CLEARANCE OF ROLLER TAPPETS

[Bill Boudway]

Hi,

What's an acceptable amount for the radial clearance on a roller tappet?

Thanks for your help.

Bill Boudway

[Guest imported_Joe Kieliszek]

Hi,

I would not want any internal rolling/reciprocating clearances to

exceed .005 thousands; also check for "flat spots" and rust

pitting on the rollers..

Thanks,

Joe Kieliszek

[nearchoclatetown]

I've wondered about this for some time, was hoping someone that really knew the answer would respond. I think too,as has been suggested there is no clearance with a roller tappet. I think the tappet must be in constant contact for proper function. I think I even remember my neighbor's SB Corvette, with a roller, that has springs under the heads to keep the lifters in contact with the cam. Have you checked with the cam manufacturer?

[Guest imported_Joe Kieliszek]

Hi again,

This is pretty much a guess on my part (maximum clearance). A

couple years back, I made replacement rollers for the lifters on

my 2 clinder Buick motor out of case hardened shafting (sometimes

called "Thomson shafting"). I bored out the soft center of the

shafting to accept hardened drill guide bushings that I had purchased

from McMaster-Carr. Torrington needle bearings would also work well.

I was also able to recondition my cam lobes by rigging up a pivot

arm and counterbalance for the tool post grinder I use on the lathe.

I still haven't fired up the motor though..

Joe

[Guest Stllrng.]

I would agree that you need to be at around .005" of valve lash with the roller tappets. The only time you would have a zero lash type of a situation would be if you had hydraulic roller lifters. Any solid lifter cam, whether it is a roller style or flat tappet must have clearance. If you were to run with no lash whatsoever, you will have a loss of compression and burned valves. Is this as used on a twin six Packard?

[The Old Guy]

In the older Buicks, they ran .008 clearance. The roller tappet was held to the cam with a apring and the clearance was between the push rod and the rocker arm.

[Guest imported_Joe Kieliszek]

Hi again,

I remember reading in a reprinted volume of the Model T repair manual

that the valve clearance should be set "to the thickness of a

thin dime". Boy, thats pretty exact!

Joe Kieliszek