Mopar Action On-line – Tech Questions


Tech Question

Michael Mays, Moreno Valley, CA, 1970 Ply Duster 360

My combo is as follows: 1979 casting 360, .040″ overbore, stock stroke, Comp XE268H-10 cam (477/480″ lift 224/230° duration). In the middle of a garage rebuild, I came across a new MP Purple 0.508″ cam and hyd lifter set P4120122. Can I use my stock pushrods and the non-adjustable rockers currently on my engine? Thanks!

Mike-

A definite maybe…

> Gotta check for coil bind
> Gotta check that there’s room for the seals at full lift
> Gotta check the geometry and that the lifters are still “in range”
> Gotta ascertain that your valvesprings can keep the lifters on the lobes

Suggest, as a minimum, a pair of adjustable “checking” pushrods.

You’re also approaching the limits of the stock stamped rocker arms..

Then there’s also the issue of tuning. Depending on exactly which heads you are using, valve sizes, port work, manifolding, etc., this could easily be a mismatched combo — meaning the aggressive cam kills off the low end, and the inability of the ports / manifolds to flow at higher RPM kill horsepower!

Rick

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