Cam Followers worn
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Post by: rgh0 » Tue May 23, 2006 7:39 am
Rae
You will almost certainly find that the follower is worn into a barrel shape and the sleeve is worn into a hourglass shape. Depending on how bad the wear is you may be able to just replace the followers or you may need to put new sleeves in the head also. Alternatively you can have the sleeve rebored and fit oversized followers which are available.
The cam lobes will also need rebuilding by spray welding and regrinding or you will need to start with new or second hand cams and have them reground if you dont want to spray weld hard facing on your existing cams.
When you do this work it is critical to do 3 things especially if spray welding the cams to rebuild and using the steel followers which are the only type available.
1. Check the hardness of the followers from the supplier and then talk to your cam grinder about the hard facing material he uses to rebuild cams and select a material with a suitable hardness difference for the cam lobes. I normally specify a 10 Rc difference, it does not matter whether its harder or softer provided both are within approximately 50 to 70 Rc. Steel is more prone to galling than cast iron and the hardness difference helps prevent this. Be guided by your cam grinder in this as he should know what to recommend, if he does not know what you are talking about go to another cam grinder who does.
2. Have both the cam followers and cam lobes phosphate treated. This puts a thin layer on the parts which helps the initial break in.
3. Use a running in oil for the first 500 miles.
regards
Rohan
You will almost certainly find that the follower is worn into a barrel shape and the sleeve is worn into a hourglass shape. Depending on how bad the wear is you may be able to just replace the followers or you may need to put new sleeves in the head also. Alternatively you can have the sleeve rebored and fit oversized followers which are available.
The cam lobes will also need rebuilding by spray welding and regrinding or you will need to start with new or second hand cams and have them reground if you dont want to spray weld hard facing on your existing cams.
When you do this work it is critical to do 3 things especially if spray welding the cams to rebuild and using the steel followers which are the only type available.
1. Check the hardness of the followers from the supplier and then talk to your cam grinder about the hard facing material he uses to rebuild cams and select a material with a suitable hardness difference for the cam lobes. I normally specify a 10 Rc difference, it does not matter whether its harder or softer provided both are within approximately 50 to 70 Rc. Steel is more prone to galling than cast iron and the hardness difference helps prevent this. Be guided by your cam grinder in this as he should know what to recommend, if he does not know what you are talking about go to another cam grinder who does.
2. Have both the cam followers and cam lobes phosphate treated. This puts a thin layer on the parts which helps the initial break in.
3. Use a running in oil for the first 500 miles.
regards
Rohan
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rgh0 - Coveted Fifth Gear
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Post by: rgh0 » Tue May 23, 2006 7:40 am
Rae
You will almost certainly find that the follower is worn into a barrel shape and the sleeve is worn into a hourglass shape. Depending on how bad the wear is you may be able to just replace the followers or you may need to put new sleeves in the head also. Alternatively you can have the sleeve rebored and fit oversized followers which are available.
The cam lobes will also need rebuilding by spray welding and regrinding or you will need to start with new or second hand cams and have them reground if you dont want to spray weld hard facing on your existing cams.
When you do this work it is critical to do 3 things especially if spray welding the cams to rebuild and using the steel followers which are the only type available.
1. Check the hardness of the followers from the supplier and then talk to your cam grinder about the hard facing material he uses to rebuild cams and select a material with a suitable hardness difference for the cam lobes. I normally specify a 10 Rc difference, it does not matter whether its harder or softer provided both are within approximately 50 to 70 Rc. Steel is more prone to galling than cast iron and the hardness difference helps prevent this. Be guided by your cam grinder in this as he should know what to recommend, if he does not know what you are talking about go to another cam grinder who does.
2. Have both the cam followers and cam lobes phosphate treated. This puts a thin layer on the parts which helps the initial break in.
3. Use a running in oil for the first 500 miles.
regards
Rohan
You will almost certainly find that the follower is worn into a barrel shape and the sleeve is worn into a hourglass shape. Depending on how bad the wear is you may be able to just replace the followers or you may need to put new sleeves in the head also. Alternatively you can have the sleeve rebored and fit oversized followers which are available.
The cam lobes will also need rebuilding by spray welding and regrinding or you will need to start with new or second hand cams and have them reground if you dont want to spray weld hard facing on your existing cams.
When you do this work it is critical to do 3 things especially if spray welding the cams to rebuild and using the steel followers which are the only type available.
1. Check the hardness of the followers from the supplier and then talk to your cam grinder about the hard facing material he uses to rebuild cams and select a material with a suitable hardness difference for the cam lobes. I normally specify a 10 Rc difference, it does not matter whether its harder or softer provided both are within approximately 50 to 70 Rc. Steel is more prone to galling than cast iron and the hardness difference helps prevent this. Be guided by your cam grinder in this as he should know what to recommend, if he does not know what you are talking about go to another cam grinder who does.
2. Have both the cam followers and cam lobes phosphate treated. This puts a thin layer on the parts which helps the initial break in.
3. Use a running in oil for the first 500 miles.
regards
Rohan
-
rgh0 - Coveted Fifth Gear
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Post by: wobblyweb » Tue May 23, 2006 9:40 am
Yes Rohan, the 2 followers are barrel shaped. The movement is greater when pulled out of the sleeeve. there is not much however when the follower sits fully home. It is difficult to determine the how much movement there should be but the 2 worn followers do have more than the others and if i replace with good followers the movement is reduced. I will try 2 new followers and am tempted to re fit the cam !!
I suppose the worst that will happen is the lobe will wear and the valve will not open fully ? Basically I dont want to remove the head and loose all my summer driving whilst fixing.
I will keep an eye on it and strip it after the summer, if it lasts that long.
One other thing, why only 2 followers why not even wear on them all.
Rae
I suppose the worst that will happen is the lobe will wear and the valve will not open fully ? Basically I dont want to remove the head and loose all my summer driving whilst fixing.
I will keep an eye on it and strip it after the summer, if it lasts that long.
One other thing, why only 2 followers why not even wear on them all.
Rae
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wobblyweb - Second Gear
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Post by: rgh0 » Tue May 23, 2006 11:26 am
Rae
You will find all the followers and sleeves worn. Random variation just means some wear more than others.
Putting new followers in and you will probably be OK for a limited number of miles but the life will be very short with the lobe wear you have on the cams. I would at least get the cam rebuilt if you want to last the summer.
regards
Rohan
You will find all the followers and sleeves worn. Random variation just means some wear more than others.
Putting new followers in and you will probably be OK for a limited number of miles but the life will be very short with the lobe wear you have on the cams. I would at least get the cam rebuilt if you want to last the summer.
regards
Rohan
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rgh0 - Coveted Fifth Gear
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Post by: twincamman » Wed May 24, 2006 8:39 am
You may be experiencing a oil starvation problem in the head at the cams ---though the manual recommends a 600 idle[ tick over] I use 900 to 1000 to insure a high enough oil supply to the top end ---ED
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