Lotus Elan

Are "Top-Hat" shims the correct type?

PostPost by: davidwinegar » Tue Jun 28, 2005 7:04 pm

Thanks Brian, this helps greatly.

Just wonderig if top-hat shims are what are supposed to be in there?
A couple of mine have these types of shims but no one around here has
seen this type and we thought that they were somehow not correct.
What should I be using?

Regards.

David

--- In ***@***.***, "Brian Goodison" <[email protected]>
wrote:
--- In ***@***.***, "Greg Zelazek" <[email protected]>
wrote:
> --- In ***@***.***, "david_c_w" <[email protected]>
wrote:

> > Second question is the shims in my car are very strange looking.
Mine
> > are smaller diamter than the hole where they fit and are quite
> You might have a Cosworth setup, due to, perhaps, relatively radical

I think QED,Burtons,Cosworth and some others have "top hat" shims and
are as the name implies(top hat in shape) If your shims are just flat
and a smaller diameter so they are loose in the retainer that cant be
right! the T.C. shims are 5/8" diameter.
I have seen thin small diameter ones fitted in a T.C.and I think they
were from a motorcycle...Kawasaki I think.
Brian
64Elan/72Sprint/J.P.S.Europa/Birkin T.C.Seven
davidwinegar
Second Gear
Second Gear
 
Posts: 150
Joined: 23 May 2004

PostPost by: "Brian Goodison" » Tue Jun 28, 2005 8:03 pm

--- In ***@***.***, "david_c_w" <[email protected]> wrote:
Thanks Brian, this helps greatly.

Just wonderig if top-hat shims are what are supposed to be in
there?

A couple of mine have these types of shims but no one around here
has

seen this type and we thought that they were somehow not correct.

David,
I have never used them myself although I have seen them, they are not
used under normal circumstances in a T.C.
As far as I know they are used in racing applications and when the
base circle of the cams have been modified.
Maybe one of the racers can add something.
Brian
64Elan/72Sprint/J.P.S.Europa/Birkin T.C.Seven
"Brian Goodison"
 

PostPost by: "Sean Murray" » Tue Jun 28, 2005 10:30 pm

Brian,

I think you are on the right track. I have had heads with both "disc" and "top hat" shims. Which type are used seems to depend on the cam/valve/valve spring/retainer/spring seat combination. Normally the disc type is retained laterally by sitting in the cup in the valve spring retainer. If a combination is used where the valve stem is level with, or protrudes above the top of the retainer cup, a "top hat" shim is used which sits on the valve stem. The shim is now retained laterally by the cup in its underside . David Bean lists 9 different valve stem lengths, 3 different retainer types, and 4 different thickness spring seats, and 3 different cam follower thicknesses, That's 324 combinations !

Sean Murray (Not really a racer !)
----- Original Message -----
From: Brian Goodison
To: ***@***.***
Sent: Tuesday, June 28, 2005 9:02 PM
Subject: [LotusElan.net] Re: Are "Top-Hat" shims the correct type?


--- In ***@***.***, "david_c_w" <[email protected]> wrote:
Thanks Brian, this helps greatly.

Just wonderig if top-hat shims are what are supposed to be in
there?

A couple of mine have these types of shims but no one around here
has

seen this type and we thought that they were somehow not correct.

David,
I have never used them myself although I have seen them, they are not
used under normal circumstances in a T.C.
As far as I know they are used in racing applications and when the
base circle of the cams have been modified.
Maybe one of the racers can add something.
Brian
64Elan/72Sprint/J.P.S.Europa/Birkin T.C.Seven
"Sean Murray"
 

Total Online:

Users browsing this forum: No registered users and 14 guests