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PostPosted: Tue Dec 10, 2019 3:18 pm 
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Protech Racing wrote:
If the BOP is based upon estimated power output from certain head designs and valve lift/ resulting flow, the checking method should be consistent with the dynamic actual valve timing events.

Or we could simply add .012 valve lift value to any pushrod engine spec line.


Or you could send some of us back to the cam shop, no? Couldn't I run a bigger cam to match the lash I no longer have to worry about?


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PostPosted: Wed Dec 11, 2019 4:57 am 
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Just to make I'm getting this, we're arguing over 10 thousands of an inch of cam lash variance on cold engines, of varying designs and across 60 years of development, and how that effects BOP, right...?

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PostPosted: Wed Dec 11, 2019 5:57 am 
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My point is that the 60 yrs of valve train development can be equalized by checking the lift at the valve, as raced. That is all .

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PostPosted: Wed Dec 11, 2019 7:58 am 
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While I can't argue that we might technically measure a difference in as raced conditions, I'm not sure I see an imbalance or competitive issue to solve.

I'm not a fan of making changes if we don't have a reason to (see also Runoffs qualification criteria musical chairs fiasco).

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PostPosted: Wed Dec 11, 2019 10:31 am 
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Open Brakes: Hell no that's expensive and might possibly upset the balance of power
.012 cam lash: Hell yes I'm just making things fair. If you have to build a new engine to take advantage of it, too bad.

???????????????????????????????????????????????????????????

Silly Season you are my favorite!


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PostPosted: Wed Dec 11, 2019 10:53 am 
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blamkin86 wrote:
Open Brakes: Hell no that's expensive and might possibly upset the balance of power
.012 cam lash: Hell yes I'm just making things fair. If you have to build a new engine to take advantage of it, too bad.

???????????????????????????????????????????????????????????

Silly Season you are my favorite!


You all need to stop getting sidetracked. Its all about the box rule so we can buy new wheels and tires and start modifying fenders to fit them. :lol:

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PostPosted: Wed Dec 11, 2019 11:35 am 
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blamkin86 wrote:
Silly Season you are my favorite!
:applause: :doh: :eh: :hand: :whistle:

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PostPosted: Wed Dec 11, 2019 3:01 pm 
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L series Nissan engines get to measure "as raced" in prod. Ask for your specific engine line if you think it is necessary.

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PostPosted: Wed Dec 11, 2019 3:44 pm 
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Protech Racing wrote:
Why? Because many modern engines can run at zero or very little lash. This increases the effective cam lift.
The pushrod engines with flat tappets need maybe 12 to 20 thou lash to keep the cam from galling. This reduces the valve lift by the lash amount.
The spec lines require a certain max lift and those engines may have the same spec line lift but the actual lift varies the amount equal to their respective lash values.
450lift cam that has a lash of .015 really has a lift at the valve of .435.
450 lift cam with zero lash has a lift of 450 .


Builders were using the very little lash method on LS based engines in Daytona Prototypes. They had to heat the engine up first before starting.

If you’re going to argue hypotheticals, might as well include pushrod engines being engineered to loft the valves. Bring $$$$$$$$

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PostPosted: Wed Dec 11, 2019 6:04 pm 
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This rule was written when all of the cars required some lash. Pretty sure the 72 GCR reads the same way. I figure it is merely an oversight and a failure of the CRB to keep up with the modern valve train technology.

I checked a couple today. The best method is to depress the valve ( tell it a sad story), and set the dial indicator to zero, rotate the engine until the valve is full up. Read the value. Simple and fair to all of the valve trains .

We should not reduce the competitiveness of the old engines any more than we already do.IMHO
Thanks for your input .MM

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