Another pushrod length question...
Another pushrod length question... So, I am attempting to check for proper length using the "zero lash -> # of turns to 22ft*lbs" method. The car: 98 z28, stock 806 heads, tsp 228R, LS7 lifters, felpro gasket PN 9284PT, stock rockers. I am using a TSP 7.4in pushrod for the check. I have cylinder at TDC, so definitely on base circle.
I used the method and came up with ~1/8-1/4 turn to 22ft*lbs, which seems way off and I'm fairly certain I was doing something wrong since I believe 7.4 is close to what I need (not an expert on that feel free to correct).
This is exactly what I did:
Got the head on torqued to spec (other head still off car); took 7.4 pushrod and set it in place; installed rocker arm on rocker guide (along with another rocker just finger snug to keep the guide from moving much); tightening the rocker until it would not wiggle horizontally or vertically or actuate freely; took torque wrench and went to 22ft*lbs, took roughly 70deg;
.
Does the lifters being BRAND NEW and I'm assuming not pumped up with oil affect anything? If so, how can I measure with new lifters?
I used the method and came up with ~1/8-1/4 turn to 22ft*lbs, which seems way off and I'm fairly certain I was doing something wrong since I believe 7.4 is close to what I need (not an expert on that feel free to correct).
This is exactly what I did:
Got the head on torqued to spec (other head still off car); took 7.4 pushrod and set it in place; installed rocker arm on rocker guide (along with another rocker just finger snug to keep the guide from moving much); tightening the rocker until it would not wiggle horizontally or vertically or actuate freely; took torque wrench and went to 22ft*lbs, took roughly 70deg;
.Does the lifters being BRAND NEW and I'm assuming not pumped up with oil affect anything? If so, how can I measure with new lifters?
So, I am attempting to check for proper length using the "zero lash -> # of turns to 22ft*lbs" method. The car: 98 z28, stock 806 heads, tsp 228R, LS7 lifters, felpro gasket PN 9284PT, stock rockers. I am using a TSP 7.4in pushrod for the check. I have cylinder at TDC, so definitely on base circle...
I've always used checker springs unless I'm measuring with a solid lifter, otherwise the lifter could partially collapse and skew the measurements. An adj pushrod is only $20, and makes this process considerably easier w/ less guess work.
Last edited by Squirts11; Jan 23, 2011 at 10:05 PM.
I realize now that taking the timing cover back off would be cheap insurance, but I was fairly confident in my method.
Can I just setup one rocker to check for length or do you have to have all rockers/pushrods on and snug?
Also will probably get an adjustable pushrod just to take alot of the guesswork out.
I will be using the wipe method this time around... Anything else I should take into consideration with my setup?
So, after several hours of searching, I think I've begun to understand your post and how I should be checking for pushrod length (Before, I read one post, was a bit hurried, and just tried the method that involved the least $$$, there was no mention of the difference in lifters). I need a weak check spring to counteract the hydraulic lifters' springs so that value is not an issue, where can I buy these?
Can I just setup one rocker to check for length or do you have to have all rockers/pushrods on and snug?
Also will probably get an adjustable pushrod just to take alot of the guesswork out.
I will be using the wipe method this time around... Anything else I should take into consideration with my setup?
Can I just setup one rocker to check for length or do you have to have all rockers/pushrods on and snug?
Also will probably get an adjustable pushrod just to take alot of the guesswork out.
I will be using the wipe method this time around... Anything else I should take into consideration with my setup?
Leave everyting as it is, put the intake pushrod in the motor with no rocker. Rotate the motor until the pushrod goes up and keep a little finger pressure on the pushrod. Then keep turning until the pushrod goes back down (without a little finger pressure the lifter tray will keep it up). Once the pusrhod goes to the bottom, the piston is past the bottom and on the way to the top. Rotate the crank another 1/4 turn past pushrod bottom and then watch carefully for the piston to reach the top. You can use a straw to feel for the piston and a flashlight to see it. Once at the top you are at TDC.
Put in the two pushrods and the rockers. Tighten until the rocker will no longer tick when you lift the tip. If you lift too hard (since lifters are bled) you will compress the plunger in the lifter, so you must be very gentle. Once you just get rid of the tick (if in doubt leave a small amount of tick) then rotate with the torque wrench to 22 lb-ft and count turns. Don't forget, you must account for rocker ratio to obtain preload. I have measured both ways and if done correctly and accounting for turns to torque, they do come out the same. See what you get with this approach.
