Lashing valves

[2quick]

Hi guys, Quick question. I’m in the process of lashing my valves on my solid roller and I always use the EOIC method. I recently read somewhere that when the exhaust valve just begins to open you should adjust the intake but when I do this I actually get a looser lash setting as the exhaust valve goes to full open. So my question is do I set the lash just as the Exhaust valve starts to open or do I adjust the valve at the point on the cam that I see the most Lash. seems to me like it’s farther down on the bass circle of the cam. There seems to be about a .002 difference on the intake Between a just starts to open and a fully open exhaust valve.

Combo in my signature.

 

[diesel_lv]

 

[2quick]

This is not a stock cam.
[email protected] .645 lift
And I can bump the starter with a button so EOIC is better for me.

 

[diesel_lv]

This is not a stock cam.
[email protected] .645 lift
And I can bump the starter with a button so EOIC is better for me.

The Mopar chart puts each cam lobe on the base of the lobe circle. That said, when I adjusted mine, I rotate engine w a breaker bar, more accurate than a starter bump, and rotate until each lobe was at the lowest lift on the base circle.

 

[1 Wild R/T]

The base circle shouldn't have any dips.... Which what you describe sounds like a dip... In theory the valve needs the lash to assure the valve closes fully so heat can transfer from the valve to the seat.... But then again racers tweak the lash to slightly alter duration so you have room to play with and I don't think .002 is critical... The EOIC is just that, at the point of the exhaust lash being taken away & the valve moving but before it crests the lobe you set the intake... And as the Intake is closing but before it hits the base circle you adjust the exhaust...

Again, .002 won't make or break ya..

 

[2quick]

I just checked again. When using EO/IC method on a cold engine, With the exhaust valve just starting to open (about .100 open) I then set the Intake valve for that cylinder. At that point I’m at a tight .010 lash. My engine grows .006 so that puts me at .016 hot! But if I rotate the engine so the exhaust valve is all the way open (.645 open) the intake lash at that point grows to .13 Cold, adding .006 when it warm up gives me .019 hot. So what’s correct .010 or .013? I know .003 is probably not a big deal but sometimes I like to lash a bit tighter to quite it down a bit so I run .008 cold. But is it’s .008 or .005????

I understand there are other ways of doing this but this method is what is easier for me and my setup.

 

[dvw]

I'd go for the maximum clearance spot. Your looking for a consistent number that you can repeat every time. The actual clearance isn't as important as knowing if it's changing. Performance will dictate the actual number. Tighter is easier on the valvetrain. But .003" isn't enough to beat anything up. Keep a lash logbook. Every time the lash is checked if a particular valve changes I want to know. Has it been changing in the past? Say the #3 EXH is .002" looser (or tighter) 3 checks in a row. There is an issue. When they're correct mine never shows any valve moving more than .001" (tight or loose) over 6 checks or more.
Doug

 

[2quick]

I'd go for the maximum clearance spot. Your looking for a consistent number that you can repeat every time. The actual clearance isn't as important as knowing if it's changing. Performance will dictate the actual number. Tighter is easier on the valvetrain. But .003" isn't enough to beat anything up. Keep a lash logbook. Every time the lash is checked if a particular valve changes I want to know. Has it been changing in the past? Say the #3 EXH is .002" looser (or tighter) 3 checks in a row. There is an issue. When they're correct mine never shows any valve moving more than .001" (tight or loose) over 6 checks or more.
Doug

That's what I am thinking, Set at the maximum clearance spot on the cam. I had a couple that were a bit wonky. #1 Intake was tight at .005 Cold/.011 Hot and #5 exhaust was .014cold/.020 Hot, but everything was set at .008 Cold/.014 Hot. This all started cause I'm chasing down a weird consistent lean spike on my datalogger that looks like a miss and has my AFR swinging 2 ratio points in both directions. Makes it impossible to tune. I went through the entire ignition system and thought I should check the valves to see it anything jumped out while I had it apart. I lash tight cause my valve train is really noisy and on the street with long (not so loud mufflers) sometimes it drives me nuts. I think it would go faster though if I opened it up to .020 hot though. Currently kinda a pig on the 60' at 1.56

 

[dvw]

I never set mine hot. While checking them hot the exhaust lash will actually start to change by the time you get to the second side. And it only takes me 15 minutes start to finish.
Doug

 

[2quick]

I would like to hear from some of the engine builders out there as to why I'm seeing an increase in intake lash as the exhaust valve gets opened further and (In my situation) exactly where in the exhaust lift cycle I should be setting the intake lash?

