pushrod question
Thread Starter
Safety Car
Joined: Jul 2019
Posts: 3,824
Likes: 1,298
From: nashville TN
pushrod question
question on pushrod measuring. 1. am I doing this properly? cyl 1 exhaust to the top of the lobe lift puts the intake at its lowest point. drop in checker tool a hundred times to get to zero lash. torque to 22 ft lbs. minimal side to side movement zero lash. remove tool and measure.
repeat for exhaust side.
measurements are as follows
cyl 1 intake 7.9450"
cyl 1 exhaust 7.9400"
diff. between the 2 are ..005"
these # are before adding the .035 preload +/- .010
cyl 1 intake with preload 7.980
cyl1 exhaust with preload. 7.975
8.0 for the intake/exhaust pushrod sound correct? is it normal to see a .005 difference between the intake and exhaust?
is it normal to see that much difference between intake and exhaust ?
avg all 16 pushrod measurements to get a total of 127.2265 divide by 16 equals 7.9516. add .035 preload equals 7.9866. theres a .010 +/- which would total 7.9966 will be ordering 8.00 " pushrods unless someone sees an issue with my calculations?
repeat for exhaust side.
measurements are as follows
cyl 1 intake 7.9450"
cyl 1 exhaust 7.9400"
diff. between the 2 are ..005"
these # are before adding the .035 preload +/- .010
cyl 1 intake with preload 7.980
cyl1 exhaust with preload. 7.975
8.0 for the intake/exhaust pushrod sound correct? is it normal to see a .005 difference between the intake and exhaust?
is it normal to see that much difference between intake and exhaust ?
avg all 16 pushrod measurements to get a total of 127.2265 divide by 16 equals 7.9516. add .035 preload equals 7.9866. theres a .010 +/- which would total 7.9966 will be ordering 8.00 " pushrods unless someone sees an issue with my calculations?
Last edited by 9sec; Sep 7, 2025 at 06:34 PM.
Pro
Joined: Apr 2018
Posts: 707
Likes: 89
From: Eastern Pa
I would use a 7.98... yes .005 difference is normal.
When I spoke to the guy at Johnson, he did say that the lifters come pumped-up with oil so you/we can get a proper pushrod measurement... Just DO NOT turn the motor over with the pushrod installed with the rocker arm tightened down, because the oil will leak out and throw off your measurements...
When I spoke to the guy at Johnson, he did say that the lifters come pumped-up with oil so you/we can get a proper pushrod measurement... Just DO NOT turn the motor over with the pushrod installed with the rocker arm tightened down, because the oil will leak out and throw off your measurements...
Last edited by Eli-Z06; Sep 7, 2025 at 08:50 PM.
Thread Starter
Safety Car
Joined: Jul 2019
Posts: 3,824
Likes: 1,298
From: nashville TN
yes johnson link bar lifters.
heres my sheet of all the measurements. unfortunately I dont see any place that has a 7.98 size pushrod. most are either 7.975 or 8.00
Oem pushrod measurement. 7.8495
Cyl 1 Cyl 3 Cyl 5 Cyl 7
Intake
7.9450 7.9625 7.9590 7.9550
Exhaust
7.9400 7.9490 7.9550 7.9545
Cyl 2 Cyl 4 Cyl 6 Cyl 8
Intake
7.9575 7.9545 7.9500 7.9540
Exhaust
7.9525 7.9450 7.9440 7.9490
Intake avg = 63.6375 divided by 8 = 7.9546
Exhaust avg = 63.5890 divided by 8 = 7.9486
Ad .035 preload Intake 7.9896
Exhaust 7.9836
Ad +/- .010 intake 7.9996
Exhaust 7.9936
Avg all 16 pushrods = 127.2265 divided by 16 = 7.9516
+ .035 preload = 7.9866
+/- .010 = 7.9966
Ordering 8.00 for all 16 pushrods
heres my sheet of all the measurements. unfortunately I dont see any place that has a 7.98 size pushrod. most are either 7.975 or 8.00
Oem pushrod measurement. 7.8495
Cyl 1 Cyl 3 Cyl 5 Cyl 7
Intake
7.9450 7.9625 7.9590 7.9550
Exhaust
7.9400 7.9490 7.9550 7.9545
Cyl 2 Cyl 4 Cyl 6 Cyl 8
Intake
7.9575 7.9545 7.9500 7.9540
Exhaust
7.9525 7.9450 7.9440 7.9490
Intake avg = 63.6375 divided by 8 = 7.9546
Exhaust avg = 63.5890 divided by 8 = 7.9486
Ad .035 preload Intake 7.9896
Exhaust 7.9836
Ad +/- .010 intake 7.9996
Exhaust 7.9936
Avg all 16 pushrods = 127.2265 divided by 16 = 7.9516
+ .035 preload = 7.9866
+/- .010 = 7.9966
