Vikki, thanks. I went by NAPA and checked out the #29281, it has an "A" stamped on it. I'll get a #118 tommorrow, and I'm betting it has a different letter, possible an "F". I cut my old one (with an "A" stamp) apart today to see what makes it work, and it appears that the difference in parts is in the plunger diameter, and I'm assuming the spring rate, although I didn't cut the other one apart to verify this.
The #29213 / #118 is for the 350s, and lower HP 400s. I'm hoping it solves my problems.
Am I right in assuming that at Idle, the Vacuum from the port below the carb pulls the plunger up against the spring and helps to lower the crank case pressure, then at part-throttle as the Manifold Vac increases, it pulls the plunger further, allowing for more crank case pressure to be pulled back into the manifold. At WOT, the plunger should be at its lowest point (pulling least against the spring) since vacuum is near zero?
