Author Topic: Cam Shims: Yay or Nay?  (Read 641 times)

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Offline JW113

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Cam Shims: Yay or Nay?
« on: January 22, 2019, 04:41:54 PM »
Any thoughts on ironhead cam shims? I think if you follow the various years of manuals, the cam end play went from like a minimum of .005", to eventually .050", which often did not even need any shims. I've also heard often to not even bother with shims, as too many times they're found all ground up in the bottom of the cam chest during a tear down. Other than perhaps reduce some of the valve train noise (in which an ironhead is surely swimming in), what good do they do?

-JW
2004 FLHRS   1977 FLH Shovelhead  1992 FLSTC
1945 Indian Chief   1978 XL Bobber

Online Burnout

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Re: Cam Shims: Yay or Nay?
« Reply #1 on: January 23, 2019, 01:42:49 PM »
I shim them but only use the thickest shims.

As you know the thin shims get ate up.
No point in using them.
They don't call me Ironhead Rick just because I'm "hard headed"

Offline garyajaz

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Re: Cam Shims: Yay or Nay?
« Reply #2 on: January 31, 2019, 09:15:08 AM »
if I remember correctly Sifton first mentioned to not use shims with their cams.
then Harley put out a bulletin.
like mentioned the thinner shims would tear and hurt things in cam chest area.
I been running shimless since 1976 or so.


Offline JW113

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Re: Cam Shims: Yay or Nay?
« Reply #3 on: January 31, 2019, 02:58:44 PM »
Yes, the stock P cam set in my '78 are also running sans shims. Other than a lot of valve train noise, no obvious side effects. I have a set of Andrews R5 cams that I am going to install. A little less noise would be nice, but not if it means a hit to reliability. Guess I'll see what they mic out for end play, and if on the long side of spec, maybe a thick shim to dial it in a little. Else, just go with it.

What do you guys like to lash them to? Zero? Eight thou?

-JW
2004 FLHRS   1977 FLH Shovelhead  1992 FLSTC
1945 Indian Chief   1978 XL Bobber

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Re: Cam Shims: Yay or Nay?
« Reply #4 on: January 31, 2019, 04:31:12 PM »
I set them at zero cold, they lash themselves when you get some heat in it.

Cold means stone cold in the morning, any heat in the motor will screw this up.
If you set them at zero hot the valves will not close when cold.
They don't call me Ironhead Rick just because I'm "hard headed"

Offline JW113

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Re: Cam Shims: Yay or Nay?
« Reply #5 on: February 01, 2019, 01:05:41 PM »
The reason I ask is that a guy on another forum was doing some dyno tuning, and found that lashing the tappets to 8 thou (1/4 turn back) yielded noticeably more torque, like 5-10 ft/lbs more. Never heard/seen that before, but he had the charts to show it.

-JW
2004 FLHRS   1977 FLH Shovelhead  1992 FLSTC
1945 Indian Chief   1978 XL Bobber

Offline turboprop

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Re: Cam Shims: Yay or Nay?
« Reply #6 on: February 01, 2019, 03:12:47 PM »
The reason I ask is that a guy on another forum was doing some dyno tuning, and found that lashing the tappets to 8 thou (1/4 turn back) yielded noticeably more torque, like 5-10 ft/lbs more. Never heard/seen that before, but he had the charts to show it.

-JW

Increasing the valve lash is an old school way of making small adjustments to valve timing.
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Online Burnout

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Re: Cam Shims: Yay or Nay?
« Reply #7 on: February 01, 2019, 04:38:45 PM »
It is a clue that you have chosen a cam that has too much duration.

I believe it is not a good practice as it defeats the quieting ramps on the cam and hammers the valve train.
They don't call me Ironhead Rick just because I'm "hard headed"

Offline JW113

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Re: Cam Shims: Yay or Nay?
« Reply #8 on: February 02, 2019, 02:17:49 PM »
This article was over in the jockey journal forum. And per this dude's dyno charts, even the STOCK P cams picked up some torque with the valves lashed .008". Not just down low, all across the board. I agree, running with lash seems like it would be on the noisy side. I'm wondering if what is happening is that leaving some last when cold, after the motor gets hot the push rods grow and takes up the last. Perhaps setting to zero lash cold meals preloading the valves when it gets hot? I've never actually checked the pushrods on a hot motor to see if they're still loose, or have some preload on them.

-JW
2004 FLHRS   1977 FLH Shovelhead  1992 FLSTC
1945 Indian Chief   1978 XL Bobber

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Re: Cam Shims: Yay or Nay?
« Reply #9 on: February 02, 2019, 08:13:22 PM »
The cylinders grow more than the pushrods, the push rods don't get hot.
They don't call me Ironhead Rick just because I'm "hard headed"

Offline garyajaz

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Re: Cam Shims: Yay or Nay?
« Reply #10 on: February 04, 2019, 10:58:18 AM »
have never measured or counted flats.
always have used the two finger turn method.
just free on the intake. even more free (lol) on the exhaust side.

Offline saltcaveminer

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Re: Cam Shims: Yay or Nay?
« Reply #11 on: February 26, 2019, 03:56:12 PM »
I agree with Gary. PS do them cold. Salty