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Re: [6pack] Measuring valve lift

To: Joe Santamaria <jsantamaria@optusnet.com.au>, 6pack@autox.team.net
Subject: Re: [6pack] Measuring valve lift
From: "Sally or Dick Taylor" <tr6taylor@webtv.net>
Date: Wed, 27 May 2009 00:52:41 GMT
Joe---This particular reply may be too late in arriving, as I've been out of 
town for a couple of weeks. Still, if you want to know how much the cam lobes 
have worn, (if at all) without actually removing the cam, I know of only one 
proper way to do this. It does require head removal, tho, which shouldn't be a 
big deal. Once the head is off, a dummy pushrod is needed in place of the 
actual pushrod(s). It won't wobble like a real pushrod must do. If you don't 
have one, an illustration of this is shown in Kastner's original Competition 
Prep Manual. I can loan you mine, if you like.

To measure lobe wear, the engine needs to be rotated with the dummy in place. A 
dial indicator, preferrable magnetic based,  placed on the flat top of the 
dummy will show when the cam is on it's base circle, and again when the lobe is 
at it's apex. You'll want to write down these numbers, and do it for all 12 
lobes. The difference between the base circle no. and the tip of the cam lobe 
should be the same for all 12, unless the cam is asymmetric. If it is, then all 
intake should be the same, as should all exhaust.

Dick


-----Original Message-----
From: Joe Santamaria
Sent: Wednesday, May 13, 2009 4:40 AM
To: 6pack@autox.team.net
Subject: [6pack] Measuring valve lift

Hi guys,

I am a regular member of the list for some years now and excuse me as I
don't have a TR6 but have five Saloons all with 2500 PI engines, one with a
TR6 cam, so I find all the content on engines on this list most helpful but
can't participate as much on the TR 6 per se. I'd love to have a TR6 but
unfortunately out of budget at this stage.

I do have a question though, on how to correctly measure valve lift with cam
and rockers in place.

I have tried to rest dial gauge tip on the actual rocker head on top of the
valve but clearly this point rotates through a wide arc and cannot get the
dial indicator tip end to sit on the rocker at this point anyway.

Do you instead rest the dial gauge tip on the screw adjuster and measure
from here assuming a certain rocker ratio or what is the correct method
given cam and rockers are in place.

I understand lift and duration on a TR6 engine is different to a Saloon PI
but this is just a relative measure I am after to compare between motors.

I'm trying to assess any wear in the camshaft without actually removing the
cam to do so.

Many thanks for any pointers on this and also pointers may be on measuring
duration and opening/closing angles.

Cheers

Joe.

2.5PI 1969 Mk1 Saloon Tr6 Cam Overdrive
2.5PI 1972 Mk2 Saloon Overdrive
2.5PI 1969 Mk1 Auto Saloon
2.5PI 1971 Mk2 Saloon Auto
Stag 1976 Auto
2500S Man Overdrive Saloon (SU HS6 Carbs)
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