Bassboat prop selection...

[Superdave]

Running a longshaft oval port 2.4 carb with 1.5 exh. 2.1 xfer & intake, 125psi x 6, WH-28's w/ 0.096 & 0.098 jets, elec fuel pump @ 5.5 psi, exh bucket out, holes in bottom of exh hsng, 10" manual setback, 25* max timng, 4* primary, Boyensen 5 petal 2stage, opened cages, on a Hydra-Sport X-270 (17'8"), 2:1 LWP. I have a 28 chopper. IF I raise the motor high enough to blowout to get over 3000 rpm to get in the power range, I have zero or very little positive trim to raise the nose, if I lower the motor enough to get nose trim back, it's dog out of the hole. It will turn up to 2300 and just sit there. Doesn't seem to miss, but has the low speed to high speed switch over blues. I tried a 27 Yamaha & 23 Laser II through hubs, won't plane, gets to 2300-2500 and goes BBBBLLLLAAAAAGGGGHHHHH or however it sounds. Checked all plugs, wires, timing light on all 6 is steady at all rpms. Can't even find a "sweet spot". If it does plane off with the 28, it stands straight up and turns up to 3000. Goes a ways and I have to work steering wheel back & forth to break over. Just before it breaks it jumps to 5000 & blows out. After it breaks over, it falls flat on it's face and drops to 3000. I have to trim the hell out of it to get it to lift. I can turn the 28 6600 after about 100yds. Need some advice. I do know that the high ports will cause some of this, but I find it a little hard to believe it runs THIS BAD.
Thanks to all you great guys for your advice,
Dave

:confused: :confused: :confused:

[Rickracer]

Have you considered one of these? Might help....:cool:

[NPK2003]

Just got my Ally 2003 / Promax back the other day from RP. Motor has similiar mods and initial prop bolted up was 28 TX-4. This is a heavy "fishing Ally, so I do think it will relate to most bass boat hulls. (Ran with 3 BIG batteries, T. Motor, 25 gal. gas, anchors and 500 lbs of passenger &driver for the data below.)

I dug out my trusty 26 Pitch, small hub Throphy and slapped it on. WOW! What a COMPLETE difference. Holeshot actually "shoots" boat on plane and top end comes on strong due to bow carrying nature of the Trophy prop. A RE-3 29 Mazco might work as well and provide more top end but steering torque will be noticeable.
A 28 Throphy and large hub 26 throphy do NOT work as well as the small hub 26. Also, this prop seems to run best about 3/4 " below pad. There are a lot of those props out there. Maybe someone close can let you try one. Good luck
PS: The TX-4 is going on the STV Euro for a workout this afternoon.


:D