Just realized I might've done a stupid thing...

You could also try a set of Rhoades variable duration lifters. They bleed down at idle and take out approximately .025" of lift and 15° of duration. They "pump up" by 3500 RPM and give full lift and duration of the cam.

they will increase idle vacuum. smoother idle, better low end and mid range torque and horsepower. I've been using them for over 25 years without any problems.

You will need part # 1068 for the hydraulic roller lifter for your engine.

I installed them on a 284/484 MP cam that would idle choppy at 1100 rpm with 8" vacuum, after installing the rhoades lifters, I was idling much smoother at 800 rpm and 11" vacuum.

rhoades main page:

http://www.rhoadslifters.com/


Part numbers:

http://www.rhoadslifters.com/Pages/PartNumber.html


Read the second article on how they work.

http://www.rhoadslifters.com/Pages/Articles.html