Props...what to buy?

The best thing I can tell you is to call Delta prop and tell them what you have.They should be able to tell you what you need with what your trying to do.

TRBenj wrote: Or he could tell us what he's trying to do. There are lots of people here with lots of experience with different props on that hull. Matt, are you looking to ski? Cruise? Top speed? Fuel economy? Holeshot?

I want to run 50+ mph like some others said they can. I should have plenty of hp. Worst case, I can ski with my current prop.

JoeinNY wrote: How much horsepower and at what RPM?

Currently it will run 5000-5200 max RPM. The prop I have feels like it has a lot of slip. 351W, 9:1 compression, fully port and polished heads, 1.94/1.60 valves, comp cams 218@.050 - 111 LSA, Performer RPM, 650 carb, MSD 6-AL ignition. Others may disagree but I'd say 300-325 hp.

Brktracer wrote: comp cams 218@.050 - 111 LSA

Whats the lift? Who ported the heads?

I'm not complaining about the cost of one, I'm complaining about the cost of two! I'd like to do it right the first time if possible.

Seriously, I need a prop for my race car too (rear end gears)!

I have family that can help when it comes to engines. My father-in-law is a machinist and has been building stock and race engines for over 30 years (probably closer to 40). He ported the heads and cut them for the bigger valves. Also, milling, screw in studs, 3 angle valve job, and guideplates. His help saved me a lot! Bottom end is balanced and has ARP rod bolts.

The cam lift is .456" This cam is basically PN 35-218-3 ground for reverse rotation. Only exception is the LSA is 111 instead of 110. It has 1.6 roller rockers.

I would have expected a little more RPM than 5000 and I suspect the exhaust manifolds are holding it back a bit. The collector area is relatively small. Also a 750 carb would probably help. But, let's focus on the prop for now.

Thanks,
Matt

Brktracer wrote: The cam lift is .456" This cam is basically PN 35-218-3 ground for reverse rotation. Only exception is the LSA is 111 instead of 110. It has 1.6 roller rockers. I would have expected a little more RPM than 5000 and I suspect the exhaust manifolds are holding it back a bit. The collector area is relatively small. Also a 750 carb would probably help. But, let's focus on the prop for now. Thanks, Matt

Matt, My 351 is very close to what you're running, I'm .030 over, 9.5:1, cam is .460 lift, gt40p heads and a performer. My carb is still a 600cfm Holley. I think you will have a hard time getting it to turn much over 5000 and get any benefit from it and the larger carb will be shot down by many here.

I do agree with Joe about the Acme 540 , it is a great ski prop and you're boat should run tops 48-49 with it. I have an old Oj 13x13 that is my best all around prop and when my boat is tuned correctly and not loaded with peeps it will run 50-51 but the rpms will still not be much higher than 4700-4800. I can turn the Acme 540 which is a 13x12 at 5200 but there's no benefit in doing so.

I absolutely agree with you that the exhaust is a major limitation but the options are expensive. The cost per MPH over 50 is rediculous.

Edit: In case you hadn't noticed the little freindly bantering going on on another thread I'm looking at installing 1.7 ratio roller rockers this spring to help my fairly mildcam selection.    In all due respect to TRBenj, he suggested I didn't go hot enough when I spec'd all my components last year and after only 60 hours on the motor I'm fiddling for a little bit more.

I tryed four props on mine!
1)federl 13x13=4900 rpm at 49.9 mph(not bad for stock prop)
2)acme 540 13x12=4800 rpm at around 48 or 49 mph (did not like it at all)
3)OJ 13x13 three blade 5300 rpm at 53.5 mph(this prop had a few nicks in it, but still worked good
4)oj 13x13 four blade 5200 rpm at 54.2 mph, the four blade was a monster out of the hole and a little better at the top(I liked it the best great power and top speed)

good luck!!

Tim: I agree on the 540. Me and Eddie put mine on a few weeks ago and it would still do 50 per Eddie's new GPS but I had to turn 5600 to get it. To much for my old motor. With the stock Federal 13x14 she would hit 50 at 48 or 4900. I haven't tried my OJ 13x13 Legend (the "nicked-up" prop in MM's post) yet to see how it compares on my boat. MM did like this prop on his boat tho.

john

TRBenj wrote: My prediction is that there will be some seriously fast boats at GL this year. Too bad I wont be one of them

You can be if you switch to an OJ!

Heres somthing to think about, some of the faster boats on this site all run OJs

bill b=74mph(on NOS)
boat dr=58 mph, so he says
Marshall=57.5 mph                  
reidp=56= 56mph and soon to be more
me 54 mph= and soon to be more, I hope
joe ??? whos boat should be up there when he works all the bugs out!

Well the prop can't hurt, but I dont think either tim or I can be in the hunt with our newer boats, I wouldnt rule us out when we get the old boats where we want them. I dont think bill b is running anything near an off the shelf oj, but he definitely was recommending thier products.   I actually really like their xmp line but they dont have anything in the right rotation for the older correct crafts, there is however one on the mustang in my signature and it was a great prop low, top, and in the middle not as big as the acme and a shape more like the legend but very precise and well made. I am going to have to start over tuning my boat this year with a new cam and a new transmission but I hope someday she will be good for 54 mph on the motor, 58 on the bottle.

These boats running in the mid-high 50's...which OJ prop do they run? What is done as far as engine work?

Thanks,

Matt

81nautique wrote: I believe the biggest difference in mine and his is cam and compression ratio as I believe he's running flattops.

Im not sure Mark's boat is a good comparison either- he's got a freakishly fast hull. Mark, correct me if Im wrong, but you were topping out over 50 with the stock cam and heads, correct? If he throws more HP at the thing, I dont doubt he'll be running in the mid-upper 50's.

I was thinking my engine should be good for 5500 and was disappointed it only went 5000. But I know of a couple "issues" that I need to fix. I do know the prop is a problem though as 38-40 mph at 5000 is just wrong!

I do have a vibration between about 24 and 28 or so mph and suspect my prop might be bent slightly causing the vibration at these speeds and also causing cavitation (slip) at higher engine speeds.

I'm far enough south I can play with it this time of year and it's still on the lift so it's just a matter of draining the water when I get back.

I think I'll go ahead and take care of my "issues" and if anyone has a prop they don't mind me trying I'll cover the freight. I'd like to find what works best and I don't mind posting results.

I need to install another distributor or convert mine to magnetic or laser pick up. I'm currently using points to trigger the MSD. This could be limiting my RPM. Also I have a 750 carb to try. I've never tried running on 93 octane and adjusting the timing either. I've only run 87 to this point.

I'm assuming some of you are running the OJ 23102???

Matt

How many hours are on this engine? Are we assuming that the alignment is perfect and the shaft is straight? I'm only saying that it's easier to compare apples to apples...and I've learned miles about alignment and its effects since I've been a member here.

MaddMarxx wrote: 3)OJ 13x13 three blade 5300 rpm at 53.5 mph(this prop had a few nicks in it, but still worked good

Matt: This prop is sitting in my garage doin' nothing if you wanna try it. It is a Legend. MM really liked it on his '80. It was a very good prop on my '80 as well but I have a new 540 that I am in love with (Thanks Mike). Of course I will need it back...don't want to sell it..just want to let you try it out.

john

PS: Hey 79...I think I need some of that stuff you were talking about..still have my points...can I hire you on your next visit? I mean as long as you are suggesting to Matt...well you know I ain't on top of my game under the motor box!