415stinger

Re-post from July 30. First post disappeared???

New to me 1987 41.5 foot Chris Craft Stinger (12,000 pound boat dry), TRS w/ Mirage props (unsure of pitch), I replaced the 454 420 HPs with new 502 415 HPs GM crates. Hirel (now Holley) 1000 CFM MPFI with 36 lb injectors.

Boat runs great up to 4200 RPM which is half throttle (secondaries still closed). from there to WOT I get maybe 200 more RPM.

1. Are the props overpitched?

2. If so, how many inches should I take out to get to the desired WOT RPM?

3. What would be the desired WOT RPM for this setup?

Thank you in advance.
Those who replied to the earlier posting, would you mind replying again? The replies disappeared when the post disappeared.

mmwalters

I don't know what rpm you should turn but that is the way it will act if over proped. You need to find out what pitch and gear ratio you have now and speed you are running for better recomendations. Pitched stamped on the prop gear ratio sticker on the drive.

formula377

What else have you found out?

throttleup

MMwalters is dead on. We need to know what pitch you have now.

I imagine those motors should run about the same as a 502 mag, about 4900-5000 for peak performance.

What speed are you getting at 4200?

Matt