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Idea for measuring lash pads


Guest Anonymous

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Guest Anonymous

I posted this on zcar but I thought I would double up because I would like to get these ordered today :?:

 

I am setting up my p79. I had a valve job done, shaved .08", shimmed .075" with valves from a 76. Also I have a 260 cam and rockers reground from Delta. so I had no idea what I was going to be looking for as far as lash pad thickness.

 

I ran the test and all the stock lash pads kept the wipe pattern on the rocker. They are biased toward the pivot point which I read may actually be ok because it increases the lift a bit. I used a sharpy to color the rocker arem black, then ran the cam all the way around. The remaining black area on the rocker was about twice as wide on the valve side as the pivot side. I guess my first question is, should I even get different lash pads. My only concern is I'm using stock springs.

 

Second, I had an idea to measure for lash pads that I need to confirm. In my head this takes into consideration all of the variables but I want the pros that have done it before to confirm if this would work.

 

I colored the rocker and adjusted the pivot disregarding valve clearences untill the wipe pattern was in the middle of the rocker. This obviously leaves me with a larger gap than called for. I then try a feeler guage untill I find what the gap is. In the case of the arm I measured .75mm. I then subtract the cold clearence spec .17mm. This gives me a delta of .58mm. Am I correct in thinking that I need to get a lash pad that is .58mm thicker than a stock lash pad???

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Guest Anonymous

should I be concerned with the springs? Everything I have read suggests that 260 lift is all you want to do for stock springs. The cam is 260 right now. Would that be a problem?

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Avernet, your measures to restore the valvetrain geometry once the head was shaved were good but the lash pad problem now is due to the reground cam vs a new cam (base circle). I know that to drop the cam down would be putting slack back into the chain, but you could potentially use the stock lash pads with the longer valves you've already installed if you remove tower shims of the right amount. This suggestion is intended for if 16 new lash pads are too expensive. DAW

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Full compression is what binding is. If there is no room for the valve to open and you have more cam to go, then you get what is called coil bind, and it will wear out your cam.

 

Stock set-ups typically can take about .460 lift before experiencing coil bind, but again, I have run .490 lift cams with no problems, and then other one's with, it just depends.

 

As long as you have "some" space between the spring coils with the cam lobe centered and the valve opened all the way, you should be fine. If you are concerned about it, buy a set of springs and retainers from Motorsport and be done with it.

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Guest Anonymous

gotcha. I will check it when I get home.

 

Unless they are binding I think I'll stick with the originals. Worse case I'll just need to switch to the aftermarket lash pads right?

 

I live 10 min. from courtesy nissan so getting new ones shouldn't be that hard.

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