Topic: 390 pushrods

[67gta]

When I replaced pushrods on my 67 S code because of a cracked rocker arm, they were 9.62" in length. I just opened up a friends 68 S code Cougar for a worn out cup rocker arm and the pushrods are 9.56" in length. Stock cams.
Why the two different lengths? Does it matter as long as all are the same length?

Jim

[RoyceP]

One or the other is likely aftermarket replacement. You might need shorter or longer pushrods after an engine rebuild or a valve job. With non - adjustable rocker arms the length of the pushrods is the only way that you have to set proper lifter adjustment. 

When I replaced pushrods on my 67 S code because of a cracked rocker arm, they were 9.62" in length. I just opened up a friends 68 S code Cougar for a worn out cup rocker arm and the pushrods are 9.56" in length. Stock cams.
Why the two different lengths? Does it matter as long as all are the same length?

Jim

[196667Bob]

While an "Aftermarket" part can always carry along with it as not being exactly like the original, I think a more likely difference in this case is a change that was made by Ford. I have attached a page from the 1960-68 Ford Master Parts Catalog that shows Push Rods for 390's. Note that prior to 01/15/68, it shows the Push Rod as Part # C4TZ-6565-B, at 9.62" long, and to be used with Tappet (Lifter) C3DZ-6500-B (a carryover from previous 352's) ; for "from 01.15/68", it shows the Push Rod as Part # C8AZ-6565-A, at 9.59" long, to be used with Tappet C8AZ-6500-A. In addition, to confuse matters further, note that several "oversize" (OS), and "undersize" (US) length push rods were added as new parts (in case you are interested, the circle with the line through it "Indicates changes and additions such as change in model application, dimension, etc." and the "§" symbol "Indicates part number being added").

Just a good possibility of what you have encountered.

Bob

[67gta]

Thanks Royce and Bob for the info. A date is always good to go by. But now how do you find the correct lifter unless NOS. Summit lists lifters from start to end of all FE engines??

[J_Speegle]

................But now how do you find the correct lifter unless NOS. Summit lists lifters from start to end of all FE engines??

Would start by comparing the specifications of the aftermarket ones to the measurements provided in the MPC

Likely the prior page to the one posted section 6500

[196667Bob]

Since you asked ; the C3DZ-6500-B is 1.77" long, and the C8AZ-6500-A is 1.82" long. Apparently, later on, Ford didn't think that this really made any difference as between July of 1968 and July of 1969, the C3DZ is shown as being Replaced By the C8AZ. However, they do note under the tappet that it is to be used with the C8AZ push rod ; and under the push rod that it is to be used with the C8AZ tappet.

Bob

[markb0729]

Always check valve train geometry when replacing any parts on the valve train unless everything is 100% OEM with no milling of block or heads.  I learned this the hard way after a botched engine rebuild by a so called Ford expert.