[sanukc]

Originally Posted by Reulandjr

Each 1" drop in pitch increases RPM by about 200, so if you're really running at 3500 you should be running at about 4500, but I can't believe you're actually running a 19" and gettingn3500 RPM. CHECK it again, but my 222 with a 350 mag mpi came with a 19" prop and imwas turning about 4500'RPM

I verified it to make sure it was a 19 prop. Attached is a pic. I wonder if it was because it was fully loaded with 5 people with a full tank of gas. photo.JPG

[sanukc]

I tested it again today with just my wife and I on the boat with a full tank of gas. WOT was 34mph @ 4000 RPM. Cruising was at 24mph @ 3000 RPM. Both speed measurements on the speedometer since I don't have a GPS yet.
Sanu

[voodoo]

My new to me boat, Davanti 225, 5.7 had a stainless 14x19 3 blade. ran poorly and had a hard time getting on plane. A couple of time she wouldn't. 3 people and a fat dog full fuel load. 4200 rpm max at 42 mph.

New plugs, one was much darker than the other 7, new cap and rotor. New 14x17 4 blade.
Whole different boat. Planes in a couple of seconds, reaches 4600 rpm at 45 mph.

Question, what is the red line of the motor, as she will continue to gain revs past 4600 rpm with the 17 inch prop?
Gonna try the 19 again, maybe buy an 18.

[darkcalling]

Red line most gm engines is 5 grand stock the 496 I think is 5200 your wot should be between 4000-5000rpm 4600 would be a safe place to be going much over you are near the limit.