Lotus Elan

Cams

PostPost by: johnjacobs » Thu Jun 16, 2005 5:42 pm

Maybe this is a Dumb question, but just wanted to check:

Are both cams the same in the Twink? My brother is rebuilding my UK
Elan+2, and didnt label which was where.
Does it matter where they go back in to?

TIA,
John J
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johnjacobs
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PostPost by: "Brian Goodison" » Thu Jun 16, 2005 5:57 pm

--- In ***@***.***, ***@***.***e:
Maybe this is a Dumb question, but just wanted to check:

Are both cams the same in the Twink? My brother is rebuilding my UK
Elan+2, and didnt label which was where.
Does it matter where they go back in to?

In a standard engine both cams are the same but swaping them over
will
effect the valve clearences, if you are not replacing the cam
bearings
it would be better to refit in the original position.
Brian.
64Elan/72Sprint/J.P.S.Europa/BirkinT.C.Seven
"Brian Goodison"
 

PostPost by: "Martin Stuart" » Thu Jun 16, 2005 6:46 pm

Seconding Brian's response: the cams are the same, but if you are re-using cam bearings and tappets, they need to go back in the original banks, with the indivisual tappets in their original positions.

Even then, you need to check valve clearances and adjust shimming as necessary, because at the very least you will have lapped in the valves, disturbed spting caps and retainers etc. It shouldn't make a big difference, but it can (and in any case it is all too easy to get components accidentally mixed up and ruin the clearances).

To be honest, I'd be replacing the cam bearings as a matter of course if I were rebuiilding the engine, though, along with new valve springs and - if there is the slightest sign of wear or pitting - new tappets. Then there are the valve guides, of course, which tend to wear badly in the Twin Cam and are almost certainly going to need replacement in any engine that needs a rebuild, which in turn dictates new valves...it all gets very expensive very quickly, unfortunately, if you are going to do the job right!

Whilst not wishing to say anything against your brother, if he is being kind enough to rebuild your engine for you, the Twin Cam is quite a sensitive engine to rebuild - the thought of it being put back together by someone who forgets to label parts when he strips it down is just a leeeetle worrying! Are you sure you wouldn't rather send it to QED? ;-)

Martin
----- Original Message -----
From: ***@***.***
To: ***@***.***
Sent: Thursday, June 16, 2005 6:42 PM
Subject: [LotusElan.net] Cams


Maybe this is a Dumb question, but just wanted to check:

Are both cams the same in the Twink? My brother is rebuilding my UK
Elan+2, and didnt label which was where.
Does it matter where they go back in to?

TIA,
John J
"Martin Stuart"
 

PostPost by: "Brian Goodison" » Thu Jun 16, 2005 7:10 pm

--- In ***@***.***, ***@***.***e:

Are both cams the same in the Twink?

Oh, fogot to say, although the cams are the same the sprockets are
NOT
marked the same and need to be on correct cam to maintain timing mark
alignment.
Brian.
64Elan/72Sprint/J.P.S.Europa/Birkin T.C.Seven
"Brian Goodison"
 

PostPost by: "Tim Engel" » Thu Jun 16, 2005 7:27 pm

John,

The OEM cams are the same in Elans (Europa TC's have a longer intake cam to
drive a pulley off the back of the engine). However, out of respect for
wear patterns, the tappets should all go back in the same bores and the
cams in their original locations. In other words, all the surfaces that
wore in together should remain together.

Have the pulleys been removed from the cams. If not, the markings and
orientation of the pulleys will indicate which side they were on.

Good luck,
Tim Engel
Lotus Owners Oftha North



From: <***@***.***>
Are both cams the same in the Twink? My
brother is rebuilding my UK Elan+2, and
didnt label which was where. Does it
matter where they go back in to?
"Tim Engel"
 

PostPost by: john.p.clegg » Thu Jun 16, 2005 10:26 pm

John
Just to be on the safe side,the cams may not be the same profile,some prefer more lift on the inlets than on the exhaust(bigger diameter valve heads),the best bet is to measure the lift and if a difference exists the higher lift as said on the inlet....

John


***@***.***e:
Maybe this is a Dumb question, but just wanted to check:

Are both cams the same in the Twink? My brother is rebuilding my UK
Elan+2, and didnt label which was where.
Does it matter where they go back in to?

TIA,
John J
User avatar
john.p.clegg
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Posts: 5690
Joined: 21 Sep 2003
Location: Manchester

PostPost by: johnjacobs » Fri Jun 17, 2005 4:30 pm

Have the pulleys been removed from the cams. If not, the markings and
orientation of the pulleys will indicate which side they were on.

The pulleys havent been removed - how do the markings indicate which side
the
cam goes back on?

Many Thanks,

John J.
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johnjacobs
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Posts: 17
Joined: 03 Aug 2004

PostPost by: "Brian Goodison" » Fri Jun 17, 2005 4:55 pm

--- In ***@***.***, ***@***.***e:
> Have the pulleys been removed from the cams. If not, the
markings and

The pulleys havent been removed - how do the markings indicate which
side
the
cam goes back on?

The inlet uses a standard jackshaft sprocket (cam sprocket in an
Xflow)
and will probably have no marking but the exh sprocket should be
etched with "EXH"
Brian.
64Elan/72Sprint/J.P.S.Europa/Birkin T.C.Seven
"Brian Goodison"
 

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