Newby here sorry I'd this has been discussed I'll try to be brief. Bought a formula end last year 223 with 5.7 magnum. Ran good had a bog rebuilt carb took it out worked amazing Rev to 5k . Figured prop was small I'd take it easy. Well not due to rpm but due to huge amounts of rust built up in engine heads and manifold I over heated cooked the engine. Winterized put away.
NOW spring 2021 arrives had a brand new engine built. Different block. I put on new manifolds new risers rebuild carb again new chock Stat new cap rotor plugs . Wires coil seem excellent (msd upgrades) all in starts and purrs like a kitten drop in lake to break it in. Keep my rpm between idle and 3500 ish. And now have 10 hours . Time for a little more juice. So remembering prop and rpm from previous season did some math figure I should have a 21 pitch. Borrowed one to try hit the lake and putt around a bit make sure all is good now wanting to give it some go go juice. I can only hit 4000 rpm max. Play for a bit no change just figured I put to much prop maybe a 19p be better.
So past Saturday hot need the lake need to boat. Through my 17p back on figure I'll be carefully and just enjoy the lake add up few more hours on the break in.. well surprised as I was again.. max rpm is 4000 . Stumped. I've now checked base time make sure it was right on the rebuild. And it's perfect 8 degrees.
So now I'm stumped the 17p prop should have had me over reving like season before and no gain. Only noticeable difference is time to plain .. much faster with the 17. But still no rpm. I should be 4600 to 4800 and 5k won't kill it But not a place to run all day..
Any other suggestions would be amazing help thanks ..
NOW spring 2021 arrives had a brand new engine built. Different block. I put on new manifolds new risers rebuild carb again new chock Stat new cap rotor plugs . Wires coil seem excellent (msd upgrades) all in starts and purrs like a kitten drop in lake to break it in. Keep my rpm between idle and 3500 ish. And now have 10 hours . Time for a little more juice. So remembering prop and rpm from previous season did some math figure I should have a 21 pitch. Borrowed one to try hit the lake and putt around a bit make sure all is good now wanting to give it some go go juice. I can only hit 4000 rpm max. Play for a bit no change just figured I put to much prop maybe a 19p be better.
So past Saturday hot need the lake need to boat. Through my 17p back on figure I'll be carefully and just enjoy the lake add up few more hours on the break in.. well surprised as I was again.. max rpm is 4000 . Stumped. I've now checked base time make sure it was right on the rebuild. And it's perfect 8 degrees.
So now I'm stumped the 17p prop should have had me over reving like season before and no gain. Only noticeable difference is time to plain .. much faster with the 17. But still no rpm. I should be 4600 to 4800 and 5k won't kill it But not a place to run all day..
Any other suggestions would be amazing help thanks ..