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I have 56 Ford with a 1972 429. The 72 heads are junk, so I have gotten some 69 heads and had them rebuilt. I am getting some Comp Cams Magnum Roller Rockers and know I will need guideplates and studs. I am not sure which size pushrods to use 5/16 or 3/8. Did Ford switch sizes during a certain year? Why are some 3/8 and others 5/16? HELP!!!!!
Comp lists 5/16" pushrods for '72 to '78 and 3/8" for '69 to '71. Since they list the same lifter for all years, I would think the difference is in the heads, not the block. So, if the blocks are the same, order 3/8" pushrods.
The first thing I would do though, is to order 1 part# 7703-1 Hi-Tech checking pushrod to check your geometry on each corner of the motor. Then order pushrods that are closest to the length you find by checking.
http://www.compcams.com/technical/Ca...106-07/249.pdf
http://www.compcams.com/technical/Ca...106-07/264.pdf
http://www.compcams.com/technical/Ca...106-07/265.pdf
You can run the 3/8. Just match the guide plate to them and be sure the pushrods are hardened to accept the plates. 8.55" in length is stock dimension.
All Ford production 429s & 460s came with 5/16" pushrods from the factory. There are all kinds of pushrod diameters, lengths and even wall thicknesses available for engine building because these options/choices are dependent on the final engine application(s).Quote:
Originally Posted by Mempho
Whether you need the factory length 8.55" pushrod or not depends on which rocker arms you run. Most all aftermarket rocker arms will require a pushrod length that is different than stock and/or applicable only to that brand roller rocker, in order to establish correct rocker arm geomtery, so if you run the Comp Pro-Magnums as you intend, you will first need to figure out your rocker arm geometry and then order the correct length pushrods.
With roller rockers, you will need to run hardened pushrods with the guideplates, because standard pushrods will be chewed up by the guideplates.
Paul
Thanks all for the response, Man this is a great site!