New ACME 540

Well, after going thru 3 old props including the one that came with my '68, I installed a brand new shiney ACME 540, 13x12x1 with .080" cup.

The first thing you notice when you pull the 540 out of the box is how large and thin the blades are. The surface area of this prop compared to my older props, is huge! There are also marks in the form of ripples left over from the machining process that cover the entire prop. I have never seen any other props like this one.

The prop it replaced is a 25 year old prop which I pulled off my '66 to replace the 2nd of two props I broke running into sand bars in the bay. (I like to say to the kiddies that read this "don't do this at home" - these little boats are not suited for conditions found in shallow salt water bays.)

The 25 year old prop I just pulled off was a 12x12 with what looked like no or very little cup.

Here's what I found.

First of all when I installed the ACME prop I discovered that it is too large in diameter. The installed clearance between the prop and the hull is about 1/4" but worse than that the clearance between the prop and the prop guard on the trailer is LESS than 1/8" - close to 3/32".

I emailed ACME asking where I should ship the prop to have it trimmed. Bill Weeks at ACME replied very quickly with a shipping address. His email advised me the charge will be $40. He recommeded I run the boat with the prop before I send it in. I guess this is so we have a baseline from where we began with the new prop - so I did.

With the old prop the 289 powered '68 Mustang would almost jump out of the water when I went to WOT from a stand-still. Anyone who rode in the boat always commented with something like "wow"! (It's always fun to wow your friends.) I honestly think it would have beaten my old '70, 340 tricked out Cuda off the line (and it was pretty strong). The boat would run right up to 40 MPH (confirmed with a GPS) at 5300RPMs.

With the new prop the engine and trans definatly have to work harder. The hole shot is not as quite as strong and the engine has to labor to get to 4200RPMs. The trans also makes noises (which I descibe as groaning) which I have never heard before. Interestingly, the boat gets on plain quicker and at a slower speed with the new prop. The boat also rides with the bow lower in the water which is very nice.

Top speed is now 42MPH at 4300RPMs (2 MPH faster and 1000RPMs lower than with my old prop). It takes a long time to get from 4000 to 4300RPMs. The boat actually ran about 50MPH at 5500RPM two props ago but the speed was measured with my "on-the-floor" uncalibrated speedo before I had a GPS so I would not trust the measured speed as being right (but it did seem to be faster).

I was hoping that by some magic, the boat would run with less vibration with the new prop but I still have a little vibration in my drive train which has been present ever since I brought the boat home and even after I replaced the prop shaft and strut bearing.

Summing up, the boat runs 2 MPH faster, seems to have slightly lower acceleration (based on feel and sensation only), gets on plain quicker and rides with the bow lower in the water.

One other thing, I can hear my secondaries open a lot sooner than before - somewhere around 3000RPMs. The secondaries always open when I hit WOT but now at cruising they begin to open at about 3000RPMs. My judgement of this is based purely on sound. (I do a have project in the que to install a prox sensor on the carb to give me an indication of exactly when the secondaries begin the crack open. It is a very low priority project though.)

So, now I will pull the boat out of the water sometime this week, pull the prop and ship it off.

I spoke with Bill Weeks at ACME to get a prop recommendation before I bought the prop and he seemed very knowledgable and is very helpful. He returns calls very quickly and replies to emails almost instantly which is very refreshing. I'm sure based on the above info he will have a knowledgeable opinion on how the prop should be trimmed. I will post those results when I get the prop back from the shop. (Bill said the turn around time will be 2 to 3 weeks.)

One final thing, reports I have read about the boat stopping quicker as a result of the larger blade area are accurate. In fact my trans really groans when I pull the speed down too quickly with the 540 prop. Slow-down is so quick it is uncomfortable and I quickly learned to pull the throttle down much slower than before just to keep from being thrown from my seat.

A final, final note: with the new 540, idling at 600RPMs pushes the boat up to a speed where a small wake is now produced. This will not make my neighbors happy.

The jury is still out but right now I am not overly excited about the prop. It may be just the incorrect size for the boat - I dunno. The prop definatly needs a trim. In fact, if I did not think trimming may help I would probably just go back to my old prop. We'll see.

I was hoping to get out of the house early this morning but this is another thread I've had some recent experience with and can't pass on. Last spring I borrowed a 540 from the local CC dealer to try on my 69 Mustang (modified 302). It, just like JIH, was too close to the hull and it vibrated and resonated all thru the boat as a result. While doing so the boat actually ran slightly SLOWER (1-2 mph)than my current favorite OJ prop, and turned a near identical rpm. So I spoke to Bill Weeks, a great, attentive guy like Jim says, and bought a new one cut about an inch less in diameter. Nope, way too many rpm for this engine and even less speed, but it runs great on Marshall Morgan's 273 Mopar Mustang where it now resides, and is very smooth. Jim, if you like, and when I get back from FLA, I'll box up a 12x13 OJ and let you try that.     

reidp, your advice has been right all the way around. So I will begin looking for a good price on an OJ.

I think the ACME is probably a great prop, it's just a matter of making a good match with a boat and engine.

I would like to try the OJ but I would just as soon buy one as put you to the trouble Reid. (Thank you very much though.)

If anyone would like to have a new ACME 540 for $315.85 plus shipping, (or trade for an OJ like Reid's) let me know and I will send you one. Email me at jim@electricaltrainingusa.com and I will tell you where to send your check. I will also take your credit card.(I will send the customary contribution to Keith.)

