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-   -   1985 Supra - Prop questions (http://www.wakeworld.com/forum/showthread.php?t=791517)

bigkitch 01-19-2012 6:50 PM

1985 Supra - Prop questions
Hi all,

Gone through alot of new parts on my PCM 351 to try and cure a issue with a hole shot. The boat is a Supra Comp TS6M. Motor purrs like a kitten and runs smoothly through the RPM band.

The problem is the hole shot. very sluggish and is causing the motor to use a lot more power than required. I'm starting to think the prop on the boat isnt stock and was just thrown on to make the sale (judging by the parts I took off!!)\

Anyone had experience with the OJ 3 Blade 13x11.5 (.90 cup) props? When I search, everyone says they are amazing for the hole shot and will keep your top end speed. Boat is primarily used for skiing.

An opinions??

boarditup 01-20-2012 7:32 AM

I think your boat came with a 12" diameter, 12" pitch, 1" shaft prop from the factory. However, please let me know what prop you have on it now and the max rpm at full throttle. I'll shoot you a range of choices. Your boat will not pull like a more modern fuel injected boat, but will have enough hole shot to get up to 36 mph with a slalom skier in tow in 220' or so.

bigkitch 01-20-2012 10:19 AM

You might be right, but I think it was a 13". Here is the photos of the prop.

Could this be a carb issue? I know the boat wont pull like a modern fuel injected, but I would like to increase the hole shot performance.


spencerwm 01-20-2012 12:01 PM

Either the OJ 316 or the Acme 543 would give you what you need. Top end will be high enough to ski and the low end hole shot is awesome. Even at elevation you should get on plane and maintain speed fairly well. You could even go to a 13x13 as well but I personally would try and get the best performance gain. I have been using the 543 on my 1989 ProStar 190 with the 351 and have been completely satisfied.


cadunkle 01-20-2012 3:16 PM

You sure the engine is healthy and in good tune? Fuel injection has nothing to do with how the engine will pull. The engine doesn't care how it gets the fuel/air mix, only that it is right for the conditions. Personally I avoid fuel injection. It's expensive and difficult/time consuming to fix compared to carbs which generally just work.

I don't know for certain, but I wouldn't think in such a small light boat that prop would be that bad. Check your initial timing and that it is advancing fully and smoothly. Initial should be around 8*-14*, more is better if it will do so without detonating. Total timing should be around 38* at 3000 RPM. Ensure the secondaries on your carb are opening and not opening late. If it's an older carb check for blown power valve. Too much fuel with create a rich bog condition. Aside from that, good strong spark, clean cap+rotor, etc. Just make sure it's running right before throwing props at it. What is your WOT MPH and RPM? Should be in the 4400-5000 RPM range as a general ballpark.

andrewjet 02-08-2012 3:53 PM

It is the prop most likely. I ate thru a tank of gas in a half a day of riding because the stock prop was just to low on pitch and surface area. After putting on my 14x14 the boat can enter races now with a good chance of wining!! lol. GO BIG!! ITS WORTH EVERY PENNY!!

boarditup 02-10-2012 7:42 AM

You need about a inch from the prop to the hull so you don't get hull erosion in that area. I could not see from the picture. An Acme 3-blade would increase your surface area by a wide margin, so that would be a dramatic improvement. Looking back, most used the Acme 543 and liked it. I believe you have a 1" bore.
