no power
 

hit some rocks 2 weeks ago,had to pull the motor and replace the coupler,transome plate and out drive.picked it up from the dealer put it in the water and the idle was low.adjusted idle and boat will hardly plane out and only pulls 37-3800 rpm.could something have happened to the motor when i hit the rocks?not really skipping or missing just no power.454 mag carb

is your new drive the same gear ratio as the old one?

indeed sounds like a drive ration issue; years ago a merc dealer redid a drive for me; parts were mislabeled and drive ratio was way off- check this first- good luck - jeff

they ordered the same ratio 1.36 but i wonder if the internals of the old where changed.even if it was a 1.50 i don't think i would be down 1000 rpm

Also make sure you check the prop size and diameter. Just because the drive says one thing it could be another! We just went through this with a brand new Black Thunder. Sticker said 1.5 and turned out to be 1.36.:angry-smiley-055:

Let us know what you find.

john

Did you check the timing?

gonna check timing and compression today.talked to the guy that did the repair and he said he never touched the distributor so not sure why the timing would be off but i will check.just thinking if that sudden stop of the prop my have twisted anything or did it bounce on the rev limiter and damage a valve or something.the prop i had on was a 23 and this is a 25 but i pulled this prop 4800 rpm 3 weeks ago

A 25 pitch prop is pretty big for a stock 454 Mag.

i will try another 23 that i have but no way is that gonna give me back 1300 rpm.if i pulled the 25 3 weeks ago i should be able to do it now and i added emi exhaust since then.

just checked compression and timing no problems found.starting to think its in the drive.could it be that far off?

Could be! I have seen it. Generally the next size up in prop will take away 300 rpm. If the ratio was off that would another 500 to 700 rpm.

John:D