First time measuring for pushrods, I am confused
Thread Starter
Burning Brakes
Joined: Jan 2012
Posts: 946
Likes: 0
From: Alameda Ca
First time measuring for pushrods, I am confused
ok, so i am confused.
I measured for push rods today. I measured both intake and exhaust on every cylinder, all of them at TDC when i measured. Each side seems to vary by alot.
I measured them to have a .075 preload, and used the adjustable comp cams push rod checker.
Here are my results:
Intake is left side/exhaust right side
#1-7.4/7.4
#2-7.41/7.42
#3-7.33/7.36
#4-7.41/7.41
#5-7.32/7.38
#6-7.41/7.41
#7-7.33/7.37
#8-7.41/7.41
is it normal for the driver side and passanger side to be so far off from each other?
And after looking at this, is there one set length that i can buy that will work for all of them? If so, what am i ordering?
I measured for push rods today. I measured both intake and exhaust on every cylinder, all of them at TDC when i measured. Each side seems to vary by alot.
I measured them to have a .075 preload, and used the adjustable comp cams push rod checker.
Here are my results:
Intake is left side/exhaust right side
#1-7.4/7.4
#2-7.41/7.42
#3-7.33/7.36
#4-7.41/7.41
#5-7.32/7.38
#6-7.41/7.41
#7-7.33/7.37
#8-7.41/7.41
is it normal for the driver side and passanger side to be so far off from each other?
And after looking at this, is there one set length that i can buy that will work for all of them? If so, what am i ordering?
Instructor
Joined: May 2013
Posts: 184
Likes: 4
From: auckland
hi mate not sure what engine you working on ,if you dont have adjustable rockers and your trying to set preload which i presume your doing , couple of things you can do wind your rocker down untill you feel all freeplay dissipear then from there you give it a full turn on the nut give or take a quarter turn if the rocker dosnt tighten at that you need to space it up or muck around and buy a pushrod to suit , obviously if you have valve seat recession on various valves this could take bit of time usually the ex valves that pound out ,the inlets dont give much trouble in that regard ,PM me if you like sometimes its hard to explain on paper good luck
Thread Starter
Burning Brakes
Joined: Jan 2012
Posts: 946
Likes: 0
From: Alameda Ca
It's an LS2. I swapped the whole top end. So now I have:
AFR 230V2 Heads, they have been slighlty milled (but dont know the CC, either 70 or 71)
Brian Tooley Racing lifters
Aruns Stage 3 "Jam Cam""
I used a piston stop, went one way, back the other way, measured to the middle, to be TDC
I am using stock rockers with trunion upgrade.
I was adding preload into the math, not preloading each one as i went.
-I measured off of 0 lash,
-counted each turn on the Comp Cams adjustable pushrod checker as .050
-then added the .075 preload
- then added the 6.8 of the pushrod checker when completely closed.
That is how I came up with these numbers.
Its the variance from 7.32 to 7.42 that worries me, because that seems to me to be very far apart from each other.
Almost the whole driver side was 7.3x and the passenger side was all 7.4x
AFR 230V2 Heads, they have been slighlty milled (but dont know the CC, either 70 or 71)
Brian Tooley Racing lifters
Aruns Stage 3 "Jam Cam""
I used a piston stop, went one way, back the other way, measured to the middle, to be TDC
I am using stock rockers with trunion upgrade.
I was adding preload into the math, not preloading each one as i went.
-I measured off of 0 lash,
-counted each turn on the Comp Cams adjustable pushrod checker as .050
-then added the .075 preload
- then added the 6.8 of the pushrod checker when completely closed.
That is how I came up with these numbers.
Its the variance from 7.32 to 7.42 that worries me, because that seems to me to be very far apart from each other.
Almost the whole driver side was 7.3x and the passenger side was all 7.4x
Melting Slicks
Joined: Nov 2009
Posts: 2,536
Likes: 15
There are several ways to achieve this.....here is one of the more weekend warrior methods.
make sure your on the base circle
using a know length pushrod tighten to zero lash (rocker becomes stable)
Take your torque wrench that is set to 22lb-ft and torque the 8mm bolt
Count the number of turns it takes to acheive 22lb-ft....1 full turn is worth .047"
Adjust the pushrod length accordingly for the desired preload
.
make sure your on the base circle
using a know length pushrod tighten to zero lash (rocker becomes stable)
Take your torque wrench that is set to 22lb-ft and torque the 8mm bolt
Count the number of turns it takes to acheive 22lb-ft....1 full turn is worth .047"
Adjust the pushrod length accordingly for the desired preload
.
