Cold lash after 500 miles, yikes!

[tenxal]

Good Lord. This is not that difficult.....

[MadBill]

There used to be (still is?) a tool or tools available that positioned a dial indicator on the valve end of the rocker. I've still got the mostly-finished home version I started on 40 years ago but never finished.

I also recall reading of an impromptu contest at the SuperFlow conference one year, in which a number of experts performed their most meticulous possible lash routine on an engine, which was then checked with such a tool. AIR, results varied up to 0.005"...

As pointed out earlier, no one to my knowledge has reported power effects from minor inadvertent variations.

[Alkyfool]

In mid 70's, I stamped a adjustment procedure I think found in the Chev factory performance manual (MOPAR too) on a piece of sheet aluminum and pop riveted it to the firewall where you rotate every 90' through the firing order and set one IN and on EX .

So at #1 TDC firing, you set IN 2 and EX 8. Rotate 90' to #8 firing and then set IN 1 and EX 4. Continue through the firing order with this same pattern.

How would this method stand up to EO IC (which is the method I use most today and engraved it on my lash tools a long time ago)?

[Stan Weiss]

This a based on an S96 file of a Chevy 30 30 that someone shared with me. How far off would the lash be if set @ TDC?

Stan

Code: Select all

       I  N  T  A  K  E
Rocker Arm Ratio = 1.500         Valve Lash = 0.03000        Valve Angle = 23.0

VALVE     Lift      Opens   Closes  Duration
                 Deg BTDC  Deg ABDC             Area
         0.00000    39.41 | 107.91 | 327.31 |  38.97
         0.00050    38.34 | 105.99 | 324.33 |  38.97
         0.00100    37.32 | 104.24 | 321.56 |  38.97
         0.00600    30.24 |  91.66 | 301.91 |  38.93
         0.01000    26.63 |  85.42 | 292.05 |  38.89
         0.02000    20.52 |  76.85 | 277.37 |  38.75
         0.04000    12.37 |  66.90 | 259.27 |  38.45
         0.05000     9.08 |  63.12 | 252.19 |  38.36
         0.10000    -3.83 |  48.62 | 224.80 |  37.21
         0.15000   -14.29 |  37.63 | 203.35 |  35.92
         0.20000   -24.23 |  27.62 | 183.39 |  34.14
         0.25000   -34.41 |  17.44 | 163.03 |  31.86
         0.30000   -45.46 |   6.41 | 140.95 |  28.50
         0.35000   -58.05 |  -6.17 | 115.78 |  24.53
         0.40000   -73.80 | -21.88 |  84.32 |  18.46
         0.45000  -101.00 | -48.82 |  30.18 |   6.83
CAM
         0.00050   142.91 | 248.02 | 570.93 |  30.34
         0.00100   140.22 | 247.04 | 567.26 |  30.34
         0.00600   112.81 | 181.17 | 473.98 |  30.21
         0.01000    90.58 | 160.43 | 431.01 |  30.03
         0.02000    39.41 | 107.91 | 327.31 |  29.26
         0.04000    16.09 |  71.28 | 267.37 |  28.44
         0.05000    10.68 |  64.95 | 255.63 |  28.11
         0.10000    -8.13 |  43.99 | 215.86 |  26.66
         0.15000   -23.24 |  28.62 | 185.38 |  24.60
         0.20000   -38.69 |  13.17 | 154.47 |  22.10
         0.25000   -56.69 |  -4.80 | 118.51 |  18.02
         0.30000   -81.89 | -30.01 |  68.10 |  10.79

I know most cams are not like the Chevy 30 30. But with the intake @ 117 ICL there is around .006" lifter raise ATDC which with a 1.5:1 rocker arm ratio is .009" extra lash. Look at how much seat-to-seat duration has change and how much cam area is lost.

Stan

Code: Select all

       I  N  T  A  K  E
Rocker Arm Ratio = 1.500         Valve Lash = 0.03900        Valve Angle = 23.0

VALVE     Lift      Opens   Closes  Duration
                 Deg BTDC  Deg ABDC             Area
         0.00000    27.44 |  86.68 | 294.12 |  37.57
         0.00600    23.24 |  80.52 | 283.76 |  37.55
         0.01000    21.01 |  77.53 | 278.54 |  37.54
         0.02000    16.49 |  71.78 | 268.27 |  37.44
         0.04000     9.40 |  63.48 | 252.88 |  37.22
         0.05000     6.39 |  60.06 | 246.45 |  37.03
         0.10000    -5.80 |  46.49 | 220.69 |  36.00
         0.15000   -16.09 |  35.81 | 199.71 |  34.70
         0.20000   -26.03 |  25.82 | 179.79 |  32.91
         0.25000   -36.32 |  15.53 | 159.21 |  30.62
         0.30000   -47.59 |   4.28 | 136.70 |  27.26
         0.35000   -60.58 |  -8.68 | 110.73 |  23.32
         0.40000   -77.21 | -25.32 |  77.47 |  16.49

[CamKing]

When you do it the right way, instead of all the incorrect alternative methods. It is quick easy and accurate and pain free. (And your lifters live too.)

I can't believe my lifters survive cause I set them at TDC.

Well,.. just maybe my cams aren't "racey" enough !!

Randy

With 95+% of the cams out there, setting the lash at TDC is perfectly fine. It takes a pretty long duration cam, to still be on the lash ramp, at TDC.

I just looked at a Pro-Stock exhaust lobe I designed. It's 310@.050" with .530" Lobe Lift. If it was on a 122 Exhaust centerline, it would be on the base circle at TDC, but only by 1.25 degrees. Not a lot of guys running over 310@.050", or wider then a 122 ECL.

