Rocker swipe pattern, hows this look?
Thread Starter
Joined: May 2018
Posts: 360
Likes: 26
From: Opelika Alabama
Rocker swipe pattern, hows this look? 
WHAT DO YOU THINK?
just did trick flow heads "fast as cast" 220's on an 06 LS2 corvette, saw 1000's of vid's on push rod length checking but NONE on how to do it , if you have ADJUSTABLE ROLLER ROCKERS, Soooo... TRICK FLOW says their heads are made for 7.500 PR's ,Deck is 100 thousands thicker. I'm using Crane cams roller rocker arm kit, they give you 7.250 PR's for a stock LS1,6,2,3 kit So that would mean that one would now need a 7.350 push rod, now I have an aftermarket cam that was already installed. So getting the base circle was not an option, But it is not to big of a cam So, I added.025 and went with a 7.375 long push rod and this is the swipe pattern I got after a 500 mile run
That looks pretty wide. If you have the Crane adjustable rockers that converts your rockers to a stud mount style, look up how to check pushrod length and rocker geometry for a SBC. It's pretty much the same, but the torque on the lock may be different.
Thread Starter
Joined: May 2018
Posts: 360
Likes: 26
From: Opelika Alabama
isn't the width of the swipe dependent on lift? how would make it narrower? I thought the geometry was about perfect, I thought my be if you added about .005 it would be dead center, but I'm not going to have custom made PR's made.
I should have asked more about your build before just posting.
When I do wipe patterns, when it is wide and off center to the intake side, it requires more shim under the pedestal. That will narrow it and push it more to the exhaust side. Almost every roller tip I ha e done required 0.100 to 0.120 inches shim under the pedestal to get a nice narrow wipe that was very close to center.
Because your rockers are adjustable, you can shim your rockers up and then move the adjuster to compensate. But only if you have enough thread to work with.
When I do wipe patterns, when it is wide and off center to the intake side, it requires more shim under the pedestal. That will narrow it and push it more to the exhaust side. Almost every roller tip I ha e done required 0.100 to 0.120 inches shim under the pedestal to get a nice narrow wipe that was very close to center.
Because your rockers are adjustable, you can shim your rockers up and then move the adjuster to compensate. But only if you have enough thread to work with.
Thread Starter
Joined: May 2018
Posts: 360
Likes: 26
From: Opelika Alabama
I should have asked more about your build before just posting.
When I do wipe patterns, when it is wide and off center to the intake side, it requires more shim under the pedestal. That will narrow it and push it more to the exhaust side. Almost every roller tip I ha e done required 0.100 to 0.120 inches shim under the pedestal to get a nice narrow wipe that was very close to center.
Because your rockers are adjustable, you can shim your rockers up and then move the adjuster to compensate. But only if you have enough thread to work with.
When I do wipe patterns, when it is wide and off center to the intake side, it requires more shim under the pedestal. That will narrow it and push it more to the exhaust side. Almost every roller tip I ha e done required 0.100 to 0.120 inches shim under the pedestal to get a nice narrow wipe that was very close to center.
Because your rockers are adjustable, you can shim your rockers up and then move the adjuster to compensate. But only if you have enough thread to work with.
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I appreciate you going back and forth with me, I ran back to google to get a better understanding, all these vids with the motor on a stand, SB with the valley wide open makes it a hell of a lot easier then an in car LS, OK if I'm under standing you I need to move the rocker up, on my stud mounted system the only real way I can do that is to increase push rod length, I have already done that by 0.025 I'm running 7.375 PR, you have me wondering if I should be running a 7.400 or a 7.425? The motor runs really strong, BUT it does sound like a sewing machine.
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Originally Posted by KCS
Positioning the rocker too high or too low can increase the width of the sweep. See the image below:
You should be using an adjustable pushrod and checking the wipe with different lengths to see what length gives you the narrowest wipe. The rocker could be too high or too low, you don't know because either could cause excessive sweep.