Thread Starter
Burning Brakes
Joined: Jan 2012
Posts: 946
Likes: 0
From: Alameda Ca
Yea i did a ton of reading before i did this. The way i chose to do it, seemed less likely to have an error.
My question was about my results though, wasnt looking for another method.
thanks
My question was about my results though, wasnt looking for another method.
thanks
Pro
Joined: Oct 2004
Posts: 510
Likes: 5
From: Pipe Creek TX
If you are totally confident your measuring is correct ; the .100 length differance has got to be in head deck thickness or rocker stud base height. What else can change the length? A test would be to shim the short side studs and see if the length comes out equal.
Last edited by SG4206; Jun 30, 2013 at 01:33 PM. Reason: additioal info
Melting Slicks
Joined: Nov 2009
Posts: 2,536
Likes: 15
Not sure how your numbering them in your post (firing order/actual cylinder numbers or just counting down the banks). But I readlly feel your over thinkin this, measure # 1 & 2 (opposing banks) take the average and go with that. The preload will take the "error" out of the average.
The difference your seeing is in your measuring method. Again, preload is your friend, you want to set your preload in a "safe" zone. Meaning, if there is a little discrepancy from cylinder to cylinder length, let the preload takes care of this. Example; 0.100" of lifter travel shoot for 0.050" of preload, that way if there is a little variance in length its no big deal.
The difference your seeing is in your measuring method. Again, preload is your friend, you want to set your preload in a "safe" zone. Meaning, if there is a little discrepancy from cylinder to cylinder length, let the preload takes care of this. Example; 0.100" of lifter travel shoot for 0.050" of preload, that way if there is a little variance in length its no big deal.
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Thread Starter
Burning Brakes
Joined: Jan 2012
Posts: 946
Likes: 0
From: Alameda Ca
Yes the numbers are per cylinder, drivers side 1 3 5 7, passenger side 2 4 6 8
I agree maybe i am over thinking because ive never done it before, took me a week to even get the courage to even try to measure, lol
I am going to try again, and this time factor in preload in the middle, not on the high end.
I think i may know a few spots that i messed up on. Going to start from scratch today.
I agree maybe i am over thinking because ive never done it before, took me a week to even get the courage to even try to measure, lol
I am going to try again, and this time factor in preload in the middle, not on the high end.
I think i may know a few spots that i messed up on. Going to start from scratch today.
Melting Slicks
Joined: Nov 2009
Posts: 2,536
Likes: 15
To double check yourself.......put you adjustable pushrod in but shorten it so you know it will not contact the rocker, then torque the rocker arm down to 22lb-ft. Now begin to lengthen your pushrod till it is snug against the rocker(snug = can not spin the pushrod because its seated against the lift and rocker). Now loosen the rocker and remove the pushrod. Measure the pushrod and add your desired preload to the measurement. This method works because of the spring in the lifter keeps the plunger "pumped up" when the engine is not running.
.
.
Le Mans Master
Joined: Aug 2007
Posts: 6,473
Likes: 297
From: Orange Park FL
To double check yourself.......put you adjustable pushrod in but shorten it so you know it will not contact the rocker, then torque the rocker arm down to 22lb-ft. Now begin to lengthen your pushrod till it is snug against the rocker(snug = can not spin the pushrod because its seated against the lift and rocker). Now loosen the rocker and remove the pushrod. Measure the pushrod and add your desired preload to the measurement. This method works because of the spring in the lifter keeps the plunger "pumped up" when the engine is not running.
.
.
Drifting
Joined: Oct 2005
Posts: 1,257
Likes: 4
From: North Carolina
To double check yourself.......put you adjustable pushrod in but shorten it so you know it will not contact the rocker, then torque the rocker arm down to 22lb-ft. Now begin to lengthen your pushrod till it is snug against the rocker(snug = can not spin the pushrod because its seated against the lift and rocker). Now loosen the rocker and remove the pushrod. Measure the pushrod and add your desired preload to the measurement. This method works because of the spring in the lifter keeps the plunger "pumped up" when the engine is not running.
.
.
DG