Boat Setup

[foxracing]

Hello, i have just started racing a hydro with a stock yamato 302 in aus. I was wondering if anybody had some tips on the setup. Im getting to 58mph with a 2 blade prop and im after some advice to get that up to what your c class speeds are. heres some pics.

[Fast Jack]

What do your rules allow for props- gear foot shaping - head modifications ? These are some of the best gains you can make in the motor.

[johnsonm50]

What C speeds are varies with condition & course length but is sometimes near 70, My best GPS read was 71 [ I don't beleive it tho..] Usually I get 63 to 66 & am by no means among the faster boats. We set our propshafts at 3/4" deep once the best angle is decided. The race min weight is 440 in C & once running good props are the most important asset, a good one seems hard to come by. 3 bladers are whats used, the 2 might be part of why you're not breaking 60. Good Luck

[ZUL8TR]

[QUOTE=foxracing;n417321]Hello, i have just started racing a hydro with a stock yamato 302 in aus. I was wondering if anybody had some tips on the setup. Im getting to 58mph with a 2 blade prop and im after some advice to get that up to what your c class speeds are. heres some pics.[/QUOTE

Welcome to the world of outboard racing. There are plenty of 302 hydro racers on this site that will provide that info. For a start some info needed to help you:

1. What is the total weight of boat, engine, you, and fuel in running condition, APBA rules use 440 lbs min.
2. What rpm are you presently running the engine
3. What is the depth of the prop shaft end below the bottom , APBA rules in csh is 3/4" min
4. Are you running the prop shaft level with the bottom, or tucked in or out.
5. Do you know the pitch and diameter of the prop and the maker, 3 blades are the preferred choice .
6. What advance setting is the ignition set at, should be 0.200" to 0.250"
7. Is the engine compression up to standards, 125-130 psi
8. What fuel and oil mix are you using
9. What plug number and brand are in the engine
10 Does the engine have the standard gears of 14:15
11 What are you using to measure speed. You have a lot to make up in speed from 58 to around 70 for csh but it is possible.
12 Have you checked the block and crankcase mating (fig 8) and exhaust pipe flush with lower unit housing (fig 9) see manual below.
13 Have you re torqued the bolts on the engine as noted in manual especially cylinder head and power head to lower unit
14 What setting are the reeds

Here is the manual

http://www.yamatoracing.net/y302manual.pdf

Nice looking hydro, who made it

[pops67g]

Most of the things mentioned above are relatively quick and easy to check. The 2-blader really can work against you here. With the engine set at maximum legal height the blades are obviously breaking the surface. The 2 blade prop has only one blade at a time in the water. A 3-blader will have 2 blades in the water at a time so more push. Just for kicks one time I tried a 2-blader on my DSH. The diameter and pitch were almost exactly the same as one of the 3-bladers that I had. The difference in performance was almost shocking. Now a 3 blade prop will not make up for a weak engine but it's really the way you should go.

[Shane_B]

Agree that a three bladed prop will provide the speed increase you are looking for. Here in Region 10 we run a Novice C class with two bladed props and get speeds in the high 50s, low 60s - and with same engine/set-up gets much higher speeds with a three bladed prop. And as mentioned, prop performance varies greatly - we are always in the hunt for that elusive prop that will provide best speeds.

ZUL8TR gave some great check points - would also add carb rich/lean setting... if your plugs are wet, need to make it a little more lean until the electrodes on the plugs are dry and a tan color.

[john527]

"SPEED COSTS MONEY, HOW FAST DO YOU WANT TO GO"

[hoosier]

I hope that's a female in front of you in the red boat giving you some plumbers crack

[Aussie Steve]

Where in AUS ? What size course and are you racing 1 pin turn courses . Welcome to the board !

[foxracing]

thanks for the help everyone, as for the engine it runs great and i plan on keeping it stock. Aussiesteve i race at windsor,deepwater,dargle in nsw which are usually 2 pin turns, ive just got to watch out for the tunnels and monos in the turns. looks like i need to start looking for a 3 blade. can anybody recommend a diameter and pitch to start with.

[Shane_B]

Diameters can range from 6 3/4" to 7 1/4" depending on prop type (round ear, tulip, cleaver, etc.). Pitch is about 13" but don't quote me on that - I don't have a pitch gauge to determine my actual pitches. Lots of prop makers around - Craig DeWald makes some good props - charges $350/prop (he will want to know specifics on what you're running now - engine set up, prop shaft diameter (16mm or 9/16"), current prop diameter/pitch, engine RPMs, top speed, acceleration, etc. to build best prop for you. You can also find a lot of used props on this site - but caveat emptor... they're normally for sell because they aren't performing for current owners (doesn't mean they won't perform for you - one prop may be lousy for one boat but work great on another).

Here's a used 3bladed DeWald that just popped up on HR: https://hydroracer.net/forums/forum/m...-prop-for-sale