[Saloon-lovers] Machining cylinder head cam followers

The loud tapping noise in the head of my engine turned out to be a loose
guide so a rebuild is in progress including new valves, guides and cam
followers. The followers (or worn guides) are the only makers of noise
if your valves are adjusted to spec.

Whenever I have rebuilt an XK cylinder head I have always had to use a
few shims sizes that are less than the .085 standard starting thickness.
In addition, the new cam followers I bought are 10 thou thicker than the
old ones.

Therefore I have a plan I wanted your advice on.

  1. I will take the cam followers to a machine shop and get them to
    machine 20 thou off the inside part that contacts the shim. This means
    that the part that contacts the valve shimm is only 10 thou thinner than
    the worn ones I took out.

  2. I will get a machine shop to take 10 thou off the valve stem. This
    should not be so much that the shim has risk of pushing against the
    collett instead of the stem when the shim wears against the stem due to
    high mileage.

The result is that whereas I was using shims that were around 70 thou, I
will now be in the 90 thou range of which there are plenty in the
bucket. If I do nothing I’ll have to make 60 thou shims

Does anyone have any advice on this??

Dennis 69 OTS

dkmacm@bc.sympatico.ca wrote:

The loud tapping noise in the head of my engine turned out to be a loose
guide so a rebuild is in progress including new valves, guides and cam
followers.

Hello Dennis:

 When you say "loose guide" do you mean valve guide or tappet guide ? If 

it was a loose valve guide, was it loose in the head, or was the valve stem
to guide bore a loose fit ? You can probably guess why I’m asking.
The undersized tappets that I have used have been skimmed on the top,
not on the inside of the tappet. I don’t think you want to reduce the raised
portion of the inside because you do not want the tappet to hit the spring
retainer. The thinner shims may sit below the level of the retainer and the
raised portion prevents operating the valves by the spring retainer. It is
also easier to have the tops skimmed and it accomplishes the goal. I am not
a machinist, but I think the procedure uses a precision grinder and a
magnetic table. You can also buy them from GTJ and XKS in 0.010, 0.020 up to
0.050 for about $40 each. Your other option would be to use reground
camshafts which generally have 0.050 ground off the base circle which may
bring you back into the proper shim range with the standard tappets. I also
have the little book you are referring to, it does not say much, but it does
say to loosen up your valve clearances for racing. I will try to find it.
Good luck.

Paul Saltwick
3.8 S TypeSubject: [Saloon-lovers] Machining cylinder head cam followers

If it’s a loose tappet guide, there is a “bolt on” piece that keeps the
guide from riding up and getting hit. I had them put in my '64 MK10 after I
replaced the thermostat. With the old thermostat not closing , the engine
didn’t get warm enough for the metal to contract and therefore not warm
enough for the guide to get loose (wasn’t warm enough to get any heat
either). It cost me around $40-60 which seemed like a good deal since I had
just had the head rebuilt. During the rebuild, the tappet guides were the
only thing not replaced.

Bob Powell
'64 MK10
'66 MK10
Senior Programmer
Brandywine Electronics, LTD
34 Blevins Dr., Suite 10
New Castle, DE 19720
800.924.9992 ext 106
302.324.9992 ext 106
302.324.8611 fax
www.bel.com-----Original Message-----
From: owner-saloons@jag-lovers.org
[mailto:owner-saloons@jag-lovers.org]On Behalf Of dkmacm@bc.sympatico.ca
Sent: Thursday, March 17, 1994 11:02 PM
To: saloons@jag-lovers.org
Subject: [Saloon-lovers] Machining cylinder head cam followers

The loud tapping noise in the head of my engine turned out to be a loose
guide so a rebuild is in progress including new valves, guides and cam
followers. The followers (or worn guides) are the only makers of noise
if your valves are adjusted to spec.

Whenever I have rebuilt an XK cylinder head I have always had to use a
few shims sizes that are less than the .085 standard starting thickness.
In addition, the new cam followers I bought are 10 thou thicker than the
old ones.

Therefore I have a plan I wanted your advice on.

  1. I will take the cam followers to a machine shop and get them to
    machine 20 thou off the inside part that contacts the shim. This means
    that the part that contacts the valve shimm is only 10 thou thinner than
    the worn ones I took out.

  2. I will get a machine shop to take 10 thou off the valve stem. This
    should not be so much that the shim has risk of pushing against the
    collett instead of the stem when the shim wears against the stem due to
    high mileage.

The result is that whereas I was using shims that were around 70 thou, I
will now be in the 90 thou range of which there are plenty in the
bucket. If I do nothing I’ll have to make 60 thou shims

Does anyone have any advice on this??

Dennis 69 OTS