Lotus Elan

Cam follower clearance.

PostPost by: vincereynard » Mon Nov 06, 2017 6:31 pm

Can anyone recommend a machine shop around the Bucks area who could measure and advise on
the clearance between follower and sleeve.

Toad has a faint tick on No 2 cylinder. It can clearly be heard by holding a plastic tube against the trumpet in carb balancing style. Suck suck on 1 / 3 / 4 , suck tick on No2. The clearances have been checked and are all OK. A camera thing down the plug hole shows no indication of valve / piston contact. Next (most likely?) situation is a worn cam follower.

Are the sleeves shrunk in place? Do they need matching to the followers?
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PostPost by: rgh0 » Mon Nov 06, 2017 8:46 pm

The head is warmed and the sleeve is chilled and then fitted in place. The sleeve is then finish honed to the correct diameter as specified in the manual to match the new cam follower.

When measuring up the sleeve and follower you need to measure top, middle and bottom as the follower wears in a barrel shape and the sleeve in an hour glass shape.

cheers
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PostPost by: HAIRY » Tue Nov 07, 2017 5:28 pm

My Twin Cam had a ticking noise from the top end. It turned out to be the Cam shaft shells moving in their housing.
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PostPost by: vincereynard » Tue Nov 07, 2017 5:37 pm

HAIRY wrote:My Twin Cam had a ticking noise from the top end. It turned out to be the Cam shaft shells moving in their housing.


How did you discover that?
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PostPost by: HAIRY » Tue Nov 07, 2017 5:47 pm

It took an experienced engine builder.
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PostPost by: RichardHawkins » Tue Nov 07, 2017 7:05 pm

Vince,

I used Serdi UK in Uxbridge. I am reluctant to recommend anyone as my engine has not run yet. However, John Dorma at Serdi seems a decent person, and I think I am pleased with the work they did, which was to fit new valve guides and seats. Basically they were correcting errors made by Coventry Boring and metalling.

Hope Uxbridge is close enough.

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PostPost by: vincereynard » Wed Nov 08, 2017 6:47 pm

RichardHawkins wrote:Vince,

I used Serdi UK in Uxbridge. I am reluctant to recommend anyone as my engine has not run yet. However, John Dorma at Serdi seems a decent person, and I think I am pleased with the work they did, which was to fit new valve guides and seats. Basically they were correcting errors made by Coventry Boring and metalling.

Hope Uxbridge is close enough.

Richard Hawkins


Thanks Richard.
I've given them a call and John seems interested. Now all I have to do is pull the head of again.
The idea is to see if first it would be viable to rebore the sleeves to take oversize (+.002") followers. That would eliminate the need to heat the head etc.

Uxbridge is fine. Straight down the A413 or a quick flip across country - Pinewood Studios / Iver etc
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PostPost by: JJDraper » Thu Nov 09, 2017 9:03 am

Sort of Bucks area (Northampton) - you could try Cylinder Head Services - I have used them on the recommendation of a serious Lotus specialist. They know what a Lotus twin cam cylinder head is..

http://www.cylinderheadservices.com/

Jeremy
PS they recently moved premises, and I haven't been there yet.
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PostPost by: Foxie » Fri Nov 10, 2017 6:48 pm

rgh0 wrote:When measuring up the sleeve and follower you need to measure top, middle and bottom as the follower wears in a barrel shape and the sleeve in an hour glass shape.
Rohan


I found this out at length. Phil Price at Connaught Engines did a great job refitting new follower sleeves. :)
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PostPost by: reb53 » Sun Nov 12, 2017 5:48 am

HAIRY wrote:My Twin Cam had a ticking noise from the top end. It turned out to be the Cam shaft shells moving in their housing.


Are you able to elaborate a little ?

Can't imagine they were spinning, ( ! ), but assume they were loose in some way ?

I ask because I'm accumulating a mental dossier of weird Twink noises as my engine seems to be acquiring them all now as it gets older..... :)

Ralph.
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