Bent Push Rods
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Joined: Apr 2007
Posts: 83
From: South Carolina
Over the past couple of months, several guys have had problems with self-aligning rockers. they even posted photos of the damage caused and with a rocker sitting on the side of a valve spring. Also, I've recently seen a couple of photos where the self-aligning guides were actually riding on the spring retainer. Those are the main reasons I now recommend NON self aligning rocker arms when guys post asking which way to go.
I now recommend NSA rockers in spite of the responses I've read from posters saying "I've been running self-aligning rockers since the beginning of time with no problem", LOL It only takes "one time" and that "one time" seems to be popping up more and more lately.
We still need to know the exact procedure you followed when you set the lifter preload. Could be that something in how you did it will give us a clue.
Also, it would be helpful if you could post some photos of your valve train, close enough so we can see all the clearances we've mentioned so far.
I once calculated the amount of cam timing difference the movement of one gear tooth causes but I can't for the life of me remember the numbers. Chalk that up to 'old age' I guess.
Keep us posted and we'll solve this.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!
I now recommend NSA rockers in spite of the responses I've read from posters saying "I've been running self-aligning rockers since the beginning of time with no problem", LOL It only takes "one time" and that "one time" seems to be popping up more and more lately.
We still need to know the exact procedure you followed when you set the lifter preload. Could be that something in how you did it will give us a clue.
Also, it would be helpful if you could post some photos of your valve train, close enough so we can see all the clearances we've mentioned so far.
I once calculated the amount of cam timing difference the movement of one gear tooth causes but I can't for the life of me remember the numbers. Chalk that up to 'old age' I guess.
Keep us posted and we'll solve this.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!
when changing springs
Installing rockers
rocker contact
I think I was on #6 when I tgought I was on #1 when setting rockers or off somehow.
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Joined: Jan 2006
Posts: 325
From: Back in the US of F'in A
I sincerely doubt that the timing marks being off a tooth is going to cause piston contact with the valves and bend the pushrods...especially since he replaced them with a set of stock replacements and didn't have a repeat of the problem. Many people retard or advance their cams 5 degrees to modify the power band....a single tooth on the cam sprocket is about 10 degrees if I remember correctly. The cam being installed incorrectly will cause it to run poorly...I've seen it more than once....and that will be compounded by the lack of a tune.
By all means check the cam phasing...you can't go wrong by checking. However, that alone didn't cause bent pushrods. Too tight or too loose on the lifter preload is still the likely cause. And I'm still betting on too loose as to get them to bend on too tight you'd have to reach coil bind to 'stop' the rocker.
As Jake mentioned, we'll help get you the set up right under the valve covers....
By all means check the cam phasing...you can't go wrong by checking. However, that alone didn't cause bent pushrods. Too tight or too loose on the lifter preload is still the likely cause. And I'm still betting on too loose as to get them to bend on too tight you'd have to reach coil bind to 'stop' the rocker.
As Jake mentioned, we'll help get you the set up right under the valve covers....
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Joined: Jan 2006
Posts: 325
From: Back in the US of F'in A
Mike
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Joined: Apr 2007
Posts: 83
From: South Carolina
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Posts: 549
From: Lancaster, Texas
Camera angle?? I doubt it, looks extremely off to me, too. More than the camera angle could account for.
To clear this us, post some more shots taken from an improved angle.
For me the problem with being confident that installing the cam gear one-tooth-off and resulting in 16 bent pushrods is I've never experienced it. So I tried to apply logic to this issue and what I came up with is that only 8 valves would have such a reduced amount of clearance to possibly cause your problem.
As I wrote before, if the cam was installed one-tooth-off, only 8 valves would have reduced piston to valve clearance while the other 8 would have increased clearance. Which valves would have the decreased clearance would depend on which way the gear was wrongly installed.
But, now, if you factor in the wrong length pushrods, I can't say what the result would be. New territory for me.
Best we can do is go back to square one, brain-storm this and verify everything having to do with valve train geometry. Something tells me there's more than one thing going on here.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
To clear this us, post some more shots taken from an improved angle.
