Offshoreonly.com - engine guys,,,build 468 won't run out

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I didn't do any of those things,,,,,,,but why would it peak at 4000, with 1/4 throttle to go,,,,,,,carb is set up with the standard jets and power valves that come with the holley 850 marine dp,,,,,,,,flow meter says around 23 gph at wot,

removed choke complete

not a carb guy, I took it apart, and blew out everything, maybe I can borrow another carb to try,,,,,,,what would be a next step to try with this carb ? great power from 3 to 4k, then its like on a rev limiter,,,,,,,with 1/4 throttle left

Are you running a rev limiter?

Quote:

Originally Posted by phragle (Post 4707114)

So you changed heads cam compression exhaust and ignition and reused carb. Did you tune the carb to the new motor on a dyno,? Checked afrs? Plug chops at various rpms and loads ? I keyed in when you said the carb worked great on old motor, this motor is a completely different animal

Ok, found the deal yesterday.
My son and I put it in, beautiful day, calm Lake Erie for a change. We drove around, topping at 4k, 3/4 throttle. Started checking everything. Fuel pressure, throttle, ect. ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,rewind,, ,,,,,,,,,,,
Back in the spring My buddy climbed in to set the timing , I told him 36 degrees. He is the most careful , ocd , accurate person in the world, so I never doubted it was correct. Yesterday, I climbed my fat self under there to check it, and guess what ? It was at 24 degrees full advance. So, I reset it, off we went, and it went to 4700, rpm ,,,I'm holding it there, playing around with the trim,,,,,,thinking about prop pitch,,,,and,,,,,,rattle rattle, power loss, pulled it back, clanking at idle,,,,still had oil pressure,,,,shut it down. Hello Boat US ? Lesson learned, do your checks yourself,,,,,will advise after I pull it if something broke, or my engine building skills. were lacking, or my machine shop failed me. It should run 4700 all day, all forged crank, dimple rods, wiseco forged pistons, ,,,,,,,,,,,,,,,,,

What were you using for a timing light? Are you sure it was 24* all in and that you didn’t bring it way up and into detonation?

Quote:

Originally Posted by Unlimited jd (Post 4711718)

What were you using for a timing light? Are you sure it was 24* all in and that you didn’t bring it way up and into detonation?

That was my thought as well except for detonation from high timing will usually hammer the rod bearings resulting in oil pressure loss.

Hopefully you just broke a rocker, nut backed off, bent a pushrod ect........