Prop selection question

Well, here's an update on Mav's prop story as of tonight.

To start with some background info, the boat's a mid 80's 2001 hull with a LH rotating , 400ish HP 454 that he recently bought and has been working on.

His issue is that the boat accelerates well, but if he punches it a 30 mph or so, it's slipping or cavitating or whatever.

He could use a new prop and what he has on it right now is a 13 by 14 LH prop that's somewhat beat up. That's the stamping on the hub anyways



And the key is in the keyway

He verified that the shaft is 1 inch diameter, he mistakenly thought it was 1 1/8 inches and ordered an Acme 425 that'll be getting returned.

His dilemma is ...........what to get

He could get an Acme 431 13 by 13 .080 cup

Or he could get an Acme 1459 13 by 14 .135 cup

I figure either is gonna work, the 431 will act a lot like the original 13 by 14 and was Joe's recommendation based on some of his previous destructive testing

Tim says a 13 by 13 Acme is not enough prop, which would lead to the 1459 choice

So...................which one?

He's gonna use it to pull skiers, cruise around and (don't read this part Pete), pull tubes

I'm gonna be in his area at the end of the week and we'll get the old prop and goofy collar off, check the shaft taper, see if it's straight and depending on our mood maybe even do some lapping

Then the new one can go on and see if his issue is resolved or maybe there's a transmission or coupling issue to deal with

KENO wrote: check the shaft taper, see if it's straight and depending on our mood maybe even do some lapping

If so, make sure you wear your white monogrammed dress shirt.

Chris, you are getting some first rate help!

TRBenj wrote: 1459 minus some cup would be ideal. 1598 in lefty form (same prop but .080). The 431 would run closer to 1:1 at 5100rpm, the boat should be capable of 55 if the motor is healthy.

Thanks for all the help everyone. Would this be the ideal prop you’re describing except 1”?

http://www.nettleprops.com/store/p/440-Acme-1595-Propeller-3-Blade-13-x-14-LH-1-1/8-Bore-080-Cup.aspx

63 Skier wrote: KENO wrote: check the shaft taper, see if it's straight and depending on our mood maybe even do some lapping If so, make sure you wear your white monogrammed dress shirt. Chris, you are getting some first rate help!

Dave

I'm out of lapping compound, So I think I'll mix up some sandblasting grit with some toothpaste and give it a whirl

I'm just not sure if I should use extra whitening or fluoride or maybe some herbal more natural type stuff.

Crest, Colgate, Aim, and so many others to choose from

Decisions, decisions

A new shirt is on the agenda too.

GottaSki wrote: Mav, while we sort this out, whats the list number on the carb's air horn? should be -9022. Let us know is you find something different.

That’s it 9022, it codes out to an 800 cfm

Mav, three decades ago with a similar boat (sister boat to yours) a wise man limited our boat speed with tubes to 22 mph, else it gets put away.
Believe me, you can still cause both fun and carnage with those limitations and i still use that rule of thumb towing our guests (when the lake is clapped out on a weekend, of course)
Your boat is capable of absolutely wrecking someone, so just wanted to pass on don't let your guard down

JoeinNY wrote: TRBenj wrote: 1459 minus some cup would be ideal. 1598 in lefty form (same prop but .080). The 431 would run closer to 1:1 at 5100rpm, the boat should be capable of 55 if the motor is healthy. Based on what boat?   Am I forgetting a 2001 hull boat that has shown a legit 54 mph on a gps? A 431 for the win - 5250 at 53-54 gps mph on a good day would be my bet. My dynoed 403 hp - lighter engined LH version wasn't asking for more prop than a 431. I was down 10 percent cubic inches so likely down a bit of torque lower in the cure and therefore might have enjoyed a bit more prop but I doubt it would be worth lugging the motor all the time. I think the general rule of unless you increased displacement you should keep the same prop but expect to spin it faster applies.    - My 431 met a very large rock at a very slow speed - one blade folded over badly - operator error for sure.   Although I am going to blame the equipment operator that built the brand new pier with ladders and cleats and a pile of boulders all along the side 12 inches under the water.

Ordered a 431 today and the other one was shipped back. I should have the 431 on Friday

Well, after a trip to Mav's this morning, he got the puller and was waiting on the prop to show up later in the day.

The old prop was beat up but not terribly bad, we (or I should say he got the prop off while I helped) without much problem.

Part of my "help" was checking out the rest of the boat, engine, drivetrain etc and letting him know what I found.

Other than finding a big ol' 454 in there, he had replaced the original HEI automotive distributor with a Delco EST( that's for electronic spark timing) Marine distributor.

No flyweights and no springs, the advance curve is programmed into the module.

It was a good looking install

Next I was looking at the transmission coupler and shaft couper and got to break the news to him that he has an ARE shaft in the boat

Moved on to checking the runout on the shaft and it was straight and spun easily by hand even with a dry cutlass bearing. No excess play in the bearing either

Took some pictures that will get posted later

The boat itself, like mentioned in his other thread is an 84 that's had the Rustoleum stripes stripped off and the maroon on the sides is done in something that's as hard as nails and then OEM vinyl lettering put in place.

The interior is kinda rough but that can be taken care of

The pylon is a tall factory one that sticks up above the windshield slightly.

He has the same rudder rash as Flyweed just posted about only not quite as bad. Since it's a Lefty, the rash is on the right side of the rudder

We talked about installing the prop and I m mentioned a few other things also and had to disappear because of other stuff I had going on.

I figured he could handle the prop install and a trial run tomorrow.

Not quite though, he called a few hours later to say that the Acme 431 wouldn't go on the shaft and be able to rotate 360 degrees without hitting the prop guard. The old prop had probably an inch of clearance and I had a 13 by 14 oldie that I brought that also had the same inch or so clearance.

Not the Acme though   Funny thing about the rake on the prop

So he's now into a little reengineering of the prop guard and measuring prop and rudder clearance from the pavement, gravel, grass etc in case he unbolts the guard.

He did say that he doesn't have much clearance from the guard to the ground on a level surface. I think he already has the trailer a little nose down from level when towing to gain a little clearance.

Maybe somebody can post a picture of a mid 80's SN with an Acme on the stock CC trailer for comparison

And the shaft isn't too long since there's probably 5/8 -3/4 inch clearance from the strut with the old prop and I didn't see it with the new prop but I imagine it's about the same.

Sometimes even a straightforward prop change isn't so easy

Once he's past this speed bump, then he'll be able to see if the prop cures his issues or if maybe it's a transmission or coupler issue

A few pictures of Mav's boat

The tall pylon


An aluminum intake with brass water passages. I think that's original on the high output engine and expensive


There's something not quite right about the dashboard


Also took a picture of the PCM tag on the engine, but didn't come out real good

It's a PLN WR L10 or by PCM literature it's a 390 HP Left Hand Rotation 454 with a 1 to 1 Borg Warner transmission. and an 8.6 to 1 compression ratio.