429 pushrod length?

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Jun 23, 2005 | 10:50 AM

8man

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429 pushrod length?

I have a 70 with dove-c heads. I am trying to finish my build. Ordered pushrods from summit for this motor, and they aren't long enough. 8.550 is what they sent, too loose. My repair manual (old) with specs says, run the rocker nut down and then torque 18-22 lbs. I have non-adjustable rockers.
I have read a lot of posts here saying 8.680 is the right length. Is this correct?
How much should the lifter compress (preload) when the pushrods are the right length? Pushrods I bought were $30.00, longer is $100.00 or more. ( all I can find ) Need help.

Jun 23, 2005 | 12:36 PM

monsterbaby

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From: iowa

best bet with none adjustable rockers is definatly get a adjustable pushrod length checker (try you local machine shop) and measure them then you will get the right length for sure not just what the book says cause machining, and valve installed heights, plus the base circle of the cam can all make a difference in the length.

Jun 23, 2005 | 12:56 PM

8man

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But how much preload is right?

Jun 23, 2005 | 01:08 PM

monsterbaby

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From: iowa

well I can't find it in my Ford book but comp, and crane say .030 preload +/- .010

Jun 24, 2005 | 03:21 PM

8man

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Just to let everyone here know. Comp cams says install pushrod ( the one that is too short ) and measure the distance from the rocker tip to the valve stem.
Add .030 to that, and that is the length that you need. They also say that anything between .020 and .060 is acceptable. I am shooting for .030-.040.
Thanks for the help!