The famous pushrod length question...
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From: Central,NJ
Now, to add to the discussion. Rocker ratio is also a factor, even staying with the same brand/product line. I have found higher ratio rockers require longer PR length.
As for the centering of the valve pattern, forget it. When the geometry is correct it will fall some where on the exhaust third of the valve tip. But you need to check the roller tip is not running off the edge of the stem. If it is and the geometry is correct then you need to compromise with either more preload(hyd.) or a shorter pushrod.
As for the centering of the valve pattern, forget it. When the geometry is correct it will fall some where on the exhaust third of the valve tip. But you need to check the roller tip is not running off the edge of the stem. If it is and the geometry is correct then you need to compromise with either more preload(hyd.) or a shorter pushrod.
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this, IMHO, is a good description of what pattern and position you should get
https://www.lunatipower.com/Tech/Val...nGeometry.aspx
https://www.lunatipower.com/Tech/Val...nGeometry.aspx
Other than that, I have used .060 lash caps before without having to change PR length. The sweep was just a touch wider, but wasn't enough to warrant getting different PR's. I guess if you really want to eek out as much efficiency you can then maybe get different length PR's for a higher rocker ratio, but most everyone I've ever encountered have always stuck with stock length.
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Let us stop for a second and consider the basic architecture we are working with was born in the 50s with sub-.400 lift, eventually GM was using a bit more but most OEM cams for the gen 1-2 architecture are say .470 and under. We are talking about setting stuff up way way outside the range this architecture was designed for.
Which is why you have folks saying narrowest sweep is unlikely to be center, we are asking it to handle things well outside what GM designed it for. In a perfect world the pattern would be center and narrow, but since we are using different ratio rockers and 35%+ more lift than the original architecture it just isn't going to happen.
I also think folks get far too worked up over it, the valvetrain is adjustable afterall.
Basically pick what you feel is best be it center or narrow or some balance of the two and run with it. The valvetrain is again adjustable.
Only time I have ever heard of pushrod length induced damage in an LT1 was a checkbook mechanic put in pushrods so long he ran the roller tips off the edge of the valve tip and RAN IT busting a bunch of the guides!
Long as you are conscience of pattern width and location on valve I think you will do just fine.
Non adjustable valvetrain like the LS1 variants are going to be more sensitive and I think people hear about that and presume the same level of sensitivity applies to this application. IMO it does not.
Which is why you have folks saying narrowest sweep is unlikely to be center, we are asking it to handle things well outside what GM designed it for. In a perfect world the pattern would be center and narrow, but since we are using different ratio rockers and 35%+ more lift than the original architecture it just isn't going to happen.
I also think folks get far too worked up over it, the valvetrain is adjustable afterall.
Basically pick what you feel is best be it center or narrow or some balance of the two and run with it. The valvetrain is again adjustable.
Only time I have ever heard of pushrod length induced damage in an LT1 was a checkbook mechanic put in pushrods so long he ran the roller tips off the edge of the valve tip and RAN IT busting a bunch of the guides!
Long as you are conscience of pattern width and location on valve I think you will do just fine.
Non adjustable valvetrain like the LS1 variants are going to be more sensitive and I think people hear about that and presume the same level of sensitivity applies to this application. IMO it does not.
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Now, to add to the discussion. Rocker ratio is also a factor, even staying with the same brand/product line. I have found higher ratio rockers require longer PR length.
As for the centering of the valve pattern, forget it. When the geometry is correct it will fall some where on the exhaust third of the valve tip. But you need to check the roller tip is not running off the edge of the stem. If it is and the geometry is correct then you need to compromise with either more preload(hyd.) or a shorter pushrod.
As for the centering of the valve pattern, forget it. When the geometry is correct it will fall some where on the exhaust third of the valve tip. But you need to check the roller tip is not running off the edge of the stem. If it is and the geometry is correct then you need to compromise with either more preload(hyd.) or a shorter pushrod.
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From: Central,NJ
Eh, most likely because a lot of the self-righteous D's that often used this forum for a personal blog are gone.
Other than that, I have used .060 lash caps before without having to change PR length. The sweep was just a touch wider, but wasn't enough to warrant getting different PR's. I guess if you really want to eek out as much efficiency you can then maybe get different length PR's for a higher rocker ratio, but most everyone I've ever encountered have always stuck with stock length.
Other than that, I have used .060 lash caps before without having to change PR length. The sweep was just a touch wider, but wasn't enough to warrant getting different PR's. I guess if you really want to eek out as much efficiency you can then maybe get different length PR's for a higher rocker ratio, but most everyone I've ever encountered have always stuck with stock length.
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From: Central,NJ
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Ahh. Is your cam spec'd for it? The ramp speed at the valve is going to be awesome. Hope your springs are up to the task or the cam is spec'd for em.
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From: Central,NJ