Does any one know the stock pushrod length?
Thread Starter
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1st Gear Member
Joined: Sep 2009
Posts: 102
From: Claremont, North Carolina
Does any one know the stock pushrod length?
Does any one know the stock pushrod length for a 1999 Pontiac Grand am GT.
Im doing that head, manifold and rocker swap into my camaro and i need new push rods. Does anyone know the length? OR maybe a universal length or even better a length that wont hurt my engine but give it hp?
Im doing that head, manifold and rocker swap into my camaro and i need new push rods. Does anyone know the length? OR maybe a universal length or even better a length that wont hurt my engine but give it hp?
April 2011 ROTM
Joined: Mar 2009
Posts: 22,022
From: Tokeland, Washington
ROTM Winner's Club
would be best to mesure. this is something i got from lloyd at elliotts portworks for my lt1, i had to separate the pictures to post so they are at the bottom. hope u can make sence of it.
PR length is something that you need to check to get the EXACT length. Use an adjustable PR checker and start at 7.100" and adjust the length until you get the wear pattern most centered in the valve. Go .050" shorter and watch the wear pattern move. If it gets worse, go .050 longer. It could be anywhere from 7.00 to 7.250 depending on everything done but a 7.100" (Trik Flow 21407100) is what I suggest for people that do not know how (or do not wanna take the time) to do this.
The following is a method of verifying proper valve train geometry. After you have estimated the required pushrod length using a Pushrod Length Checker, use this method to verify that the valve train geometry is correct (using the rockers you are using in your engine):
1
The first step is to install a solid lifter 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.
PR length is something that you need to check to get the EXACT length. Use an adjustable PR checker and start at 7.100" and adjust the length until you get the wear pattern most centered in the valve. Go .050" shorter and watch the wear pattern move. If it gets worse, go .050 longer. It could be anywhere from 7.00 to 7.250 depending on everything done but a 7.100" (Trik Flow 21407100) is what I suggest for people that do not know how (or do not wanna take the time) to do this.
The following is a method of verifying proper valve train geometry. After you have estimated the required pushrod length using a Pushrod Length Checker, use this method to verify that the valve train geometry is correct (using the rockers you are using in your engine):
1
The first step is to install a solid lifter 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.
Thread Starter
|
1st Gear Member
Joined: Sep 2009
Posts: 102
From: Claremont, North Carolina
would be best to mesure. this is something i got from lloyd at elliotts portworks for my lt1, i had to separate the pictures to post so they are at the bottom. hope u can make sence of it.
PR length is something that you need to check to get the EXACT length. Use an adjustable PR checker and start at 7.100" and adjust the length until you get the wear pattern most centered in the valve. Go .050" shorter and watch the wear pattern move. If it gets worse, go .050 longer. It could be anywhere from 7.00 to 7.250 depending on everything done but a 7.100" (Trik Flow 21407100) is what I suggest for people that do not know how (or do not wanna take the time) to do this.
The following is a method of verifying proper valve train geometry. After you have estimated the required pushrod length using a Pushrod Length Checker, use this method to verify that the valve train geometry is correct (using the rockers you are using in your engine):
1
The first step is to install a solid lifter 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.
PR length is something that you need to check to get the EXACT length. Use an adjustable PR checker and start at 7.100" and adjust the length until you get the wear pattern most centered in the valve. Go .050" shorter and watch the wear pattern move. If it gets worse, go .050 longer. It could be anywhere from 7.00 to 7.250 depending on everything done but a 7.100" (Trik Flow 21407100) is what I suggest for people that do not know how (or do not wanna take the time) to do this.
The following is a method of verifying proper valve train geometry. After you have estimated the required pushrod length using a Pushrod Length Checker, use this method to verify that the valve train geometry is correct (using the rockers you are using in your engine):
1
The first step is to install a solid lifter 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.
Can anyone just tell me. I'm just getting them for a head swap. Thanks for the great detail and ill be sure to do this next time i get a chance but i just need to know the exact length right now. I cant buy push rods and find out they're the wrong size. then im out that money. I just need to know the right ones to buy. Thanks.
April 2011 ROTM
Joined: Mar 2009
Posts: 22,022
From: Tokeland, Washington
ROTM Winner's Club
its like 15 bucks for a length checker. changing the head style, changing rocker arm style (i think stock are 1.5 to 1) and changing the head gasket compressed thickness can change the exact pushrod length. it would be best to measure, not sure anyone can give u a correct answer without guessing.
Thread Starter
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1st Gear Member
Joined: Sep 2009
Posts: 102
From: Claremont, North Carolina
its like 15 bucks for a length checker. changing the head style, changing rocker arm style (i think stock are 1.5 to 1) and changing the head gasket compressed thickness can change the exact pushrod length. it would be best to measure, not sure anyone can give u a correct answer without guessing.
Oh, thanks, but i have one question thats killing me....How come you couldnt just put new ones that are stock length with the head they came with? is it cuz thier on a diff motor now?
April 2011 ROTM
Joined: Mar 2009
Posts: 22,022
From: Tokeland, Washington
ROTM Winner's Club
i dont know the dimensions of the heads. if they are in fact the same then stock should work but there may be some varables in there to. what were the dimensions of the blocks? the distance from the cam to the rocker may be different. has the newer heads been milled and how much? if they have been milled to flatten them or increase compression it can change the distance between the rocker and the cam. with the roller rockers they need to be centered on the valve stem or u can end up with bent valves. are u having the heads milled down, and using a thinner head gasket for more compression. might be a good time to.
Thread Starter
|
1st Gear Member
Joined: Sep 2009
Posts: 102
From: Claremont, North Carolina
i dont know the dimensions of the heads. if they are in fact the same then stock should work but there may be some varables in there to. what were the dimensions of the blocks? the distance from the cam to the rocker may be different. has the newer heads been milled and how much? if they have been milled to flatten them or increase compression it can change the distance between the rocker and the cam. with the roller rockers they need to be centered on the valve stem or u can end up with bent valves. are u having the heads milled down, and using a thinner head gasket for more compression. might be a good time to.
this is really all im going on.
" I made sure I got a set of heads used on the 1999+ Grand Am GT, which featured bigger valves and roller rocker arms built in, as well as larger runners and ports on the plenum as well as an increased plenum size."
Thread Starter
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1st Gear Member
Joined: Sep 2009
Posts: 102
From: Claremont, North Carolina
Like i said i would aquire them from a junk yard (pull-a-part) so i have no idea if they are or not.