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Throttle cable ?

88 thundercraft

New member
I have a twin 4.3 omc inboards and port side throttle under load will only go to 3500 rpm wide open is this just a cable adjustment if so can you tell me how.p.s. just joined this site and love the information,boaters rock.
 
What rpm's are you able to pull with the stbd engine? First thing I would do is take off the flame arrestor and look down inside the carb (push throttle all the way forward) and see if the throttle plate is fully vertical @ 90 deg, compare with the other engine. Did this engine used to go up higher or did this just happen?
 
If after looking at the carb it's ok then check compression on a warm motor all the plugs out and the throttle fully down.
 
Okay i checked carbs and throttle plate not fully opened at 3500 rpm,also the lever is about an inch and a half difference from stbd lever is this now a throttle cable adjustment if so how to do it.thanks,boaters rock love the advice from you guys
 
Still not convinced that a throttle cable can get that far out of adjustment by itself, This is just what I would do, disconnect the throttle cable at the carb and then see if you can manually open the the throttle plate all the way (90 deg vertical), if so now go push the throttle lever forward all the way, does it now go as far as the stbd? I suspect your problem maybe in the throttle/shifter mechanism? What kind of shifter do you have, the OMC dual binnacle mount like in the pic below?

boatinside4-1.jpg
 
it will go all the way to the top but not the rpms they stop at approx 3500 while stbd gives me full throttle

ok...what goes all the way to the top? Does the throttle plate inside the carb open right up with the cable disconnected? or does the throttle lever itself now match the stbd with the throttle cable disconnected?


This may sound like a stupid question but you didn't change the prop recently on the port drive did you?
 
ok...you told me before that the throttle plate was not fully opened, I'm still waiting to hear if the plate does fully open by hand with the throttle cable undone. If the throttle lever does go all the way now with the cable undone at the carb then there could be a problem with the carb.
 
ok then...short of the cable having a kink in it, was any work done recently where the cables are located? Sometimes something can get jammed up against them like a spare anchor. If not then I would try adjusting the cable at the carb end, marking it first. Make sure the clampo that attaches the cable to the carb is tight as well before starting to adjust.
 
thanks i will try this tomorrow,going to big shute this weekend and would love to have this fixed,other wise i will try a mobile mechanic in lefroy that may be able to help your advise is greatly appreciated.
 
Good luck at the chute, if you're going through it can get pretty backed up on the down side waiting to come back up.
 
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