Ordering 8.00 for all 16 pushrods
Pro
Joined: Apr 2018
Posts: 707
Likes: 89
From: Eastern Pa
Just a heads up, if you order 8.0 pushrods, they Will be longer than 8.0.... The number on the push rod will Always be longer..! I've seen it . 020 longer..! I would order the shorter ones, and remeasure them... I would also use a 3/8 pushrod for some added stiffness... 👍🏻
Thread Starter
Safety Car
Joined: Jul 2019
Posts: 3,824
Likes: 1,298
From: nashville TN
Just a heads up, if you order 8.0 pushrods, they Will be longer than 8.0.... The number on the push rod will Always be longer..! I've seen it . 020 longer..! I would order the shorter ones, and remeasure them... I would also use a 3/8 pushrod for some added stiffness... 👍🏻
after sleeping on this come to a realization im going for the length wrong. went to the max .035 +/- .010 if I go from the actual avg. length of 7.986 and subtract the .010 I get 7.976. so ordering the 7.975 would be perfect and if they do run long I still have a .010 window to play with. THANKS FOR THE INFO!!
Last edited by 9sec; Sep 8, 2025 at 06:56 AM.
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Pro
Joined: Apr 2018
Posts: 707
Likes: 89
From: Eastern Pa
Just a reminder, the bolt that goes into the intake-rocker, you must use a high temp sealant on it.! I would also use assembly lube on the tips of the rockers and push rod ends to help with startup.
Last edited by Eli-Z06; Sep 8, 2025 at 10:18 AM.
Thread Starter
Safety Car
Joined: Jul 2019
Posts: 3,824
Likes: 1,298
From: nashville TN
Drifting
Joined: Jun 2019
Posts: 1,990
Likes: 903
From: near philly
when I built my custom engine the method I thought was right was first just using an adjustable length pushrod, and putting layout fluid on the tip of the valve stem.
Then cycling the lifter looking at the wear pattern to "zero in" on getting the line right on center. Since the rocker sweeps across a path when cycling you just look for centering.
That way it doesn't put a big side load on the guide when it cycles.
As far as I know that's the only way to truly be sure it's precisely the right length and will sweep right on center on the tip of the valve
This method only really works with roller rockers though, so not sure if this car uses that.
Then cycling the lifter looking at the wear pattern to "zero in" on getting the line right on center. Since the rocker sweeps across a path when cycling you just look for centering.
That way it doesn't put a big side load on the guide when it cycles.
As far as I know that's the only way to truly be sure it's precisely the right length and will sweep right on center on the tip of the valve
This method only really works with roller rockers though, so not sure if this car uses that.
Thread Starter
Safety Car
Joined: Jul 2019
Posts: 3,824
Likes: 1,298
From: nashville TN
when I built my custom engine the method I thought was right was first just using an adjustable length pushrod, and putting layout fluid on the tip of the valve stem.
Then cycling the lifter looking at the wear pattern to "zero in" on getting the line right on center. Since the rocker sweeps across a path when cycling you just look for centering.
That way it doesn't put a big side load on the guide when it cycles.
As far as I know that's the only way to truly be sure it's precisely the right length and will sweep right on center on the tip of the valve
This method only really works with roller rockers though, so not sure if this car uses that.
Then cycling the lifter looking at the wear pattern to "zero in" on getting the line right on center. Since the rocker sweeps across a path when cycling you just look for centering.
That way it doesn't put a big side load on the guide when it cycles.
As far as I know that's the only way to truly be sure it's precisely the right length and will sweep right on center on the tip of the valve
This method only really works with roller rockers though, so not sure if this car uses that.