56-59 engines use a different length push rod but I have never figured out why, is it just because of the different rocker ratio?

It's not due to the rocker ratio.  I used 1960 heads with high ratio rockers and '56 - '59 pushrods by mistake.  They were barely long enough and that is probably only because the heads and block had been milled.

I don't know the reason, though.


Lawrenceville, GA

Charlie, you are saying the difference is due to the head casting height dimensions are different on 56-59's?

Edit: sorry I didn't see were you mention you didn't know the reason why..

I've wondered if the shorter push rods were on the cars with drip tins under the rocker stands. They are similar in thickness to the amount of short on the rush rods. Chuck

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Manchester, New Hampshire

I'm a little annel when it comes to pushrod lengths and rocker arm geometry. I always correct what the factory said was adequate whether it was adding shims under the pedestals or milling them shorter. My push rod length is determine after the rockers are in the correct position.
When it's correct there is a lot less sideways push to the valve and the valve guide.

I cut a section out of one and thread each end, use an external coupling for solid ones and all thread for hollow ones. I adjust the length for what I want and sent the sample to Smith Push rods in Oregon or Manton in Arizona. Both are very prompt at least for me. Good luck.


56 Vic, B'Ville 200 MPH Club Member, So Cal.

Maybe that is the difference! Engines with the drip pans would need a longer push rod and without would use a shorter one..

Thanks, I don't have a push rod problem, this is just something that I have always been curious about and trying to find an answer..

Can't be the drip pans since they weren't used on the later engines.



Lawrenceville, GA

Very true Charlie and thats why I find this so confusing and have never seen a definite answer. But didn't the later engines also have the lower rocker ratio?

The longer pushrods on 60-64 heads is caused by the valves being raised in the head. It isn't obvious until you set a C1TE or equal later head next to an ECZ-G and sight the rocker stand height compared to the valve cover rail.

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