Okay everybody chime in do you or do you not double the degrees when using a timing light? I went thru the search function today because I have a pulley without any marks and was finding TDC on number one rotor. I kept coming up with posts to double IE 20=40 degrees. My digital timing light is a INNOVA if that makes any difference. Let the advance show correctly!

 

Go to the second gen section, and search for this same subject. A user name "rotaryresurrection" just recently did a write up on how to find TDC without marks on the pulley. When I use my timing light to check/adjust timing on a rotary, I don't double anything. I have two marks, and the one to the right is 5 degrees after TDC and the the second mark is for the trailing plugs which is 20 degrees after TDC. There is no relevance to knowing where TDC is, and no need (that I know of) to double what the timing light says. If worse comes to worse, you can buy a pulley from someone where the marks are visible.

 

Thanks for the response but I have already located TDC on the front rotor and wanted to put to bed this doubling of the degrees because it is a rotary. I am rather baffled that the GURUs did not jump on this post.