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Discussion Starter #1
While I lay in wait for my valve adjustment tool to come in the mail, I got to thinking about what changes I could make with the valve lash and how they would affect how the valve reacts to the cam profile. Of course as I was thinking this I remembered you had a Valve Lash Tuning portion in your Engine Package I article. When I read it, I got a slightly different answer than what I had been thinking so I thought I'd ask for clarification.

Mike, in your article you state valve lash is "how long the rocker arm sits on the cam lobe". With that explanation I will assume that increasing valve lash means adjusting the lifter closer to the cam lobe. So with that you say:

Increasing lash will increase cylinder pressure at low to midrange RPM's, close the intake valve sooner, and reduce cam overlap & total cam duration. The effect is slightly similar to ADVANCING the cam gear . Too much lash increases wear on all components, lowers maximum RPM, and increases the possibility of breakage.

Now I understand that running a tighter adjustment will increase wear on the lifter as the lobe will sit heavier on the lifter when in contact. With that this is what I don't understand. I would think with a tighter adjustment, you would have increased cam duration (and possibly lift?) due to the lobe being in closer contact to the lifter. This would to me would seem better for high RPM breathing and reduce cylinder pressure in the low RPMs.

However you explain the increased duration and reduced low RPM cylinder pressure comes from reducing the lash which I am taking to mean as a looser adjustment where the lobe is further away from the lifter. That's what I don't understand, why it works that way and not the way I think it does. Any clarifications?
 

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if you tighten the lash beyond the recommended Honda specs and the engine picks up power, then that means you have undercammed your engine for the dynamic cr you have with your current static cr. the car is telling you it likes a little more duration and/or lift...more overlap...less lsa.

If it doesn't gain anything , then your cam is just right with stock valve lash and you don't have to get bigger cams for the package you have.

This is an old domestic hot rodder's trick to see if you should upgrade cams or not. Be prepared to advance the exhaust cam gear so she'll idle if you get a lumpier idle with a tighter lash.
 

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Discussion Starter #4
I'm too poor to do a dyno test for something like that haha. I've been saving for my dyno time with the HyTech setup and cam gear + V-AFC tuning. If I can scrap some spare time during those runs without it adding anothing hour to the session I will try it but I doubt I can do a valve adjustment that fast.
 

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you have to do the adjustment with the engine dead cold anyways...

I can tell you that the Hytech will like more intake cam advance. The more cylinder pressure you can build up the better, especially since you still are running on stock CR.

you can always run a tighter valve lash before you go to the dyno or at the very least, set it at the tightest stock spec on the intake cam.
 

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Discussion Starter #6
Oh yeah the engine does have to be cold haha, not like I was thinking of doing it anyway. I am planning to do a valve adjustment just before dynoing and I was going to set it maybe a point or two tighter to get slightly more duration on the cams.
 

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i got a quick question for MD where the hell did you learn all your stuff , you litterally know everything!
 

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ah grasshopper... there is a wealth of knowledge at your fingertips. the true question is where should one start looking for it?
 
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