 

[dvw]

Obviously the ramp tapers off very slowly. Unless the cam flexes that far which to me doesn't sound likely.
Doug

 

[PRHeads]

The intake lash grows when the ex goes from barely open to full open because the cam deflects from the added spring force of the exhaust being fully open.
The load on the cam is the spring force x the rocker ratio.
So if you had 650lbs of force from the spring and a 1.6RR, the load at the cam is 1040lbs.

You could test for this by removing the other 3 pushrods that are between the two cam bearings for the lobe you’re working on, and check the lobe runout on the base circle and see how it compares to the runout with the other three pushrods/rockers installed.

One of the benefits of using cams with larger barrel diameters(like what you’d get with a 55-60mm cam) is the reduced deflection caused by high spring loads.

Don’t over think the lash point.

If you want to try a tighter lash setting, use the normal lash point and a thinner feeler gauge.

 

[PRHeads]

As for the lash and it’s possibility of relating to your running condition, I’d be more inclined to set the lash on the loose end of the range to be sure you’re not running the motor on the clearance ramps.

If that doesn’t improve things, IMO that would rule out the lash being a contributing factor to the problem you’re having.

 

[2quick]

Makes some sense now.

 

[440 Charger]

This is not a stock cam.
[email protected] .645 lift
And I can bump the starter with a button so EOIC is better for me.

Interesting you went with a low cam lobe?

 

[dvw]

I'm curious as to why some disagree with my post #9? Is it the fact I do them cold? Or the fact that they change quickly hot? Lash changes a fair amount hot to cold depending on material and temp. Once you know what that amount of change is. you're set. My racecar gets the valves lashed every 20-25 passes. The current car has over 750 passes. My bet is I lash valves way more often than the average enthusiast.
Doug

 

[SuperRatBastid]

I'm curious as to why some disagree with my post #9? Is it the fact I do them cold? Or the fact that they change quickly hot? Lash changes a fair amount hot to cold depending on material and temp. Once you know what that amount of change is. you're set. My racecar gets the valves lashed every 20-25 passes. The current car has over 750 passes. My bet is I lash valves way more often than the average enthusiast.
Doug

I don’t know anyone who lashes valves hot or who lashes their valves that much.

 

[2quick]

I'm curious as to why some disagree with my post #9? Is it the fact I do them cold? Or the fact that they change quickly hot? Lash changes a fair amount hot to cold depending on material and temp. Once you know what that amount of change is. you're set. My racecar gets the valves lashed every 20-25 passes. The current car has over 750 passes. My bet is I lash valves way more often than the average enthusiast.
Doug

Actually I think I hit dislike button by accident, I just noticed my name next to it. But yes I lash cold also. Sorry for that!

 

[2quick]

Interesting you went with a low cam lobe?

Speced for me by PRHeads!

 

[2quick]

Follow up. Got them lashed to .014 cold just as exhaust valve starts to crack open and almost when intake is closed, so the least amount of cam deflection possible when adjust the pair. Had a bunch of other things to figure out that ultimately wound up being a Firmware update on my FAST ECU that enabled (Fuel Pump Compensation) that Fouled 2 sets plugs and 2 O2 sensors before FAST helped me figure it out. After all that mess which I thought was a miss so pretty much rewired car and checked or replaces every ignition component on the thing. It now runs and sounds much much better and the CAM seems much quieter also. I can hear the valves pop open but the clicking is much less now. Happy days!! Butt dyno says the car feels much faster. With any luck hope to crush my best 10.86 run next time out.