[Shotimes] valve clearance questions

[Ian Fisher]

My understanding of how to check valve lash is:

Check clearance between the lobe and add difference to
the size of the shim that's already in there. Order or
swap in proper shim to get it into spec.

To make things easier, I just popped the shims out of
the buckets and wrote down what I already have. I
installed the +20 cam lashcaps and reassembled with
the new cams in place (finger tight on the cam
journals for now since I'm not checking clearances
yet..)

Question 1: Should I also mic the shims and record
what the measured size is? If the shims are worn, I
assume they are no longer the size that is stamped on
the bottom of the shim?

Question 2: I noticed that some of the heavier shims
like the 2600's tend to spin in the buckets and the
thinner ones don't. Just wondering if anyone knew why.

Question 3: What unit of measurement are the shims in?
I guess if I checked the Helms or thought for a
second, I would be able to figure it out (excuse
alert: I am on a heavy dose of decongestants and I'm
ready to fall over and sleep at any second)

Question 4: I stripped a set of 93 ATX heads for the
shims yesterday. I noticed that most of the shims were
in the 2400-2500 range. My 90 3.0 heads that I'll be
using had 2475-2600 installed. Do the 3.0 cams
typically use thicker shims or am I looking for a
corelation of some sorts that doesn't exsist? Just
curious...

Question 5: If I'm swapping 3.0 cams for +20's can one
reasonably expect that I'll require thinner shims than
what's in there? The valve seats were also machined
when the heads were rebuilt with new guides so I
assume that this would move the valve stem up
(effectively decreasing the shim to lobe gap?).

I'm not looking for anyone to rub a crystal ball and
tell me what shims I need. I'll figure it out when I
check the clearances using the proper tools. Just
wondering what I should expect to find..

thanks!
Ian



		
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