[Belgian1979]

When you do it the right way, instead of all the incorrect alternative methods. It is quick easy and accurate and pain free. (And your lifters live too.)

I can't believe my lifters survive cause I set them at TDC.

Well,.. just maybe my cams aren't "racey" enough !!

Randy

With 95+% of the cams out there, setting the lash at TDC is perfectly fine. It takes a pretty long duration cam, to still be on the lash ramp, at TDC.

I just looked at a Pro-Stock exhaust lobe I designed. It's 310@.050" with .530" Lobe Lift. If it was on a 122 Exhaust centerline, it would be on the base circle at TDC, but only by 1.25 degrees. Not a lot of guys running over 310@.050", or wider then a 122 ECL.

[6.50camaro]

In mid 70's, I stamped a adjustment procedure I think found in the Chev factory performance manual (MOPAR too) on a piece of sheet aluminum and pop riveted it to the firewall where you rotate every 90' through the firing order and set one IN and on EX .

So at #1 TDC firing, you set IN 2 and EX 8. Rotate 90' to #8 firing and then set IN 1 and EX 4. Continue through the firing order with this same pattern.

How would this method stand up to EO IC (which is the method I use most today and engraved it on my lash tools a long time ago)?

I have used the set #1 @tdc firing check intake #2, exhaust#8 method for years .I found it in Speedway Motors catalog in one of Speedy Bill's tech tips they had it there for years . If you check you are setting #2 intake when#2 exhaust is on the clearance ramp just starting to open.#8 intake has just seated or is just about to ,so you set #8 exhaust lash .It maybe a few degrees off "optimum" of EO IC but not that far . You rotate the engine over twice stopping ever 90° its quick simple you dont miss the "spot" and have to rotate around again and think was that with the valve just opening or just closing. I make a chart X out the valve I just adjusted that way if interrupted I don't lose my place. Been doing it 25 years this way never what a problem. Dan

[fdicrasto]

Hey, I'm not going to be the dog that can't be taught new tricks. I am going to stop being anal about valve adjustment and go with what CamKing has posted.

[F-BIRD'88]

Do it the right way. EO. IC. You'll never go wrong
And those pesky roller lifters will be happy.

[Bishop540]

Looks like there is about .005 or so difference between EOIC and TDC (more lash at TDC). I just checked both. I remember when I was degreeing the cam I would see the dial indicator move around on the basecircle of the cam. I dont remember how much but I bet it was at least .005 or more. Is that about normal for a solid roller?

I took the car to wash it the other day, about 6 miles or less. All the lash seems to still be at .020 at EOIC, like I set it the other day. Maybe thats not enough miles to determine an issue with lash but its too tight for this cam. I guess it makes it a slightly "bigger" cam with tighter lash. But I didn't like the way it idled or ran, unless I had a few too tight. Either way I'm gonna open them to .025 cold at EOIC.

[Bishop540]

Ok, so maaaybe there were a few that were a bit snug on lash but not too much.....

[Stan Weiss]

Looks like there is about .005 or so difference between EOIC and TDC (more lash at TDC). I just checked both. I remember when I was degreeing the cam I would see the dial indicator move around on the basecircle of the cam. I dont remember how much but I bet it was at least .005 or more. Is that about normal for a solid roller?

I took the car to wash it the other day, about 6 miles or less. All the lash seems to still be at .020 at EOIC, like I set it the other day. Maybe thats not enough miles to determine an issue with lash but its too tight for this cam. I guess it makes it a slightly "bigger" cam with tighter lash. But I didn't like the way it idled or ran, unless I had a few too tight. Either way I'm gonna open them to .025 cold at EOIC.

No you should not be seeing that on the base circle.

Stan

[gmrocket]

There used to be (still is?) a tool or tools available that positioned a dial indicator on the valve end of the rocker. I've still got the mostly-finished home version I started on 40 years ago but never finished.

I also recall reading of an impromptu contest at the SuperFlow conference one year, in which a number of experts performed their most meticulous possible lash routine on an engine, which was then checked with such a tool. AIR, results varied up to 0.005"...

As pointed out earlier, no one to my knowledge has reported power effects from minor inadvertent variations.

Yup, why be so anal with one end of it when we are using an antique feeler gauge and going by drag feel on the other end?

My adjuster is at the pushrod cup on this deal, not the rocker stud, so there is no lag from rocker to pivot point.

[Bishop540]

An expert reminded me that I need a bit more intake lash, since I have 1.8's (.030/1.7 = .0176 x 1.8 =.0318). So I cold lashed the intake to .028 and the exhaust to .026. Mr Harold's range was .020 to .034 hot.

My final method was: just when the exhaust started to open & just when the intake closed. And that's how I am going to check them down the road after a couple cruise nights. I would like to check them hot in the near future too. Thanks to all!

[gmrocket]

Looks like there is about .005 or so difference between EOIC and TDC (more lash at TDC). I just checked both. I remember when I was degreeing the cam I would see the dial indicator move around on the basecircle of the cam. I dont remember how much but I bet it was at least .005 or more. Is that about normal for a solid roller?

I took the car to wash it the other day, about 6 miles or less. All the lash seems to still be at .020 at EOIC, like I set it the other day. Maybe thats not enough miles to determine an issue with lash but its too tight for this cam. I guess it makes it a slightly "bigger" cam with tighter lash. But I didn't like the way it idled or ran, unless I had a few too tight. Either way I'm gonna open them to .025 cold at EOIC.

No you should not be seeing that on the base circle.

Stan

Jeeeziz krist..if your seeing .005" movement on the base circle you have problems..either you or the cam.

Did you mean .0005" ?

Your cam has 255/263 at .050" on a 107....almost identical to the one I just did.

You should have no problems doing lash at tdc . Unless you have some wierd way off adv or retard setting.