Wipe Method? Pushrod length has no effect on the wipe pattern unless you are using stud mounted rockers (stock rockers are not stud mounted).
Leave everyting as it is, put the intake pushrod in the motor with no rocker. Rotate the motor until the pushrod goes up and keep a little finger pressure on the pushrod. Then keep turning until the pushrod goes back down (without a little finger pressure the lifter tray will keep it up). Once the pusrhod goes to the bottom, the piston is past the bottom and on the way to the top. Rotate the crank another 1/4 turn past pushrod bottom and then watch carefully for the piston to reach the top. You can use a straw to feel for the piston and a flashlight to see it. Once at the top you are at TDC.
Put in the two pushrods and the rockers. Tighten until the rocker will no longer tick when you lift the tip. If you lift too hard (since lifters are bled) you will compress the plunger in the lifter, so you must be very gentle. Once you just get rid of the tick (if in doubt leave a small amount of tick) then rotate with the torque wrench to 22 lb-ft and count turns. Don't forget, you must account for rocker ratio to obtain preload. I have measured both ways and if done correctly and accounting for turns to torque, they do come out the same. See what you get with this approach.
Leave everyting as it is, put the intake pushrod in the motor with no rocker. Rotate the motor until the pushrod goes up and keep a little finger pressure on the pushrod. Then keep turning until the pushrod goes back down (without a little finger pressure the lifter tray will keep it up). Once the pusrhod goes to the bottom, the piston is past the bottom and on the way to the top. Rotate the crank another 1/4 turn past pushrod bottom and then watch carefully for the piston to reach the top. You can use a straw to feel for the piston and a flashlight to see it. Once at the top you are at TDC.
Put in the two pushrods and the rockers. Tighten until the rocker will no longer tick when you lift the tip. If you lift too hard (since lifters are bled) you will compress the plunger in the lifter, so you must be very gentle. Once you just get rid of the tick (if in doubt leave a small amount of tick) then rotate with the torque wrench to 22 lb-ft and count turns. Don't forget, you must account for rocker ratio to obtain preload. I have measured both ways and if done correctly and accounting for turns to torque, they do come out the same. See what you get with this approach.
1
The first step is to install a solid lifter (i dont have solids so I was thinking of using the check springs i've heard of instead) and an adjustable pushrod. Mark the tip of the valve with a marker
2
Install your rocker arm and set it up with zero lash.
3
Rotate the crankshaft clockwise several times. Remove the rocker arm. The contact pattern of the rocker tip will be where the marker has been wiped away from the valve tip. The pattern should be centered on the valve tip, and as narrow as possible. If it is not, experiment with varying the pushrod length to yield the best pattern.
4
Pushrod Too Long: Notice how the pattern is wide, and shifted to the exhaust side of the valve tip.
5
Pushrod Too Short: Notice how the pattern is wide, and shifted to the intake side of the valve tip.
6
Pushrod Length Correct: Notice how the pattern is narrow and is centered on the valve tip.
Leave everyting as it is, put the intake pushrod in the motor with no rocker. Rotate the motor until the pushrod goes up and keep a little finger pressure on the pushrod. Then keep turning until the pushrod goes back down (without a little finger pressure the lifter tray will keep it up). Once the pusrhod goes to the bottom, the piston is past the bottom and on the way to the top. Rotate the crank another 1/4 turn past pushrod bottom and then watch carefully for the piston to reach the top. You can use a straw to feel for the piston and a flashlight to see it. Once at the top you are at TDC.
Put in the two pushrods and the rockers. Tighten until the rocker will no longer tick when you lift the tip. If you lift too hard (since lifters are bled) you will compress the plunger in the lifter, so you must be very gentle. Once you just get rid of the tick (if in doubt leave a small amount of tick) then rotate with the torque wrench to 22 lb-ft and count turns. Don't forget, you must account for rocker ratio to obtain preload. I have measured both ways and if done correctly and accounting for turns to torque, they do come out the same. See what you get with this approach.
Thanks for the reply, I know I'm talking with no experience but I'm trying to get this right the first time...
Also, found this as well, from '08
You would remove two rockers(1 intake, 1 exhaust). Adjust your pushrod length tool to about 7.350(maybe more maybe less depending on your setup). Reinstall the rocker and tighten to 22 ft.lbs. Loosen the pushrod tool until it contacts the rocker and the rocker has no play between the valve tip and pushrod(zero lash). Remove the tool without turning it and measure it with a caliper or count the turns(each is equal to .050) and add the length of the tool(about 6.8").
