Reply To: cylinder head identification please rd-17

[The red boat]

thanks for the info.
I’ll have to inspect the head when I get home later and see if i can find a part number that matches one of those.

I have an RD-17 that is in good running order but I swapped spark plugs this weekend and stupidly stripped one of the plug holes. The NGK plugs seemed to thread a bit differently than the Champions I removed and i somehow over-tightened the bottom one. The top plug installed perfectly so maybe the NGK plug was at fault? i don’t know but I’ve never had that happen before.

Anyway – I also have a second RD-motor that runs but the compression was not as good so I’ve had it in storage. That’s the one with the red-primer cylinder head.
I removed the head and it looked pristine in the combustion chambers. But since it is not green, it is obviously a replacement from a different motor.

I was just trying to find out what it may have come from because I was going to install it on the better-running motor to replace the stripped head.
just trying to find out as much as i can so I don’t mess up the good motor.

do 25hp heads form different years interchange?