Acme 431 Prop

Hey guys,

I'm looking to buy an Acme 431.

3 Blade, 13 X 13, LH, 1" Bore

Let me know if anyone has one laying around they'd rather see on the water!

Cheers

Would suite mine just fine.
Get two

Going on a 351W with GT40p heads, custom Comp Cam, Edlebrock intake, etc. so the old stock Federal isn't going to cut it. I'm also now considering the Acme 475 (just a little less pitch).

It an '88 Ski Supreme (If I had my choice it would have been a Nautique, hands down haha). But yes, 18.5 feet.

Right now with the stock 13x13 Federal at WOT its spinning 5300 RPM with only a top speed of 41 mph. So I figured the Acme 431 or 475 CNC'ed (with more surface area and therefore 'more' pitch than the nonCNC'ed stock) should drop the RPMs back down into the 4800 range with a higher WOT speed. Where as the stock-to-Acme comparable 541 would probably keep me at those higher RPMs. Thoughts?

Well we've got too much ice to make that happen now. But I've been getting the itch. So I'm open to finding a 541, 475, or 431 and maybe I'll do a whole test series and write something up. I can borrow a stock 13x13 Federal/Michigan no problem. So if anyone has any of these three, let me know!

I agree with Timmy and Eddie. The Chevys like to spin a few hundred rpm more than the Fords and Eddies set up is pretty stout. With the power range you are pushing even with a stock 13x13 you should be seeing a much higher speed at that rpm. I vote junk original 13x13. It would probably be a hole shot turd with a 431 on it.

I have a new 541 on the shelf I ordered for a guy I can try to make you a deal on.

The supreme isn't a slow hull I think my uncles stock 240 horse 87 is good for about 42-44 or so I assume you should be seeing a lot more speed than that. Confirm with GPS and Tach.

Geez, If you're only seeing 41 out of it with those mods and at that RPM, I just envision that prop being twisted like a pretzel and have only two of the three blades left on it. I'm surprised you didn't have any vibration.
Even in stock form that boat should easily see 42-44 or more like Zach said.
Was the GPS a real GPS and not a cell phone app? The Cell phone apps are also junk. You need to use a real GPS.
You should also try and verify the tach. See if you can borrow a shop tach from someplace.

Like Tim said, see if you can borrow a known good 13x13 federal from someplace to get a good baseline before you start swapping props. Then make sure it has a really good tune with the stock prop. Then you'll really know what the new prop does for you after you change it out.

You have to eliminate a bad prop, bad GPS, bad tach and a bad tune (or any combination of all the above) before you can get the best performance out of those mods.

Definitely keep us updated.

More info needed. What prop, boat, WOT RPM and speed were you getting in stock form? Any high altitude running?
What kind of watersports are you pulling?

The '85 2001 Nautique came with a 14/14 OJ prop when I bought it. It topped out about 4200 rpm wot and gave me 45mph or so measured with a gps. 700' above sea level here where we tow all kinds of toys and ability levels off of the classic tow loop on the stock pylon. It pulled pretty well but was not running reliably. The main reason for the rebuild is nagging little problems that keep popping up.

541 is a LH 13x12
540 is a RH 13x12
543 is a LH 13x11.5
542 is a RH 13x11.5

Yes, you made a grave error.

So with the Acme 475 on my boat, I get 46mph at WOT spinning 4700 RPM.

Turns out the 'stock' prop I had said 13x13 on it but once I got it off, we all looked at it like whoa that's small. Its roughly only 11" in diameter and the blades are not radially symmetric at all. But the Acme... yes! She's so smooth with the Acme.

I bought the boat to restore it completely and rebuilt the engine, so it was a true mystery prop. Could have been a couple reconditionings later