WOT RPM ???

[Wetter the Better]

Does anybody know or have a sugg on WOT RPM for the Merc 260 with a Aplha 1? Im running 57.3@5300 with 19 pitch prop should i go with a 21 instead?The boat really pulls onto plane know this is after a head change was running 52@4500 ,can get more mph with a timing light and a good carb.My set up is all stock 350 with a set of warmed over Dart heads w/64cc,Performer intake a edlebrock 600 carb yuk i know getn a holley just need sugg can ya help???
Thanks
And by the way im still running a alum prop to i will get stainless after i fig which i will get 3 or 4 blade
[ June 25, 2003, 01:51 PM: Message edited by: Wetter the Better ]

[Ian]

I'm running a merc 350 (I believe it has 275hp) with an alpha1 outdrive in 21ft closed bow. With two people in it I'm getting 60mph out of it with a 23 pitch prop at about 4800rpm's

[Wetter the Better]

The boat is a 85 chaparral 235 looks like a Nova 23about 4500lbs
[ June 25, 2003, 02:50 PM: Message edited by: Wetter the Better ]

[bordsmnj]

Ian:
I'm running a merc 350 (I believe it has 275hp) with an alpha1 outdrive in 21ft closed bow. With two people in it I'm getting 60mph out of it with a 23 pitch prop at about 4800rpm's just outa curiousity what gear ratio are you guys runnig?

[Wetter the Better]

My ratio is 1.50

[bordsmnj]

5300 rpms out of a "stock" merc 350 is A LOT of rpms isn't it? if i were you i'd just find a prop one size bigger and see what it does. what year is your motor?
come on merc. guys show your selves

[Zuumer]

If you can let me know the year and serial number of the engine I can check for you. Basically a 5.7L (350CID)Alpha 1 is rated at 235 hp, has 9.1:1 compression, and an rpm range of 4200-4600. The 350 Magnum (350CID) Alpha 1 is rated at 250hp, has 9.3:1 compression and an rpm range of 4400-4600. Timing should be 8 degrees BTDC for each.
In any case you need to go higher on the prop pitch to get the rpm's down within range. One inch of pitch equals approximately 200 rpm.
Hope this helps,
Ron

[Zuumer]

Typo on that last rpm range for the 350 Magnum. It should be 4400-4800.

[Wetter the Better]

At the begining of last year i replaced motor with a new GM crate when i worked at the dealership,and put the Dart heads on last week,had out lastnight with more tuning it ran 59.1@5500 with same prop.Im also seeing alot of 4 blades on performance boats any runn one and do you like it over a 3 blade???
thanks Stan
[ June 28, 2003, 07:50 AM: Message edited by: Wetter the Better ]

[carreraelite]

I had a '89 Carrera with a stock 270hp 5.7 alpha. It originally had a 14.25X19 aluminum three blade. I switched to a 14.25X22 stainless steel four blade. I found the four blade to give the boat more bottom end and midrange. It also made the boat drive better!!
[ June 28, 2003, 03:13 PM: Message edited by: carreraelite ]