Timing information which one to use?

[JTuttle]

Good morning to all, i am new to this forum and wanted to take this opportunity to say hey, and pose my first question. I have a 1984 75 Hp Merc. serial number 6558325. It being a 33 year old motor i have sent off for a lot of maintenance parts i.e carb kits, plug wires,plugs,fuel pump rebuild kit etc. So while i am waiting i bought a Seloc manual to brush up on the timing specs etc. The manual calls for max timing 23 before TDC and just dashes for the primary pick up. On the other hand the airbox cover says 27 BTDC at 5500 rpm with timing pick up of 4 ATDC running. Any clues as to which one is correct ? Thanks in advance.

 

[ondarvr]

I'm fairly confident Mercury knows more about the motor than Seloc.

​The Seloc manuals are known to be a bit sketchy on accurate info, or even including all the info you need to know to get the job done.

​The Merc manual is the best option.

 

[JTuttle]

Thank you for the reply i will seek out a Merc manual, again thank you.

 

[nipperdog]

Just curious, is there a fuel octane number mentioned anywhere on the motor or in the merc. owners manual.

 

[JTuttle]

No, I don't see anything about an octane rating,