Radiused lifter vs. Flat Lifter

19Fordy

19Fordy

Well-known member
Aside from ease of adjustment, I am curious to know the advantages or disadvantages of installing Johnson adjustable radiused lifters and Johnson flat adjustable lifters in a stock or "built" 49-53 8BA engine. When is one used in preference to the other? Thank you, JIM
 
All Johnson adjustables have, or are supposed to have, a slight radius to them. When held flat to flat, there should be a slight perceptible crown to them. They should not be perfectly flat. When adding a new cam, they need be resurfaced if flat or concave. The purpose is so the lifter will turn when lifted, equalizing wear on the contact surface. Performance issues are not relevant.
 
Russ/40 said:
All Johnson adjustables have, or are supposed to have, a slight radius to them. When held flat to flat, there should be a slight perceptible crown to them. They should not be perfectly flat. When adding a new cam, they need be resurfaced if flat or concave. The purpose is so the lifter will turn when lifted, equalizing wear on the contact surface. Performance issues are not relevant.
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Russ is Correct, the bottom radius is called a 96" radius, the top adj screw is 36" radius. if you hold a razor blade on edge on the bottom you can see it.
 
they also make a radiused lifter for spacific cams like the famous isky 404a and others that are keyed into the bore to keep them for rotating....i think they were before they had roller lifters, the isky 404a cam has like a 1/4 inch flat spot on the top of the lobe,im assuming thats why they need the special lifter,that and the rate of lift? I have a nos cam and lifter set with the waterslide decal and the brass tag..........cant wait to use them
 
I believe the cam lobes are on a slight angle from the center line of the cam, also to promote lifter rotation, to help reduce wear.
 
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