yamato 302 cooling

[apache88]

I understand the cooling system gets water from the rotation of the prop through that small hole at the base of the down tube. I have two questions: Can you improve cooling by enlarging the hole? What is the best way to run the motor out of water. Is there a speical hose adapter for this purpose?

[blueskyracer]

You cannot enlarge the hole and to run it out of water at home you can make an adapter to fit in the hole and hook it up to an electric bilge pump and stick it in a large water source.

At a race there are rules that govern when you can run a boat out of water for safety reasons

[form-e one]

conntact rpm marine,,, ricky will tell ya how to do it right since he the importer,,, his contact info at front of this web site if ya hit portal,,,

[B Walker]

The motor does not care what direction the water runs through it. I made an adaptor to connect my garden hose to the exit passage at the top of the port cover.

Works great

Do not connect to the bottom one on the port cover as you will not flood the head completely.


BW

[ricochet112]

You can back the boat in the water until the cavitation plate is just even with the surface and it should pump, usually at higher RPM's (above idle). Most racers just run the motor for 15-30 seconds (you could probably run it for 1-1.5 minutes before it would over heat) with the prop off to warm it up before backing it in, keep a hand on the top cylinder to check temp. I liked to run my in the water, after I dry fired it, to make sure it was warm and so it would always start on the first pull. After you make a test run (laps) feel the cylinder but be careful not to burn yourself, they will be very warm, to get an idea on how a just run engines temp feels.

PS-to start out with keep it deep to avoid overheating, AND get a temp gauge so you don't burn it up racing, they usually only score the top cylinder if you do stick it.

[seanp3]

You might check with Tom Johnston. He taps a threaded hole in the back of the tower so you can make an adaptor to hook up to your hose so water is going through the block constantly. It works great and keeps it very cool. 517-519-9120

[hydroid]

Out of lake cooling alternatives

You might check with Tom Johnston. He taps a threaded hole in the back of the tower so you can make an adaptor to hook up to your hose so water is going through the block constantly. It works great and keeps it very cool. 517-519-9120

Sean, isn't there one more step w this process? Shouldn't the water inlet hole behind propshaft be duct taped off to prevent loss of water through this hole? If not sealed, wouldn't there be risk top cylinder may be starved of cooling water?

I like BW's reverse flow suggestion. Brad, I understand not feeding cooling water through lower exit passage only, as top cylinder could be starved.
To ensure adequate cooling water volume going through via upper and lower exit passages, one could attach a Y adapter on the end of garden hose, then reduce the 2 hoses from Y to fit the outside diameter(approx 5/8") of the exit passages, use hose clamp to secure. Any reason this wouldn't work? Does the reverse flow process run risk of an air pocket at top of port cover?....not sure here

[seanp3]

Sean, isn't there one more step w this process? Shouldn't the water inlet hole behind propshaft be duct taped off to prevent loss of water through this hole? If not sealed, wouldn't there be risk top cylinder may be starved of cooling water?

I like BW's reverse flow suggestion. Brad, I understand not feeding cooling water through lower exit passage only, as top cylinder could be starved.
To ensure adequate cooling water volume going through via upper and lower exit passages, one could attach a Y adapter on the end of garden hose, then reduce the 2 hoses from Y to fit the outside diameter(approx 5/8") of the exit passages, use hose clamp to secure. Any reason this wouldn't work? Does the reverse flow process run risk of an air pocket at top of port cover?....not sure here

I run my cooling tubes up over the top of the power head. If I get water coming out the cooling tubes I can be sure I have plenty of water in the head for even cooling. Yes you will get water coming out the inlet hole behing the propshaft. But I haven't experienced a problem so long as I have cooling coming out the cooling tubes. I have ran my 302 over an hour this way for break-in purposes at low RPM's.

[B Walker]

If you loop the lower port cover water outflow hose over the top of the port cover you insure full flooding and cooling of the head. Even with water going into the top only. y adaptor would work too.

On another note......1 hr to break in a Yamato??????? One of my motors is so sloppy I would have to re-ring it after an hour of Byrne style break in time.

BW

[Islandmon]

You might check with Tom Johnston. He taps a threaded hole in the back of the tower so you can make an adaptor to hook up to your hose so water is going through the block constantly. It works great and keeps it very cool. 517-519-9120

What Sean refers to is a good solution, I have one as well.