Pushrod question!
10-14-2004, 09:46 PM
#1
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Pushrod question! Doing thehead swap from stock to s2 5.3's got the head on, put the rockers on and tightened them to 20lbs, then a second pass at 24 like ls1howto says to... if i get two fingers on the pushrids i can turn them, is this bad? I cannot turn the rods on the last cylender.
I have a tr224, but its been in for quite some time now so i know i have the right length rods.
will this be ok, or do i need to do something to fix this?
I have a tr224, but its been in for quite some time now so i know i have the right length rods.
will this be ok, or do i need to do something to fix this?
10-14-2004, 09:55 PM
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Now that I look, the only one i *cant* move...to get the rocker to torque down to 24ft lb, its down further then the rest of the rockers.... pictures attatched...
what happened?
it's the second rocker on the #5 piston
what happened?
it's the second rocker on the #5 piston
10-14-2004, 10:00 PM
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Your lifters may have 'pumped down' a little while sitting. You probably won't know for sure until you start it & let it run for a few minutes. But it doesn't sound that far off. Most people have issues the other direction, meaning the valve springs compress as you are tightening the rocker arms....
10-14-2004, 10:04 PM
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thats what its doing... the spring is compressing. that ONE rocker is further down then all the rest... i cant move the pushrod on that one, and i can with all the others...
i havnt rotated the crank at all and i havnt touched the cam...
so most likey everything is fine?
wouldnt the rocker be higher then all the rest if it was pushing?
i havnt rotated the crank at all and i havnt touched the cam...
so most likey everything is fine?
you sure it not just the postion of the cam starting to lift on that one?
10-15-2004, 11:28 AM
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No the pushrod is pressing on the opposite side of the rocker the valve is, so its pressing that side down, which is opening the valve. Right? Or are we talking about two different things?
10-15-2004, 11:30 AM
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That is to say the pushrod is moved by the cam, pressing on the rocker, which in turn compresses the spring and opens the valve. Then when the tension is gone from the rocker because the pushrod has moved over the lobe, the spring brings the rocker back to where it rests.
I think its fine, turn it over and see with a breakover.
I think its fine, turn it over and see with a breakover.
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10-15-2004, 01:03 PM
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Well if the cam has that valve open yes, cause it would push the pushrod up, compressing the spring as I tighten the bolt...
I understand that, but just because the valve is open, why would that mean that I had to crank on the bolt so much longer to get it tight? it's still going in just as far as all the other bolts into the rocker seat and the head... or am I just imagining this? seemed like i had to give that bolt an extra 15 cranks to get it tight to 20lbs
I understand that, but just because the valve is open, why would that mean that I had to crank on the bolt so much longer to get it tight? it's still going in just as far as all the other bolts into the rocker seat and the head... or am I just imagining this? seemed like i had to give that bolt an extra 15 cranks to get it tight to 20lbs
10-15-2004, 03:38 PM
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Sounds to me like that cyl is NOT at TDC when you are tightening that rocker arm. Because if it is, and that is the flat part of the cam, you should be able to 'seat the bolt' without the spring compressing at all. If the spring compresses when you're at TDC, that means the valve will hang open & the engine will run like crap. And maybe kiss the piston.
Are you 100% sure you are at TDC on that cyl? And the rocker arm & pushrod are in the correct positions? They should all be the same!!! Can you measure the valve height? These are new heads, correct? Maybe they screwed up & installed a taller valve on that cyl. Whatever it is, you need to fix this!
Are you 100% sure you are at TDC on that cyl? And the rocker arm & pushrod are in the correct positions? They should all be the same!!! Can you measure the valve height? These are new heads, correct? Maybe they screwed up & installed a taller valve on that cyl. Whatever it is, you need to fix this!
10-15-2004, 09:56 PM
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How can I tell it it's at TDC? All I did was take the old heads off and put the new ones on... I dont understand what could have changed..are you sure it's a problem?
couldn't the engie have stopped with that valve open?
couldn't the engie have stopped with that valve open?
Last edited by jermzz; 10-15-2004 at 10:05 PM.
10-15-2004, 10:15 PM
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Originally Posted by SDC
That is to say the pushrod is moved by the cam, pressing on the rocker, which in turn compresses the spring and opens the valve. Then when the tension is gone from the rocker because the pushrod has moved over the lobe, the spring brings the rocker back to where it rests.
I think its fine, turn it over and see with a breakover.
I think its fine, turn it over and see with a breakover.
