Cool, thanks. Think I'm going to switch to the 8mm cog setup, same as you have, nice stuff. Wow, that stuff adds up quick when you have to peice it together!!! $$$ But at this point I ask myself, hell, why not?

Something isn't adding up on my end. 572cu in., 8.3:1 comp, so 17%, 20%, or 25% overdrive for 5-8psi? Anything over 18% sounds high to me....

I am not an engine builder, nor do I pretend to be, just looking for setup feedback here.....

I would suggest starting with the least amount of overdrive that way you can get a good tune up and then go up from there if need be. especially if this is your first time with a blower engine. Better safe then sorry. Also Boost is just a number of resistance so depending on the size of your engine and how efficient it is will determine the amount of boost it makes.

Boat looks great Mark your going to have a really nice piece when all said and done!!!

Thanks Joe! I can't thank you enough for stepping in and getting these engines straightened out for me!!

Frick, I would listen to Joe on the boost deal... After all he is going to tune my engines in the boat!

You can use this diagram as a refrence point... 570ci 8-9lbs they are calling for 25% OD
http://i1123.photobucket.com/albums/...ps94f8b703.png

Here is the link to the pulley chart

http://www.offshoreonly.com/forums/a...tion-chart.pdf

Mark I've been told more than once on smaller c.i. Motors that chart is a ways off. Did you compare it to your past setup?
Curious if they were closer on 540-572s. Frick your gonna have to overdrive these 420's a bit more to provide enough air for 570+". That's really at the top of their efficiency. Right around 850 I think? If you have the 16 rib pullies now I'd be interested in them if you go to 8mm

Mine was 2lbs low from the chart.... But i really think it was because of the cam they were using... It was crazy huge for a 6000rpm engine.

You've got to wonder what these builders are thinking when you find components that ire so mis-matched for the application.

-We when we first tore dowm my 575SCI's we found solid roller cams similar in size to a 1075 cam, roller liters beating on the spash tray under the intake. (looked like 16 ball peen hammers had at it) and the stock flat fappet valve springs... Also supposed to have been done by an industry 'expert'

Great thread BTW, nice attention to detail and enjoy the updates. Good luck!

Kurt

Jeez.... Im glad its not only me... I think if more boaters started looking into their engines, some of these industry experts would quickly be out of business