Variable lifters?

[razorbac]

I read a posting at one time that made mention of a variable pump-up lifter. Can someone point me towards more info?

[pishta]

Look up Rhoads lifters or Crane Hi-Intensity lifters. Both are "variable duration" type lifters. Basically they bleed down fast to allow you to run a long duration/high lift cam with decent idle and low RPM driveability by never showing the valves the full duration of the cam because the lifters are already collapsing due to the "metering slot" that is manufactured into the lifter body. It is like a big leak. At higher RPM's the "leak" cant bleed off the oil pressure in the lifter fast enough, so the lifter stays pumped up and the valves see the whole cam. This is how it was explained to me and after using the Crane's in my 484 purple chaft 340, I believe it. It idles very nice with great vacuum, and did wake up after 3000 RPM, although it was a little loud under the valve covers. Maybe a band aid for a poor cam selection, but it worked for me.

[razorbac]

I have the same cam in a 340. I'm going to swap the intake/carb back to stock and thought I might try those lifters. I thought it might be cheaper and easier than getting a torque converter to match the cam. I can't seem to make the commitment to change the cam.

[1972roadrunner]

i have rhodes 'variable duration' lifters in my 340, with a .509/292* stick in it, also 1.6 MP roller rockers. the lifters brought a smooth, high vacuum idle to it, and allowed the motor to run 'streetable' untill about 3,000 RPM. then it was like a completely different engine!

i think you'll enjoy them, especially with a big cam.