What are the specs. on your engine.....blower,N/A ,compression ,cam lift and duration,Cubic inch,crank size,rod length, gears, prop size and boat wt.

38 scarb, weight full, approx 11000. engines = mild 582". 600 @4500. 9.8 compresion short deck BBC.. Cam is small 560 lift. Small oval port heads.

Next test run I am putting in 18degree bushings and setting springs for full advance at as close to 2000 as I can get them. I will set initial timing at 16dgress. This should advance it to 34. I think this set up will get me closer to where I want to be.

The reason for 64 questions is relative to "lugging" your engine .

You never stated the gear ratio or prop pitch. However,at 600 HP one might assume the ratio to be 1.68 gears w/a 28 or 29" prop for 11,000 #.

To be on the safe side,possible to run 87 octane from time to time knowingly or unknowingly and reduce risk of detination I would start at 16 -18 *and curve to 3500 RPM for "all in" 34*

I have 1.5 gears and 26 pitch props right now, but that is all subject to change when I get engines all dialed in.

I was thinking 3500 for all in also, but a couple local guys were telling me to have it all in before boat got on plane.

Right now boat planes right at 2500-2800. This will change obviously with tuned engines and bigger props.

Your local guys may have a good idea ........What do I say ..

Incidently, a 28 " prop w/1.68 gears = 17.26 and your 26 "w/1.50 = 17.33 .....both combinations are very similar....Some feel a 30" prop is Beta and work from there.

Last,my suggestion encompassed working with a big bore,thin wall stroker 9.8 block w/oval heads .

Good Luck !

Thanks, we are real close. I have a bigger problem right now and will tell you in a couple weeks how your suggestion worked out.