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ISX

Valve Lash Settings

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ISX    58
ISX

So I changed the lash to 8 intake 15 exhaust. It still spools really good but not the jump I was expecting because it was a huge difference when I went from 10/20 to 8/18 so I thought 8/15 would be a big jump again on spoolup but I don't think it changed that much. I am thinking me cleaning the turbo and all the crap off of the turbine shaft must have gave it a big kick. I will say this though, it runs reallllllly smooth now. The power just rolls on perfectly, no points on the throttle that are more powerful than others, even down at lugging speeds. I might go back and set the intakes down to 6 and see what happens.

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guesswho512    2
guesswho512

and historically, you have always set them to .010/.020?

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ISX    58
ISX

and historically, you have always set them to .010/.020?

Yep, I never even thought about making them tighter until I got curious to why JL was running 8/18.

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Terry C    0
Terry C

Just be careful with the tight tolerances.... it just might get expensive real quick.

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ISX    58
ISX

Does two thousands really make that much difference?

At only 1000RPM, each piston hits TDC 16 times a second. It happens so fast that any tiny adjustment with the valves makes a difference.

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Mopar1973Man    3,653
Mopar1973Man

Just be careful with the tight tolerances.... it just might get expensive real quick.

That's my fears... Somewhere down the line there was a reason for the original .010 and .020... I can see shaving a few thousandths off but cutting back to deep I'd start to worry...

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RPM    0
RPM

The exhaust side is where it will help most.

Hmmm, well I guess I will have to try that when I adjust them next spring

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dually    0
dually

Mine are at 10 and 20.I am with Mike on this one.I may change to 8 or 9 and15 to 18 but thats as far as i would feel safe with.

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ISX    58
ISX

Yeah I am going to have to stay on top of them. They get loose most times rather than tighter so being as tight as the service manual allows means I have a lot of room to get loose. Someone had worse mpg running them like this so we will see what I get.

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white01    0
white01

mine are at 10/20...thinkin' whenb the new stix go in i may go to 8/17:thumbup2:

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RPM    0
RPM
I can see going with 8/18 if it makes a difference. Without knowing what the piston to valve clearance is I don't know if I would be comfortable going further. I can see the argument of having a little more space to loosen before they are out of spec, but on the other hand I can see heat expansion.

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white01    0
white01

been awhile but i have been on the 8 and 17 for awhile:thumbup2:

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JOHNFAK    85
JOHNFAK

been awhile but i have been on the 8 and 17 for awhile:thumbup2:

thought I read that unless you run a modified CAM or have altered the clearance with head being shaved etc you pretty much cant have a clearance issue with valve contact ........ :shrug:

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