PUSHROD LENGTH
Launching!
Joined: Dec 2001
Posts: 210
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From: Homestead
Re: PUSHROD LENGTH I have the same heads I am running hardened pushrods <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> Works fine ! :} you don't want to get the shorter ones because at high RPMS they will flutter and wont allow the valve to open all the way and you will lose power
TECH Fanatic
Joined: Nov 2001
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From: SW Florida
Re: PUSHROD LENGTH It's up to you, but you need to remember this; If you are still running the same factory cam which means the cam's base circle is still the stock dimension, that 30 thousands takin off the head would require a pushrod that was .030" shorter in order to maintain the exact preload you had before.
Well, the aftermarket pushrods come in .050" increments. A .050" shorter rod would get you closer to your ideal preload than a stock rod, given that you milled .030" off the head.
I would buy the shorter 7.35" rods if it were up to me.
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Now, if you [also] had an aftermarket cam, these cams normally have aprox a .030" smaller base circle (cam centerline to lobe heal distance) than the factory LS1 cam. If that was the case, you would be better off with the stock 7.40" pushrod with your milled heads. In fact, with the milled heads and aftermarket cam, your lifter preload would not change at all with stock length rods.
Ron,
Well, the aftermarket pushrods come in .050" increments. A .050" shorter rod would get you closer to your ideal preload than a stock rod, given that you milled .030" off the head.
I would buy the shorter 7.35" rods if it were up to me.
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Now, if you [also] had an aftermarket cam, these cams normally have aprox a .030" smaller base circle (cam centerline to lobe heal distance) than the factory LS1 cam. If that was the case, you would be better off with the stock 7.40" pushrod with your milled heads. In fact, with the milled heads and aftermarket cam, your lifter preload would not change at all with stock length rods.
Ron,
TECH Fanatic
Joined: Nov 2001
Posts: 1,975
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From: SW Florida
Re: PUSHROD LENGTH shadowSS is correct that stock length rods work great for him because he has the aftermarket cam [and] milled heads.
In your case, you never mentioned an aftermarket cam. Again, with the [stock] cam and .030" milled heads, get a set of 7.35" rods.
Ron,
In your case, you never mentioned an aftermarket cam. Again, with the [stock] cam and .030" milled heads, get a set of 7.35" rods.
Ron,
TECH Fanatic
Joined: Nov 2001
Posts: 1,975
Likes: 2
From: SW Florida
Re: PUSHROD LENGTH I have not read anywhere where GM listed the stock lifter preload, however, you can use the procedure shown below if you think you have a preload problem.
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Turning the engine, bring the exhaust pushrod on any cylinder up until it is at peak lift (valve fully open). Now, install a pushrod on the intake of that cyl. (this valve will be fully closed) and slowly turn the rocker arm bolt down until the lifter is at "zero lash" (pushrod will start getting harder to turn when being spun with your fingers). Mark the bolt with a marker. Then count how many turns it takes to completely tighten the bolt to 22 FT/LB. From what I have read, the bolt should have turned between 1 to 1 1/4 turns for the acceptable GM lifter preload. One person on this board stated that 1 full turn of the rocker bolt equals .049" during his measurment.
Ron,
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Turning the engine, bring the exhaust pushrod on any cylinder up until it is at peak lift (valve fully open). Now, install a pushrod on the intake of that cyl. (this valve will be fully closed) and slowly turn the rocker arm bolt down until the lifter is at "zero lash" (pushrod will start getting harder to turn when being spun with your fingers). Mark the bolt with a marker. Then count how many turns it takes to completely tighten the bolt to 22 FT/LB. From what I have read, the bolt should have turned between 1 to 1 1/4 turns for the acceptable GM lifter preload. One person on this board stated that 1 full turn of the rocker bolt equals .049" during his measurment.
Ron,