I will then buy an OJ prop like Reid's and review it here as well.

If no one is interested I will send to prop to have it trimmed and give it another try.

Has anybody gone through the prop upgrade experience with a 74, 75, or 76 Mustang 17? How'd that work out? Sorry Jim if I'm hijacking your thread...

well jih i live in kemah and if you change your mind let me know. if you do buy 542 i have been thinking about buying anther for a back up. you are also welcome to try the one that came off my boat. i think its a federal 13x13 or michigan wheel something like that.

Joe, it might be the extra clearance of your 13" prop is the result of a lot of rake towards the rear. Just speculating. The prop that pushed my boat the fastest (I think) was an OJ. It had a lot of rake towards the rear. It almost looked more like a screw than a prop.

I broke a blade off of it and bent my prop shaft at the same time. My boat developed a terrible vibration when this happened.

Never been to Outriggers. Yeh, I saw those guys. I have been in a lot worse fixes than that and never called the Coast Guard. That was dumb. They had to be 3 sheets to the wind.

    JIH, I have a 540 I bought several years ago and found it the smoothest prop I have ever had on both boats. I also sent it back several times to Bill to get it trimmed and cup removed, because The hole shot wasnt as good and top end was great. I then put it on my 310 hp in the 76 and found it still didnt do what I would expect on take-off, but was better than the 74. What I noticed most on the positve side is that the prop was the smoothest I have ever seen, and stops quick. The biggest downside of it for me is that found the steering VERY difficult when moving slowly. I couldnt whip it in the dock like I used to. Alot of the difference is probably because it has no tracking fins to keep it put. I also noticed at 30mph or so, the wheel turned very hard to get it to turn, unlike the old OJ or Michigan that I could drive with one finger.
    I currently have a OJ 3 blade (unknown model) that I bought from my local marina about 10 years ago. Its a 12X15, it goes good and is smoother than the Michigan 12X15. I think the Acme has too much blade for the older boats or something. I would like to try a 4 blade some day.
    I still have the Acme in the box, been sitting for a while. I can give you guys what the exact specs are on it if anyone is interested on what was done to it for comparison.
    I did notice the Michigan doesnt nearly have enough blade area to prevent tons of slippage when pulling several people out of the hole.

    Well Jim, I dont think its a bad story. I think maybe our boats are too dam old!!
    I guess our boats dont like too much blade. I am glad to see that Im not the only one that have experienced that. Bill Weeks is one great guy with great service like you mentioned. I wonder if they have a 4 blade or something that might be a happy medium??? Im not real familiar with props except for the ones that I have tried.
                             Jeff...

    Hey Jim, Wheres Jbear to help make you and the boat not feel so old!!!???? I am a believer that sometimes old is better than new...Sometimes too much sophistication can leave you DEAD on the road (or in the water).

   I will also pull out my receipts tomorrow (at the shop) for the Acme prop I have and I think It was $40.00 to grind it a couple of yrs ago.

                             Jeff....

JIH...IMHO An Acme 540 or 542 is 1000% better than the Federal 12 * 14.... That said, I believe most posts advocating the 540/542 are with a few 302's and more 351's. Maybe some guy's will let us know.

FYI right or wrong here's what I did. I liked my old 64 289 so I rebuilt/modified her and placed her in a '72 (heavier boat) with a Federal 12 * 14. Ran OK but nothing to write home about. Like you, I thought it ran better with the old prop/hull...even with the tired engine. Removed the soaked foam and added the Acme 542 and it was great. At 3000 rpm the bow noses down giving the boat great tracking and runs easily up to 4500 rpm. No steering problems. Also cured the porpoising.

The reason I went to the 542 was because I alway's suspected the 289 being a little small for any larger pitch. To tell you the truth, I wish the prop was an 11 or 10.5.

Yeh 64, I think the 540 is just too much prop for my boat - that's the bottom line. A think a 12 x 12 works well - I think I just need to find a new 12 x 12 with the right amount of cup.

Do they make a 12 x 12 with a double D cup? I kinda like those.

I put the new 542 prop on and the boat quit porpoising. SS201 told me the pitch can make the boat run different in the water whcih is what cured the porpoise. After the prop job I removed the foam and performance just got better....but now I need fat sac's for wakeboarding.

I read Keith's article again and his test was with a 4V 302. That's about 70 more HP than an old 289.

JIH, you can make that 289 push that prop using pump gas.

The real beauty of the old Correct Crafts is that Double D's dig Double C's...now matter how they run!

Now that we're talkin' double D's and double C's we got a post I can understand as opposed to all that electrical stuff last week.

J_I_H; I think I've got a radio in the '80 but not sure what its for. Can't hear it with the motor running. And I thought tubes were for pulling kids on.

john

I concur, shaft alignment is very critical.
My particular boat is super smooth because I can adjust the engine precicely within an 1/8-turn on any of the mounts; but that is only possible because it has a double-taper shaft. That precision is rarely repeateble on single-taper hardware because the setscrews skew the coupling - evidenced by rotating the shaft 180 degrees and the alignment goes 'off' again'. One can chase it to no end.

Jim also mentions previously bending parts but I forget if he replaced the shaft. If you do, go double-taper.

Also lap the prop to the shaft, as well as mark the shaft where the prop seats without a keyway to verify that when you add the keystock, it doesn't bind and prevent a good seat, skewing the prop.