[Jay S]

I have a cloyes Billet set in my T/A. It varied just like what Jones described, on my most recent one the further down the scale the more it tended to vary. IRC I used the +6 key and would have liked to go a little further yet but the +8 key moved it 4 more.

The more capable the exhaust is, the better it should respond to less advance, and vice versa. Example would be if this was a round port with open headers, it might like less advance, versus d port with RA manifolds and a full exhaust. I assume this is a d port, and if you picked this cam you have headers. If it is a timing chain engine the torque to rotate the cam adds some slack, generally add 2* from were you have it on the stand turning it by hand. Doesn’t apply if it is a belt drive or gear setup. But at 105 it is really 107, and your difference at tdc is close to .008-.010” less than what your reading. Difference between rolling the engine over on the stand with a bar, versus in to car at 5500 rpm. Advance 2* should change the intake .007”, and only .005 or so on the exhaust, or about 009” total. It will run fine where it is at, but would very likely respond to the extra 2. Tim at Bullet told me in the early days of Ultradyne Brookshire use +6 as there std advance. I would try the 4 and see were it lands, same thing Jones said. FWIW