Pushrod length
Logistics Pro
Joined: Aug 2014
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I wouldn't send it or get longer push rod. There is something wrong with the geometry or the way you are checking the sweep pattern.
I would use a jiffy marker, cover the whole end of the valve, then get an adjustable push rod and check correctly.
The width of the pattern should be less than 1mm.
What heads and rocker arms are you using?
Pedestal mount, adjustable, roller tip, roller rockers?
I would use a jiffy marker, cover the whole end of the valve, then get an adjustable push rod and check correctly.
The width of the pattern should be less than 1mm.
What heads and rocker arms are you using?
Pedestal mount, adjustable, roller tip, roller rockers?
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Cross-Country
Joined: Mar 2015
Posts: 58
Likes: 5
I wouldn't send it or get longer push rod. There is something wrong with the geometry or the way you are checking the sweep pattern.
I would use a jiffy marker, cover the whole end of the valve, then get an adjustable push rod and check correctly.
The width of the pattern should be less than 1mm.
What heads and rocker arms are you using?
Pedestal mount, adjustable, roller tip, roller rockers?
I would use a jiffy marker, cover the whole end of the valve, then get an adjustable push rod and check correctly.
The width of the pattern should be less than 1mm.
What heads and rocker arms are you using?
Pedestal mount, adjustable, roller tip, roller rockers?
Logistics Pro
Joined: Aug 2014
Posts: 3,547
Likes: 845
That’s a pretty wide sweep.
Check your geometry at half lift—the rocker should be 90° to the valve stem at that point. If it’s not, the sweep will be wider than it should be.
Pushrod length mainly shifts the sweep pattern across the valve tip. Longer pushrods move the pattern toward center/exhaust, shorter pushrods move it toward the intake.
On a pedestal setup, shim height affects both the sweep width and where mid-lift occurs.
Based on your pattern (starting intake and moving toward center), the geometry looks too high—you’re likely hitting mid-lift too early. I’d try reducing shim height and/or a slightly shorter pushrod, then recheck the pattern.
Check your geometry at half lift—the rocker should be 90° to the valve stem at that point. If it’s not, the sweep will be wider than it should be.
Pushrod length mainly shifts the sweep pattern across the valve tip. Longer pushrods move the pattern toward center/exhaust, shorter pushrods move it toward the intake.
On a pedestal setup, shim height affects both the sweep width and where mid-lift occurs.
Based on your pattern (starting intake and moving toward center), the geometry looks too high—you’re likely hitting mid-lift too early. I’d try reducing shim height and/or a slightly shorter pushrod, then recheck the pattern.
Last edited by wwhite; Apr 7, 2026 at 09:31 PM.
Logistics Pro
Joined: Aug 2014
Posts: 3,547
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Or, put some scotch tape on the valve stem and sharpie on the tape.
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If you have a bolt down pedestal mount rocker arm the pushrod length should not really change the contact pattern to any great degree. It will change the rocker ratio because it changes the position of the adjuster.
Either way where the contact occurs on the end of the stem makes no difference. The only thing that matters is the pattern of movement. For most rockers the contact point should sweep outward until mid lift where it stops and then starts to sweep back inward toward max lift. If it is inboard or outboard does not matter just as long as it doesn't run off of the edge you're fine.
Either way where the contact occurs on the end of the stem makes no difference. The only thing that matters is the pattern of movement. For most rockers the contact point should sweep outward until mid lift where it stops and then starts to sweep back inward toward max lift. If it is inboard or outboard does not matter just as long as it doesn't run off of the edge you're fine.
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Cross-Country
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If you have a bolt down pedestal mount rocker arm the pushrod length should not really change the contact pattern to any great degree. It will change the rocker ratio because it changes the position of the adjuster.
Either way where the contact occurs on the end of the stem makes no difference. The only thing that matters is the pattern of movement. For most rockers the contact point should sweep outward until mid lift where it stops and then starts to sweep back inward toward max lift. If it is inboard or outboard does not matter just as long as it doesn't run off of the edge you're fine.
Either way where the contact occurs on the end of the stem makes no difference. The only thing that matters is the pattern of movement. For most rockers the contact point should sweep outward until mid lift where it stops and then starts to sweep back inward toward max lift. If it is inboard or outboard does not matter just as long as it doesn't run off of the edge you're fine.
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Why would the sweep pattern change at all if he has a bolt down style rocker arm when changing the length of the pushrod?
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I had the wrong lifter in during the first test and realized I had not torqued the rocker which elevated the trunnion causing the geometry to be off. I put the correct, shimmed lifter in and got the rocker torqued correctly and it fixed the sweep. I will test it on the exhaust valve and confirm. Measure 20 times and cut once.