Question about pushrod length
11-01-2005, 05:03 PM
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Question about pushrod length I've heard two sides now and I need to hear from someone that has experience with AFR 205 heads milled .030 and the proper length of pushrod. I've heard that specifically with AFR's you can run the 7.4 and I've heard that any head milled .030 you need to shorten the pushrods to 7.35 getting a little late in my game to be trying to figure this out but any help would be appreciated
11-01-2005, 05:36 PM
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Generally with milled heads you need a shorter pushrod. Some say you can run a stock length pushrod with milling up to .020, but really you have to worry about valvetrain stability and geometry. Check the Advanced section here for a pushrod length calculator.
That should help you.
That should help you.
11-01-2005, 05:42 PM
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it's never too late in the game to do it right. It can be frustrating to catch up with all the 1sy 2sies, but if you do it right the first time, it will save you big bux in the long run. The third post in the cam guide sticky gets into the valve train geometry
11-02-2005, 01:08 PM
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I have AFR's milled .030" and mounted on Cometic .040" gaskets. I am running Harland Sharp rebuilt stock rockers. With the stock rockers I run the 7.4" pushrods from Thunder Racing and have ~.055"->.065" cold preload. When I was running my Harland Sharp roller rockers my best pushrod length was 7.375". Now I am running Jesel SS series with 7.3" rockers for ~.050"-.060" cold preload BUT my geometry is not optimal. I have to shim the stands up and probably go with 7.4" pr's. I went with the 7.3's because that is what my dial indicator told me to go with and I hadn't checked my valve tip wipe. If I had I would have seen my pushrods were too short.
If you are using a cam with a smaller base circle (any cam with greater than stock lift) you will generally need longer pushrods, if you are using stock length valves. If you are using milled heads you will need shorter pushrods with stock length valves. With stock length valves, higher lift cam, and milled heads with different thickness head gasket you need to measure because of the many different parameters. Usually you can calculate the pushrod length if you know the cam base circle. If you don't know the cam base circle, the best way is to use the valve tip wipe method.
If you are using a cam with a smaller base circle (any cam with greater than stock lift) you will generally need longer pushrods, if you are using stock length valves. If you are using milled heads you will need shorter pushrods with stock length valves. With stock length valves, higher lift cam, and milled heads with different thickness head gasket you need to measure because of the many different parameters. Usually you can calculate the pushrod length if you know the cam base circle. If you don't know the cam base circle, the best way is to use the valve tip wipe method.
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11-03-2005, 11:20 AM
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Originally Posted by ArKay99
I have AFR's milled .030" and mounted on Cometic .040" gaskets. I am running Harland Sharp rebuilt stock rockers. With the stock rockers I run the 7.4" pushrods from Thunder Racing and have ~.055"->.065" cold preload. When I was running my Harland Sharp roller rockers my best pushrod length was 7.375". Now I am running Jesel SS series with 7.3" rockers for ~.050"-.060" cold preload BUT my geometry is not optimal. I have to shim the stands up and probably go with 7.4" pr's. I went with the 7.3's because that is what my dial indicator told me to go with and I hadn't checked my valve tip wipe. If I had I would have seen my pushrods were too short.
If you are using a cam with a smaller base circle (any cam with greater than stock lift) you will generally need longer pushrods, if you are using stock length valves. If you are using milled heads you will need shorter pushrods with stock length valves. With stock length valves, higher lift cam, and milled heads with different thickness head gasket you need to measure because of the many different parameters. Usually you can calculate the pushrod length if you know the cam base circle. If you don't know the cam base circle, the best way is to use the valve tip wipe method.
If you are using a cam with a smaller base circle (any cam with greater than stock lift) you will generally need longer pushrods, if you are using stock length valves. If you are using milled heads you will need shorter pushrods with stock length valves. With stock length valves, higher lift cam, and milled heads with different thickness head gasket you need to measure because of the many different parameters. Usually you can calculate the pushrod length if you know the cam base circle. If you don't know the cam base circle, the best way is to use the valve tip wipe method.
Thanks!! 