10-16-2004, 02:17 PM
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A breakover bar is a tool. You can just put the crank bolt in and turn that with a wrench. Are you pressurizing the cylinder or are you using the Top Dead Center method to install the springs? Are you using the guide of LS1howto.com?
Top dead center method
This method requires you to put the piston at the highest position in the bore, so that when you start to compress the spring, the valve can only drop until it hits the piston. When the piston is at top dead center, the valve can't move very far at all.
There are several ways to accomplish this:
A) You can place a small stick/rod/straw/something into the spark plug hole and have a buddy turn the crankshaft by putting the stock 24mm crank pulley bolt in and turning the bolt with a wrench. You should be able to feel when the piston comes up to the top.
B) This method is a bit more elegant. Rotate your motor over by hand until your cam gear and crank gear are dot to dot like you set them up as earlier. At this position, piston 1 and 6 should be at top dead center. You can change the 4 springs on these 2 cylinders now using the instructions below. After you change those 4, then, rotate the crankshaft a full 90 degrees, and the cam gear dot will turn 45 degrees, as if it is pointing to 7:30 if it were a clock. Now piston 8 and 5 are at the top and can be changed. Rotate another 90 degrees on the crank and your cam gear dot will now be at 9 o'clock. Piston 7 and 4 can now have their springs changed. And FINALLY, rotate the crank another 90 degrees and the cam gear dot will be at 10:30. You can now change your remaining four springs on piston 3 and 2.
Once again, that's 1 & 6, rotate 90, 8 & 5, rotate 90, 7 & 4, rotate 90, 3 & 2.
Thats the top dead center method. You'll need a breakover bar to turn the crank
Top dead center method
This method requires you to put the piston at the highest position in the bore, so that when you start to compress the spring, the valve can only drop until it hits the piston. When the piston is at top dead center, the valve can't move very far at all.
There are several ways to accomplish this:
A) You can place a small stick/rod/straw/something into the spark plug hole and have a buddy turn the crankshaft by putting the stock 24mm crank pulley bolt in and turning the bolt with a wrench. You should be able to feel when the piston comes up to the top.
B) This method is a bit more elegant. Rotate your motor over by hand until your cam gear and crank gear are dot to dot like you set them up as earlier. At this position, piston 1 and 6 should be at top dead center. You can change the 4 springs on these 2 cylinders now using the instructions below. After you change those 4, then, rotate the crankshaft a full 90 degrees, and the cam gear dot will turn 45 degrees, as if it is pointing to 7:30 if it were a clock. Now piston 8 and 5 are at the top and can be changed. Rotate another 90 degrees on the crank and your cam gear dot will now be at 9 o'clock. Piston 7 and 4 can now have their springs changed. And FINALLY, rotate the crank another 90 degrees and the cam gear dot will be at 10:30. You can now change your remaining four springs on piston 3 and 2.
Once again, that's 1 & 6, rotate 90, 8 & 5, rotate 90, 7 & 4, rotate 90, 3 & 2.
Thats the top dead center method. You'll need a breakover bar to turn the crank
10-16-2004, 04:32 PM
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If you still had a head off, you could find TDC for all 4 cyl on the other side very easily. I assume they are both back on now? So you will need to use the above method. Once you find TDC on any cyl you can mark the crank pulley & use that as your degree wheel (90* or 3:00, 180* or 6:00, 270* or 9:00).
Another way is to put your finger over a spark plug hole & turn the engine until it quits pushing air gainst your finger. Watch the valve springs on the cyl to see where they BOTH quit moving. When you get both situations to coincide, you should be very close to TDC.
As much of a pain as it is, because you replaced the heads, I would check every cly to make sure you're OK. Normally if you just replaced a cam or something & a few of them are good, you can just tighten the rest of them down. And you will see what is happening now. No lash, springs compressing, pushrods not turning, etc on some of the cylinders. But new heads create all new geometry so you should check them all.
Another way is to put your finger over a spark plug hole & turn the engine until it quits pushing air gainst your finger. Watch the valve springs on the cyl to see where they BOTH quit moving. When you get both situations to coincide, you should be very close to TDC.
As much of a pain as it is, because you replaced the heads, I would check every cly to make sure you're OK. Normally if you just replaced a cam or something & a few of them are good, you can just tighten the rest of them down. And you will see what is happening now. No lash, springs compressing, pushrods not turning, etc on some of the cylinders. But new heads create all new geometry so you should check them all.
