could this cause 5.7 not to reach w o t?

[bolo78910]

i am back again , 1987 merc 260 with the extra horse power crankshaft freshly reman from a good source . install a new Rochester carb today, compression test shows mostly 155 max 150 s cold engine. i am still only getting 4000 rpm w o t using my same 16 pitch four blade aluminum. only me on the boat, half tank gas boat only get 25 knots. reason for starting this new thread is because i think i might have the wrong thunderbolt magule , why i read the number on the magule that bolt on the riser and it read 6BO9A8-24 something tells me it should be a 22 instead of the 24 correct me if i am wrong, i fould a older magule in my cabin locker maybe that was the original one that was on the engine and the previous owner replace it, this bos is the suare type.

someone please educate me on the right majule for my engine please.
timing is set at 8bdc right now engine run and sound fine. the boat is a heavy carver montego 26 foot maybe the 5.7 is just too small for this boat, i know i might have to drop all the down to a 15 or a 14 pitch prop to put me where i want.

thanks i will be watching for some infos

 

[Mkos1980]

Re: could this cause me not to reach w o t?

Re: could this cause me not to reach w o t?

Module 24 is fine. Its not that. Extra horsepower crankshaft? I dont think so.. Anyway make sure your secondary butterflies are opening up.

 

[bolo78910]

Re: could this cause me not to reach w o t?

Re: could this cause me not to reach w o t?

lol i mean extra horse power kit was install i hope , i think i gess i will never know, lol right now i could care less as long as i get it running the right way, i just hate to go own to a 15 or 14 pitch. oh well, about those butterfly yes it was open , thanks

 

[chiefalen]

Re: could this cause 5.7 not to reach w o t?

Thats a heavy sucker.

You water logged?

Dirty bottom?

Why not go down a size in prop alot of shops let you borrow the prop to see if it works good.

Maybe you need the valves adjusted on the water.

 

[bolo78910]

Re: could this cause 5.7 not to reach w o t?

dirty bottom ?? no bottom is as clean i just drop it back in the water.

waterlogged maybe, i dont know i dont see any sighns of that . boat has not seen water for five years ha .

one thing i am looking at again , sopose the drive has the wrong gear ratio , i know i sopose to be running a 1.5 0r a 1.47 ratio

can i check with the boat in the water to see what drive i have.

if yes is there a way to do it step by step?/

and yeas this boat is a heavy one rides great going around the Rockaway inlet in heavy seas. last adjusting valve on the water i realy dont know how to do that, but i am a fast learner.

 

[Don S]

Re: could this cause 5.7 not to reach w o t?

You can check the gear ratio by doing the following. Remove the spark plugs so you can easily turn the engine by hand. Put the shifter in forward gear and turn the engine over by hand until you get all the slop out of the system and the prop turns. Now, mark the prop so you can see when it makes exactly one full revolution, also mark the engine so you can see how far it turns. With a 1.47 or a 1.5 ratio, it should take a turn and a half of the crankshaft to get one full turn of the prop.

Have you tried hooking up a 6 gal. outboard tank directly to your engine to see if you get full rpms?

 

[bolo78910]

Re: could this cause 5.7 not to reach w o t?

thanks for the come back don , i was hoping you would lol.

ok i will try your tips on finding out the ratio, now the fuel tank inside this one is clean as a whistle as far as my eyes can see, i took off the fuel sender ,shine my flashlight in . it is a aluminum tank when i just bought the boat i had siphon all the fuel out from day one, if you tell that dosent means nada, i will try the extra fuel tank method.

don this is what happen when it reach 4000 rpm i still have more throttle to go, when i push it, it just make more noise/reved no more speed, like it is govern to stop at 4000 rpm. your thought.

i want to load up with all the tips i can get for this weekend because i will be at the boat yard trouble shooting before i perchase a 14 or a 15 pitch prop. thanks guys