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Camshaft lifters

Posted By RayCarter18 10 Years Ago
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OlWeldinrig
Posted 9 Years Ago
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 I realize this is an old thread but was thinking about resurfaceing a set of lifters for my 312.
   I thought the lifters were flat and cam lobes were tapered or not "square" to promote the lifter to rotate.I remember from auto mech coarse where an instructor told me to always check a new cam shaft for taper because he has found out of the box jobber cams that were flat causing premature wear.Or is this different on a Yblock?(concave lifter face)We planned on using a very old valve machine which has a flat stone for doing flathead lifters.
Dave 
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Dave.  ...Just to recap what has been previously shared
- the surface of each cam lobe on your cam shaft has a slight taper from the front of the engine toward the rear...
- each valve lifter face that contacts the camshaft lobe has a convex (crowned) surface...
- the valve lifter crowned face makes a line of contact with the slightly tapered cam lobe face it mates with...
- the taper on the cam lobe mating with the convex crown of the vale lifter causes the valve lifter to rotate in its bore as the camshaft rotates to actuate the valve...
- the rotating valve lifter causes the connecting pushrod between the valve lifter and rockerarm to also rotate...

New or properly resurfaced valve lifters have a convex face.  They do not have a flat face.  A valve lifter with a concave face is WORN and will ruin a cam lobe quickly.
New camshaft lobes are slightly tapered from one edge of the cam lobe to the other.

My understanding is that...
- the machined surface finish of the cam lobe and the mating valve lifter face are important
- the machined taper of each cam lobe is important
- the machined convex form of the valve lifter face surface is important

Recommendation
- new camshaft, use new or properly resurfaced valve lifters
- do not resurface used valve lifters yourself;  use someone with the correct equipment and experience for the work
- use of proper assembly lube for lobes and lifters
- use of proper engine oil containing the correct amount of zinc additive for solid type lifters
- follow engine break-in procedure described earlier in thread for new camshaft and new or resurfaced valve lifters

Hope this helps.   Smile 


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OlWeldinrig
Posted 9 Years Ago
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Thanks for clarification
Dave


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