it would die.

Click to expand...

Baring the points, plugs, wires, timing and so on.

A hesitation off idle is a lean condition.
Turn the idle mix screw(s) out a full turn and see if that helps. It should and then you can see if you need more or less of this. Also the float level may be way to low.
I see it was a pro rebuild, but......

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

Well the new plugs fixed the RPM issue (took out motocraft and put in NGK) and we had her out running great for a few mins and another problem arose.
While we were out and adjusting the idle/points etc something went wrong with the shift cable, we can idle now in N but once we put it in Gear (Forward or Reverse) she dies instantly, no rough idle no surging just shuts down like we turned it off. Buddy who has done all the work on the boat thus far thinks the cable is messed up so were gonna take it off and check it out.

Also we noticed as well as the other boat we had with us, that the prop does not seem to sit deep enough in the water, its all the way down and it does not plane up when we give it full throttle but we can look over the rear of boat and see the prop spinning and churning water when were 75% throttle, almost like the prop is moving more water then it can take in... no notice is performace loss or anything just something the other boat driver noticed and pointed out to us... maybe the prop is too big? I can take a pic of the prop and post here later along with measurements but as far as pitch Im not sure how I would go about measuring that.

Thanks everyone for the helpful information!

Took the valve cover off and made sure all the nuts were tight, one was a lil loose and that noise also went away once tightened down.
PS: Points/Cap/Condenser and wires were all replaced 2 years ago and look brand new so were not gonna replace them yet since with the new plugs the RPM issue is gone.

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

It sounds like you are having a typical lower shift cable issues. If the shift cable starts to bind at all it will trigger the shift interupt mechanism and turn off the engine.

http://forums.iboats.com/showthread.php?p=1930449#post1930449

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

^ Indeed we were. Figured out that the screws that hold the section of wood the shifter is mounted to worked themselves out of the fiberglass and we were unknowingly rubbing on the inside of the wood panel... no damage done to the wood but the shift interrupt seems to be messed up know. Even though we remounted the wood and the shifter is free and easy to move forward and back the shift interrupt still wants to hit and ground out once we put it in gear. Tried to adjust and did not work so for a temp fix and the verify the issue we tightened it down so that it cant move and the boat fires up and runs great forward and reverse (out of water on muffs).. gonna hit the river tomorrow and keep a close eye on the shifit interrupt, if it does it again then we will start the steps of fixing it.

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

Lower shift cable bad.

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

Had the boat at yesterday and it was perfect. Figured out why the prop did not seem to be deep enough picked up some debri from the river and it jammed itself up inside where the prop lowers into, pulled it out and everything is all good thus far.


Gonna replace shift cable to be safe.

Thanks everyone for the help. Kudos!

Re: 1984 Mercruiser 140 Rocker adjustment & RPM Issues

Labor Day: Thanks for the advise everyone!