[YenkoYS100]

JoeC> My original brochure is not dated anywhere. I'd guess that it was printed after your spec sheet. Comparing my brochure to my "Yenko Stinger Tech Manual" (dated March 1967), the ratings change once again.
Stages I thru III remain as I posted earlier, in both my brochure and manual.
Stage IV changes. In my brochure it lists a stage IV as 240 hp. and 176 c.i. (illegal for SCCA. 164 c.i. + .040 was legal).
In my tech manual it lists a Stage IV at 230 hp. and goes on to say it's basically a ported and polished Stage III with high CFM carbs. This is the engine that won the DP Nationals in 1966.
The manual lists a Stage V at 250 hp. and says illegal for SCCA because of the larger bore.

Now that we are all confused, I'll quit!! LOL

Rick