Pushrod length?
Thread Starter
Pro
Joined: Oct 2005
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From: SW Missouri
Pushrod length?
I’m measuring for pushrods for my 05 LS2 Corvette for the new heads.
Things I’ve changed….
Currently have cyl head and new gasket snug(not torqued) on engine.
-1.8 roller rockers from 1.7
-64 cc chambers from 65cc on the Gen X 225 heads.
-.040 Cometic head gasket
-228/232 112 LSA .600 cam
When I check intake rocker on base circle with pushrod measuring tool it’s 14.5 turns.
14.5 X .050 = .725 + 6.80 = 7.525 pushrod length.
Sound correct?
I got 1 1/8 turn to 22 lb ft torque for rocker bolt.
**FYI Trick Flow states 7.500 pushrods for their Gen X 225 LS2 top end kit with 1.7 roller rockers**
Things I’ve changed….
Currently have cyl head and new gasket snug(not torqued) on engine.
-1.8 roller rockers from 1.7
-64 cc chambers from 65cc on the Gen X 225 heads.
-.040 Cometic head gasket
-228/232 112 LSA .600 cam
When I check intake rocker on base circle with pushrod measuring tool it’s 14.5 turns.
14.5 X .050 = .725 + 6.80 = 7.525 pushrod length.
Sound correct?
I got 1 1/8 turn to 22 lb ft torque for rocker bolt.
**FYI Trick Flow states 7.500 pushrods for their Gen X 225 LS2 top end kit with 1.7 roller rockers**
Last edited by rc51racer; Mar 28, 2022 at 11:17 AM.
Thread Starter
Pro
Joined: Oct 2005
Posts: 700
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From: SW Missouri
Old LS2 lifters I made into solid lifters by taking apart and flipping plunger. Will be adding LS7 lifters for final build.
forgot to mention I got 1 1/8 turn to 22 lb ft torque for rocker bolt.
forgot to mention I got 1 1/8 turn to 22 lb ft torque for rocker bolt.
Last edited by rc51racer; Mar 28, 2022 at 09:53 AM.
Le Mans Master
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From: Out back
LS7 lifters have .200 plunger travel. If TFS says run 7.5s and your measurements are giving you 7.525, you'll be fine with 7.5s.
Side note: I would use an old head gaskets if you have one and fully torque the head. Without the gasket crushed down to spec, your measurements will be off by that crush dimension.
Side note: I would use an old head gaskets if you have one and fully torque the head. Without the gasket crushed down to spec, your measurements will be off by that crush dimension.
Last edited by Pb82 Ronin; Mar 28, 2022 at 11:52 AM.
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,149
From: SW Florida
2021 C6 of the Year Finalist - Modified
Yup ... and .200" is a lot of available travel .... Get the preload somewhere in the middle (.070" - .120") and you will be fine.
BTW ... Using 1.8 ratio rocker arms, this is what the bolt turns will get you for preload (starting at zero preload)
.
BTW ... Using 1.8 ratio rocker arms, this is what the bolt turns will get you for preload (starting at zero preload)
.
Last edited by Turbo6TA; Mar 29, 2022 at 09:18 AM.
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Race Director
Joined: Mar 2011
Posts: 13,262
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From: SW Florida
2021 C6 of the Year Finalist - Modified
And, BTW, I am also using 1.8 ratio rocker arms and an aftermarket cam in my LS3 ... At .090" lifter preload, the valvetrain noise is very minimal.
Very quiet with the stock cam and 1.8 ratio rocker arms, but still pretty quiet after the aftermarket cam was installed.
Again, all you need is somewhere in the middle of zero and 200 thousands preload ... .090" worked good for me.
Very quiet with the stock cam and 1.8 ratio rocker arms, but still pretty quiet after the aftermarket cam was installed.
Again, all you need is somewhere in the middle of zero and 200 thousands preload ... .090" worked good for me.
Thread Starter
Pro
Joined: Oct 2005
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From: SW Missouri
I’m actually using the turn method to figure preload after finding 0 lash. The way I understand it that gets my lifter preload figured in without adding it in. I’m at 1 1/8 turn on rocker bolt after 0 lash. Correct?
Le Mans Master
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From: Out back
They're pedestal rockers man. The torque spec is correct number of turns. Why make it hard on yourself? Torque your head down on an old gasket and do this:
1) Get the cam on the base circle
2) Install your PR length checker as collapsed as it will go (that you can still operate it)
3) TORQUE rocker bolt to desired TQ spec (22 ft lbs)
4) Adjust PR to zero lash (you may have to remove and retorque the bolt to accomplish this)
5) When you get zero lash with the rocker bolt at 22 ft lbs, measure your PR.
6) Add desired "lifter pre-load" to that length and order your PR's.
7) Open a beer and wait for FedEx to deliver your PRs.
1) Get the cam on the base circle
2) Install your PR length checker as collapsed as it will go (that you can still operate it)
3) TORQUE rocker bolt to desired TQ spec (22 ft lbs)
4) Adjust PR to zero lash (you may have to remove and retorque the bolt to accomplish this)
5) When you get zero lash with the rocker bolt at 22 ft lbs, measure your PR.
6) Add desired "lifter pre-load" to that length and order your PR's.
7) Open a beer and wait for FedEx to deliver your PRs.
Last edited by Pb82 Ronin; Mar 29, 2022 at 05:26 PM.
Thread Starter
Pro
Joined: Oct 2005
Posts: 700
Likes: 75
From: SW Missouri
They're pedestal rockers man. The torque spec is correct number of turns. Why make it hard on yourself? Torque your head down on an old gasket and do this:
1) Get the cam on the base circle
2) Install your PR length checker as collapsed as it will go (that you can still operate it)
3) TORQUE rocker bolt to desired TQ spec (22 ft lbs)
4) Adjust PR to zero lash (you may have to remove and retorque the bolt to accomplish this)
5) When you get zero lash with the rocker bolt at 22 ft lbs, measure your PR.
6) Add desired "lifter pre-load" to that length and order your PR's.
7) Open a beer and wait for FedEx to deliver your PRs.
1) Get the cam on the base circle
2) Install your PR length checker as collapsed as it will go (that you can still operate it)
3) TORQUE rocker bolt to desired TQ spec (22 ft lbs)
4) Adjust PR to zero lash (you may have to remove and retorque the bolt to accomplish this)
5) When you get zero lash with the rocker bolt at 22 ft lbs, measure your PR.
6) Add desired "lifter pre-load" to that length and order your PR's.
7) Open a beer and wait for FedEx to deliver your PRs.
that finally worked and made sense. I was trying to combine this method and the “turn” method that Richard Holder has a video on.
So what I need for PR length is 7.500
Le Mans Master
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