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SORC ballot #3 announcement

Sun, 12/10/2017 - 4:42pm -- Tana Moore

SORC ballot #3 announcement of rules adoption

The enhanced drilling of Yamato engines for cooling has passed by the majority of the commission.

The new rule below will be added to our technical manual with pictures.  There is also a “how to

manual” called the “drilling guide” that is being created and will be available soon in a PowerPoint



Yamato cooling

Proposal: Remove Rule #16, Page 73 of our tech manual and replace with a new rule below:

1) The water inlet hole(s) may be repaired with weld or plastic compounds.

2)  It is permissible to create a groove from the forward side entrance of the original hole location thru the leading edge of the exhaust snout. 

3) The lowest point of the water inlet hole(s) and groove may not be more than 1.400” below the bottom of the cavitation plate.

4) The original contour of the exhaust snout must be maintained.

5) This is permissible on all approved Yamato engines in classes 25ssr, CSR, CSH and 20ssh.

6) See photos on Page 75 of this manual.



1) Sufficient testing has occurred after drilling out the leading edge of the water intake area. It has been found that the motor will now cool sufficiently.

2) With this rule change it will be much easier for our inspectors. They will not have to measure the intake hole, slot or groove size. Only depth location.

3) We will not have our drivers disqualified for the hole that they drilled out themselves and therefore made it too large or too small by thousandths of an inch.

4) Actually, no one has to do this. Each driver can adjust this hole size if needed depending on the specific engine, set up and propeller.

5) In addition to the photos being added on page 75, there will be a "drilling guide" added to the Stock Outboard Resource page on the APBA website.  This will show our members how to accomplish this.

If approved by the SORC, this rule would go into effect 30 days after posting on the APBA website.


Please see your local commissioner if you have any questions or email me at

Thank you,

Jeff Brewster


Stock Outboard Chairman