Re: push rod lengths 351c

Posted by john McPherson on September 02, 2005 at 08:25:37 from (216.251.170.201):

In Reply to: push rod lengths 351c posted by c loveridge on September 01, 2005 at 02:25:44:

Pushrods are usually measured from the ball ends.

The length is not crucial in situations where you have adjustable rockers and have to set valve lash, but early on Ford use "positive stop" rocker studs. Clearances are such that there is some "forgiveness" built into the engine.

if the pushrod is too short, the valve does not open fully. If it is too long, depending on the type of cam, Lobe timing, lobe lift, piston type- flat top, Dished (low compression) or domed (high compressions usually 11:1 and 12:1 (not usually found on the road) you run the risk of a valve contacting the piston face.

Valve lash is usually done on a hot engine. And with "positive Stop" types, the ideal lash value will be in a range. If outside of the range, a different length pushrod is used to bring it into the range.

Most valve train noise will be either "play" or wear in the components, or a hydraulic lifter not fully "pumping up". or interference between pivot and rocker arm. Occaisionally you will hear if a pushrod is wearing excessively against a guide plate"(not all engines used them).

Solid lifters will always be noisy from the "play" going to zero as the lobe lifts the lifter.

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