302 water ?

[Lights]

What is working as far as setup for getting plenty of water for you 302 guy's? I would like to run one, but I her the don't pump well.


Thanks,
Mark

[stu_racing]

i had the same question as you earllier this winter and here what i've gathered. the 302's don't like to be kicked in too much, they like a tunnel or relief in the back of the boat. some people have been experimenting with putting the transom in on a steeper angle to move the motor farther away from the boat. you also have to eperiment with you water output hoses to avoid "vapor lock"

[DougMc]

you also have to eperiment with you water output hoses to avoid "vapor lock"

What is "vapor lock"?

[Lights]

I think Spencer meant vacuum lock.

[DougMc]

I think Spencer meant vacuum lock.

I don't know what that is either. I'm mechanically challenged, but learning.

[Lights]

Basically it is water not able to flow because of the configuration of the circuit.

[Lights]

Anyone else got some info besides Spencer????

[Trihedral_1]

Like any new setup, you can start with a conservative engine height (center of the propshaft an inch below the boat bottom for hydro) and work your height and speeds up from there. The 302 doesn't have a pump, and only cools from the props water pressure. Different props can make a big difference once you've got things up to speed...
Just remember: "steam is bad".

[Richard K.C. Mo.]

Prop pressure?

Like any new setup, you can start with a conservative engine height (center of the propshaft an inch below the boat bottom for hydro) and work your height and speeds up from there. The 302 doesn't have a pump, and only cools from the props water pressure. Different props can make a big difference once you've got things up to speed...
Just remember: "steam is bad".

Please explain , is this system like old omc motors , like i mean prop fed?
Thought it was pressure fed from the front.
Richard

[Trihedral_1]

Yamato Motors actually calls it a "Propeller ram water intake".
Overall, cooling the motor isn't really a big problem.

[nightmoves]

Watert is forced into the motor from the prop pushing it up through the tail of the tower, hoses were added to the lower output of the block so to force the water to flow up higher in the block and exit to top water hole of the block evenly with the bottom. Without the hoses the water is more inclined to leave the bottom hole and heat up the top cylinder causing a lean top/rich bottom issue.
The height of the motor for a hydro is recommended not to exceed 3/4 and most guys are running 1 inch below bottom. Hydros have a tunnel thus getting the lower unit higher out of the water in the straights causing a heat problem and in the turns burying the motor again cooling it, there is a happy medium but it is different from boat to boat sometimes.
The more set back the motor is from the bottom of the boat helps in this from creating a greater sign wave of water for the prop to grab and push into the motor, all different kinds of ideas on this but this is the one that makes sense to me.

[Fast Jack]

302

having the lower unit " done" will also help. Tom Cronks work is very nice and the price is right .

[Mike Schmidt]

Props...all props.....

I had the "honor" of having a 302 OSY400 running out of my trailer this year. It has been almost 35 years since I have run gasoline powered anything. What we found out was the higher you can jack them up and still pump water is the key to going fast. The big thing we found out was that some props pump up high, most props don't. Blade shape, diameter, pitch D.M.S., some pump, some don't. We borrowed a LOT of props ( Thanks guys...) Even tried diffrent units and down housings. I am 100% convinced that it is all in the prop. Being able to go up that last 1/4 inch or so is the difference between winning and loosing. It is far easier to prop out a 14,000 RPM Rossi that it is to prop out a 302 Yamato.

Michael D-1