For me the problem with being confident that installing the cam gear one-tooth-off and resulting in 16 bent pushrods is I've never experienced it. So I tried to apply logic to this issue and what I came up with is that only 8 valves would have such a reduced amount of clearance to possibly cause your problem.
As I wrote before, if the cam was installed one-tooth-off, only 8 valves would have reduced piston to valve clearance while the other 8 would have increased clearance. Which valves would have the decreased clearance would depend on which way the gear was wrongly installed.
But, now, if you factor in the wrong length pushrods, I can't say what the result would be. New territory for me.
Best we can do is go back to square one, brain-storm this and verify everything having to do with valve train geometry. Something tells me there's more than one thing going on here.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
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What "back to the drawing board" ? There was no board. Hell there wasn't even chalk.
Check the full travel of the valve until it binds with a dial indicator.
Then check the full travel of the push rod with the dial indicator.
I'll give you 3 guesses what you're gona find and the first 2 don't count.
Don't forget the multiplier of the rockers.
Check the full travel of the valve until it binds with a dial indicator.
Then check the full travel of the push rod with the dial indicator.
I'll give you 3 guesses what you're gona find and the first 2 don't count.
Don't forget the multiplier of the rockers.
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Joined: Apr 2007
Posts: 549
From: Lancaster, Texas
You have to view the rocker arm from the side to see how the rocker arm is riding on the valve stem. It's hard to see the roller, but use the pin that holds the roller to the rocker. The pin's centered on the roller, so when you look at the center of the pin you've found the center of the roller.
With the lifter on the base circle of the cam lobe, that pin should be slightly INBOARD, (closer the intake manifold). At half valve lift the pin should be centered over the rocker and at full valve lift the pin should be slightly OUTBOARD.
Then it returns to being centered when the valve is half closed and finally returning to the INBOARD position when the lifter is again on the base circle of the cam lobe.
So, if you don't mind, could you take a shot directly from the side of the rocker with no angle? I don't want to cause you this extra work unnecessarily, but it's important that we get the pushrod length correct.
Thanks,
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduaton Day Parade 20 May 2010!!!
With the lifter on the base circle of the cam lobe, that pin should be slightly INBOARD, (closer the intake manifold). At half valve lift the pin should be centered over the rocker and at full valve lift the pin should be slightly OUTBOARD.
Then it returns to being centered when the valve is half closed and finally returning to the INBOARD position when the lifter is again on the base circle of the cam lobe.
So, if you don't mind, could you take a shot directly from the side of the rocker with no angle? I don't want to cause you this extra work unnecessarily, but it's important that we get the pushrod length correct.
Thanks,
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduaton Day Parade 20 May 2010!!!
Last edited by JAKEJR; Nov 29, 2009 at 12:31 PM.
Thread Starter
Registered User
Joined: Apr 2007
Posts: 83
From: South Carolina
You have to view the rocker arm from the side o see how the rocker arm is riding on the valve stem. It's hard to see the roller, but use the pin that holds the roller to the rocker. The pin's centered on the roller, so when you look at the center of the pin you've found the center of the roller.
With the lifter on the base circle of the cam lobe, that pin should be slightly INBOARD, (closer the intake manifold). At half valve lift the pin should be centered over the rocker and at full valve lift the pin should be slightly OUTBOARD.
Then it returns to being centered when the valve is half closed and finally returning to the INBOARD position when the lifter is again on the base circle of the cam lobe.
So, if you don't mind, could you take a shot directly from the side of the rocker with no angle? I don't want to cause you this extra work unnecessarily, but it's important that we get the pushrod length correct.
Thanks,
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduaton Day Parade 20 May 2010!!!
With the lifter on the base circle of the cam lobe, that pin should be slightly INBOARD, (closer the intake manifold). At half valve lift the pin should be centered over the rocker and at full valve lift the pin should be slightly OUTBOARD.
Then it returns to being centered when the valve is half closed and finally returning to the INBOARD position when the lifter is again on the base circle of the cam lobe.
So, if you don't mind, could you take a shot directly from the side of the rocker with no angle? I don't want to cause you this extra work unnecessarily, but it's important that we get the pushrod length correct.
Thanks,
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduaton Day Parade 20 May 2010!!!
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