Take the length of the tool + the amount of turns + .080(preload) and that is your pushrod length.
Example: 6.8" + .5"(10 turns) + .080 = 7.380...this is from my motor in which I used a 7.375" pushrod.
Hope this helps.
Take the length of the tool + the amount of turns + .080(preload) and that is your pushrod length.
Example: 6.8" + .5"(10 turns) + .080 = 7.380...this is from my motor in which I used a 7.375" pushrod.
Hope this helps.
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You can't correctly establish the wipe pattern with the hydraulic lifter in place and rotating the motor. The plunger will compress and reduce lift. If you have a check spring, you can check the wipe pattern with a dial indicator (a good metal ruler in a pinch) and install the rocker without a pushrod and with the piston down the cylinder rotate the rocker by hand. Here is a link on how to do it but I was using Yella Terra rockers. The link is shows the heads off the car but the same method can be used with the heads installed, just make sure the piston is down out of the way so the valve can open by hand without hitting the piston. Same method also applies to any fixed rocker such as stock: Link
See below.
See below.
Method taken from Cam Guide sticky, as follows
1
The first step is to install a solid lifter (i dont have solids so I was thinking of using the check springs i've heard of instead) and an adjustable pushrod. Mark the tip of the valve with a marker
2
Install your rocker arm and set it up with zero lash.
3
Rotate the crankshaft clockwise several times. Remove the rocker arm. The contact pattern of the rocker tip will be where the marker has been wiped away from the valve tip. The pattern should be centered on the valve tip, and as narrow as possible. If it is not, experiment with varying the pushrod length to yield the best pattern. (This sentence is wrong and will not work on an LS1 unless you are using aftermarket stud mounted rockers such as the Cranes.)
4
Pushrod Too Long: Notice how the pattern is wide, and shifted to the exhaust side of the valve tip.
This is wrong, pushrod length won't change this and the guidance provided is for the small block.
5
Pushrod Too Short: Notice how the pattern is wide, and shifted to the intake side of the valve tip.
This is wrong, pushrod length won't change this and the guidance provided is for the small block.
6
Pushrod Length Correct: Notice how the pattern is narrow and is centered on the valve tip.
Thats sounds about exactly what I did, except replace pushrod/lifter and straw with eyes.
Stupid question, but I'm pretty sure I compressed the lifter trying this the first time, does it just spring back when compression (ie pushrod and rockers) is removed, or does it stick there?
It will spring back to the top and if the lifter is new they are fairly easy to compress so you have to be very gentle in taking measurements so that you don't compress the plunger.
Thanks for the reply, I know I'm talking with no experience but I'm trying to get this right the first time...
Also, found this as well, from '08
What do you think of that method, is it sound? This one sounds a bit less idiot-proof and wouldn't require solid lifters or check springs
1
The first step is to install a solid lifter (i dont have solids so I was thinking of using the check springs i've heard of instead) and an adjustable pushrod. Mark the tip of the valve with a marker
2
Install your rocker arm and set it up with zero lash.
3
Rotate the crankshaft clockwise several times. Remove the rocker arm. The contact pattern of the rocker tip will be where the marker has been wiped away from the valve tip. The pattern should be centered on the valve tip, and as narrow as possible. If it is not, experiment with varying the pushrod length to yield the best pattern. (This sentence is wrong and will not work on an LS1 unless you are using aftermarket stud mounted rockers such as the Cranes.)
4
Pushrod Too Long: Notice how the pattern is wide, and shifted to the exhaust side of the valve tip.
This is wrong, pushrod length won't change this and the guidance provided is for the small block.
5
Pushrod Too Short: Notice how the pattern is wide, and shifted to the intake side of the valve tip.
This is wrong, pushrod length won't change this and the guidance provided is for the small block.
6
Pushrod Length Correct: Notice how the pattern is narrow and is centered on the valve tip.
Thats sounds about exactly what I did, except replace pushrod/lifter and straw with eyes.
Stupid question, but I'm pretty sure I compressed the lifter trying this the first time, does it just spring back when compression (ie pushrod and rockers) is removed, or does it stick there?
It will spring back to the top and if the lifter is new they are fairly easy to compress so you have to be very gentle in taking measurements so that you don't compress the plunger.
Thanks for the reply, I know I'm talking with no experience but I'm trying to get this right the first time...
Also, found this as well, from '08
What do you think of that method, is it sound? This one sounds a bit less idiot-proof and wouldn't require solid lifters or check springs
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