plug selection

blgrams

Seaman Apprentice
Joined
Jul 7, 2004
Messages
48
I just rebuilt a 40hp 1991 johnson. my dealer gave me Ql78YC (gapped to .030) but the book says Ql78C (gapped to .030) . what is the difference? is this a problem? Is there any change that must be made in the carburetion when both cylinders have been bored out by .030
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: plug selection

Ql78YC is the correct plug for your motor. The "Y" plug has a slightly longer nose, but it is the right one. Should not have to worry about the carbs..
 

blgrams

Seaman Apprentice
Joined
Jul 7, 2004
Messages
48
Re: plug selection

thanks,I read somewhere that one of the orifices needed to be changed if the cylinder is bored out.<br /><br />Bruce
 
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