You should be using an adjustable pushrod and checking the wipe with different lengths to see what length gives you the narrowest wipe. The rocker could be too high or too low, you don't know because either could cause excessive sweep.
Typically, it will get narrow and move slightly to the exhaust side at its narrowest. Then, with continued shimming it gets wider again. When I get it where it is narrowest and mostly centered, I run with that.
Once that is done I get pushrod length based on rocker position and preload. Use the adjustable to find zero lash / dead soft touch, take that length, add preload, there is pushrod length to order. I use calipers to measure vs counting turns. When I order I specify I measured with a caliper.
This is the way I do it. I'll get the rocker on, use adjustable pushrod to get the right preload on the lifter. Really it is best to use a checker spring so you do not compress the lifter instead of moving the valve. Then you set the adjustable to zero lash or preload. Rotate to get seat to seat and back. Pull the rocker, check the pattern. If it is wide and on the intake side, I add shim under the pedestal, adjust pr, redo seat to seat and back.
Typically, it will get narrow and move slightly to the exhaust side at its narrowest. Then, with continued shimming it gets wider again. When I get it where it is narrowest and mostly centered, I run with that.
Once that is done I get pushrod length based on rocker position and preload. Use the adjustable to find zero lash / dead soft touch, take that length, add preload, there is pushrod length to order. I use calipers to measure vs counting turns. When I order I specify I measured with a caliper.
Typically, it will get narrow and move slightly to the exhaust side at its narrowest. Then, with continued shimming it gets wider again. When I get it where it is narrowest and mostly centered, I run with that.
Once that is done I get pushrod length based on rocker position and preload. Use the adjustable to find zero lash / dead soft touch, take that length, add preload, there is pushrod length to order. I use calipers to measure vs counting turns. When I order I specify I measured with a caliper.
I disagree with centering midlift. You will always be intake biased and the higher the lift the worse it will be. If you get it centered, midlift will be past the centerline of the valve. Tightest pattern has least side scrubbing.
Teching In
Joined: Apr 2017
Posts: 42
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From: Western NC
The half lift with rocker arm at a right angle method is best IMO.
Last edited by L78steve; Mar 26, 2019 at 11:53 AM.
Thread Starter
Joined: May 2018
Posts: 360
Likes: 26
From: Opelika Alabama
I do appreciate everybody's comments and suggestions, I do wish that everyone would have completely read what I wrote in the OP, Now you do realize that ALL the 4000 vids and tutorials use an old style small or big block to check push rod length, where you can touch the PR thru the valley of the motor. I have YET to see one vid of anyone doing it on an LS motor and after buying all the crap to do it, I finally gave up because once you put the rocker over the stud and the ADJ. PR how in the hell are supposed to turn it, as it is shrouded me from doing so! That's why I was trying to do it with math. As you see if you read the OP. That being said, ALL of your suggestions have led me to add another .025 to the already added length of 7.375 and I put in a 7.400 PR and the motor HAS NOT been this quite since I put the original roller rocker arm kit on the motor OR since I've changed the cam twice! it is VERY QUITE! I now have several sets of push rods for sale, my loss is your gain.
Staging Lane
Joined: Jul 2017
Posts: 81
Likes: 12
Considering you can only get pushrods in .025" length increments, anyway, you could have simply removed the adjustable pushrod, altered it by .025" and reinstalled.a couple iterations of that would have indicated which increment was best.
Thread Starter
Joined: May 2018
Posts: 360
Likes: 26
From: Opelika Alabama
Glad you finally got it worked out.
Considering you can only get pushrods in .025" length increments, anyway, you could have simply removed the adjustable pushrod, altered it by .025" and reinstalled.a couple iterations of that would have indicated which increment was best.
Considering you can only get pushrods in .025" length increments, anyway, you could have simply removed the adjustable pushrod, altered it by .025" and reinstalled.a couple iterations of that would have indicated which increment was best.
Originally Posted by cmysix
Oh and you can have push rods made in ANY size you want, custom made. love to see the price on that one.