1115 will not reach 5000 RPMs at WOT

[Skippy the skipper]

I am working on a 1115 inline distributored, 1988 that will not reach 5000 RPM at WOT. I have done the link and sync, rebuilt the carbs, checked the fuel pump and inspected everything I can think of but it still will not reach 5000 RPM. Compression is at 125 on all six, good spark on all six with the sparky. Let me give you guys some history on this engine. I am the 3rd mechanic to work this jewel. 1st guy replaced some ignition parts (don't know why or what but he never even checked compression). 2nd guy found low compression on 1 cyl and did a rebuild. I get the boat it dies while put in gear and will not wind up. I also find the carbs had not been rebuilt and were leaking gas horribly when the bulb was depressed. Ok I'm thinking this engine is drawing too much fuel out at high RPM so I rebuild the carbs and do a link and sync. Runs smooth and does not die now. Hooked up my trusty tach to #1 and only get 3800 at WOT, recheck link and sync (21 at max advance at WOT with the timing light) still no go. I have not worked on these distributor mercs all that much, could I be missing somthing? I did the link and sync found here in the forum and it was much better than my manuals. But I still feel that it may be an electrical problem. BTW I noticed a small drop in RPM when I would try and trim the engine at WOT, instantanious when I would hit the switch (possible stator problem)? Any help would be greatly appreciated thanks in advance!!!! Also has the original prop since before rebuild which would let engine reach 5000 RPM

 

[Chris1956]

Re: 1115 will not reach 5000 RPMs at WOT

Skippy, First of all if the motor has a distributor it is no newer than 1978 or 1979. Secondly, the stator plays no part in the ignition system. It simply charges the battery.

I would inspect the plugs. if the number six plug(or any of them) looks brand new, it may be getting "steam cleaned" due to water infiltration. if so, then number 6 is not firing, which explains your lack of power.

BTW- are you sure the prop used to spin at 5K RPM? What is the pitch and what kind of boat do you have? I will also guess you have a 115HP, versus a 1115HP motor.

 

[Skippy the skipper]

Re: 1115 will not reach 5000 RPMs at WOT

Yep 78 1150 aka 115hp, my bad on the typo. Yes all the plugs are new and I have inspected them after a run and seen no evidence of steam cleaning on any of them. As for the prop I can only go by what the guy said. The last guy he took it to is shady enough to have switched props btw. I will have a look at the prop pitch vs boat size. any other ideas?

19 pitch prop, probally a 17-18 ft boat