Roadjunkie1
Well Known Member
A friend of mine recently purchased an RV-4 with an O-320-D1A that, as typical, has 25 degrees on the data plate as the advanced timing. The starter ring has the imprinted 25 degree mark but a drawn Sharpie red mark at about 26 degrees. It is currently timed at 25 degrees and runs well. He is wondering (and I can't answer his question) what the purpose of the red mark at 26 degrees would be. Two Slick mags, one impulse. 5400 foot field elevation. I did not know but told him there are a BUNCH of people who might. Anyone have any experience with advancing the timing to 26? One mag at 25 the other at 26? (Insert Shrug Emoji ....)