QUESTION
I believe I may have one or two worn out cam followers as I keep getting a intermediate tappet noise while idling .
I have checked all clearance and reset twice now but not able to eliminate the tappet noise.
Strange as it is not constant but comes and goes, not sure if this is to do with the followers rotating and it does sound quite cyclic while driving.
It is running pretty much the standard followers with I think it is the 0.218" pad, although I am using 304 duration cams.
Any suggestions would be appreciated as well.
P.C. - Perth, Western Australia
ANSWER
If you are experiencing excessive tappet noise and adjustment has failed to reduce the annoyance, then possibly it may be as a result of worn followers.
http://www.lotusmarques.com/info/knowledge-base/1134-lotus-twin-cam-noisy-tappets
The first step in identifying this problem is to remove the camshafts so you can access the followers.
These should be measured using a micrometer at the top, at the middle and at the bottom of the follower.
They have a barrel shaped wear pattern where the follower wall tapers from the middle to either end.
If possible, you should also measure the cast iron sleeves the followers run in (if you have a late model cylinder head)
The bore in the follower sleeve should be 1.375"
A new cam follower will measure 1.374" in diameter.
This means there is an overall clearance of just 0.001"
Once the clearance approached 0.002" to 0.003" then an audible click can be heard (the follower "wobbles" as the cam lobe rotates)
If the cam follower sleeve is badly worn, the just replacing the followers will NOT eliminate the clicking sound.
If this is the case, the follower guide sleeves should be replaced.
The friction pad thickness on a standard Lotus twin cam follower is 0.220"
Copyright © 2015 Lotus Marques
I believe I may have one or two worn out cam followers as I keep getting a intermediate tappet noise while idling .
I have checked all clearance and reset twice now but not able to eliminate the tappet noise.
Strange as it is not constant but comes and goes, not sure if this is to do with the followers rotating and it does sound quite cyclic while driving.
It is running pretty much the standard followers with I think it is the 0.218" pad, although I am using 304 duration cams.
Any suggestions would be appreciated as well.
P.C. - Perth, Western Australia
ANSWER
If you are experiencing excessive tappet noise and adjustment has failed to reduce the annoyance, then possibly it may be as a result of worn followers.
http://www.lotusmarques.com/info/knowledge-base/1134-lotus-twin-cam-noisy-tappets
The first step in identifying this problem is to remove the camshafts so you can access the followers.
These should be measured using a micrometer at the top, at the middle and at the bottom of the follower.
They have a barrel shaped wear pattern where the follower wall tapers from the middle to either end.
If possible, you should also measure the cast iron sleeves the followers run in (if you have a late model cylinder head)
The bore in the follower sleeve should be 1.375"
A new cam follower will measure 1.374" in diameter.
This means there is an overall clearance of just 0.001"
Once the clearance approached 0.002" to 0.003" then an audible click can be heard (the follower "wobbles" as the cam lobe rotates)
If the cam follower sleeve is badly worn, the just replacing the followers will NOT eliminate the clicking sound.
If this is the case, the follower guide sleeves should be replaced.
The friction pad thickness on a standard Lotus twin cam follower is 0.220"
Copyright © 2015 Lotus Marques
