3500rpm at wot

[numpux2020]

hi guys long time reader here but first post. i bought a 1986 four winns liberator 211 w a 5.7 litre 260 hp mercruiser. beginning of summer, first few times out it was 4400 rpm at 45 mph.now my max rpm is 3400 at 35 mph...i did a tune up plugs(.044 gap) wires, rotor, cap, in line fuel filter, fuel water seperator, still the same...the boat weighs 3250# with a 21 pitch alu prop, but it had better performance with same hardware...gonna do a compression test, simply caus i m not sure what to do next.maybe the rochester quaudrajet secondary isnt actuating...all else is fine,idles fine accelerates fine.maybe someone can advise , thanks in advance

 

[Bondo]

Re: 3500rpm at wot

Ayuh,... Welcome Aboard,..... Is it a Dock boat, or Trailer boat,..??

 

[numpux2020]

Re: 3500rpm at wot

thank u sir i have been reading your replies to posts for months very knowledgable by the its a trailered boat my pride and joy

 

[Bondo]

Re: 3500rpm at wot

its a trailered boat my pride and joy

Ayuh,... Don's got a Great post up in the Adults Only section titled something like "won't go Wot"...
Check it out....

 

[NHGuy]

Re: 3500rpm at wot

That's weird. Did the top end go away gradually or suddenly? Are you sure it runs OK but just won't spin up to 4400? No missing, spitting, backfiring belching, surging etc?
Does it use the same amount of gas? Try cracking the gas cap to see if it has a clogged or partially clogged fuel vent. Have you put a timing light on it, timing should be 8 degrees BTDC.