morpwr
Veteran Member
Just measuring from the valve tip to bottom of cam bore. There is .025 difference between lowest and highest. Is this normal? Anybody have an actual dimension please?
Valve stem height
- Thread starter morpwr
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A5INKY
Vendor , w/Business number
When valve contact was suspected I have always measured down from the valve cover surface to each valve tip. These measurements have yielded numbers that were within a couple thousandths of each other, though I don't recall the actual figure. Whenever I have found an outlier this way it has been a clearly bent valve.
Not sure how you were able to accurately measure the way you did. A 0.025" difference would be absolutely huge though. I'd be digging deeper if I found installed height variance that wide.
Not sure how you were able to accurately measure the way you did. A 0.025" difference would be absolutely huge though. I'd be digging deeper if I found installed height variance that wide.
morpwr
Veteran Member
No valve contact
I set the head up on CNC mill with the valves installed. Shimmed the head so clearance for valve heads and level side to side front to back with in .001. Took dial indicator and measured from valve tip to bottom of cam journal with out bearings. Started with one valve as zero and measured along. Found lowest was .007 to highest which was .018 above. These are stock straight valves with springs on. Is there a spec for the valve tip to some point on the head so the lifters are in their operating range?
I set the head up on CNC mill with the valves installed. Shimmed the head so clearance for valve heads and level side to side front to back with in .001. Took dial indicator and measured from valve tip to bottom of cam journal with out bearings. Started with one valve as zero and measured along. Found lowest was .007 to highest which was .018 above. These are stock straight valves with springs on. Is there a spec for the valve tip to some point on the head so the lifters are in their operating range?
A5INKY
Vendor , w/Business number
Not so sure VW provides reman specs such as this. If I were you I'd get ahold of Frank Irving (Franko6) and perhaps he'd share the spec and protocol he uses.
morpwr
Veteran Member
Thank You
I will try and get hold of him. He has some good technical info on the forum. Thank you for the suggestion.
I will try and get hold of him. He has some good technical info on the forum. Thank you for the suggestion.
CNGVW
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If a Good valve job is done they should be with in a few thousandths.
If it is a used head it could have the seats pounded in a bit valve faces with wear.
The key is to have the lifter/cam assembled pushing the plunger in about 1/4 way of its travel. On some of my gas engines I would set up the engine to just have like .010 of pre load on the lifters. This was so if the lifter hydro-lock it pumped up in the high RPM range it would not push the valve in to the piston.
If it is a used head it could have the seats pounded in a bit valve faces with wear.
The key is to have the lifter/cam assembled pushing the plunger in about 1/4 way of its travel. On some of my gas engines I would set up the engine to just have like .010 of pre load on the lifters. This was so if the lifter hydro-lock it pumped up in the high RPM range it would not push the valve in to the piston.
morpwr
Veteran Member
More Measuring
OK. Thank you so far. I will measure another head. Also can measure cam base circle and lifter thickness to get minimum value. The subtract .01 for lifter pre load. Thank you
OK. Thank you so far. I will measure another head. Also can measure cam base circle and lifter thickness to get minimum value. The subtract .01 for lifter pre load. Thank you
morpwr
Veteran Member
Values
Measured another head. Value from top of valve to bottom of cam bore was 1.112, about .01 more than other head. Both heads are around 400,000 kms. Cam base circle is 2.086, and cam bore in head is 1.26. This leaves the base circle about .41 below bottom of cam bore. I took a 1" micrometer to measure the thickness of the lifter from the cam contact surface to the valve contact button. Seems most of them are about .75 with the button sprung out. The button will compress approx. .02- .025. This makes CNGVW about right for .01 preload on the lifter. Doing the math the valve tip should be 1.150 approx below the bottom of cam bore with out bearing. Best valves are 1.112. This would make me think the valves and valve seats have eroded almost .04. Any body seen this much wear? So at this point does anybody have a 1" micrometer and a stock lifter to verify the lifter is .75 thick approx. There must be some people who have ground their valves and seats, and have a installed height from the valve tip to some point on the head. I presume if you had the cam installed the lifter should be able to be pressed down to remove the play and a .01 feeler gauge or near there . Any suggestions please.
Measured another head. Value from top of valve to bottom of cam bore was 1.112, about .01 more than other head. Both heads are around 400,000 kms. Cam base circle is 2.086, and cam bore in head is 1.26. This leaves the base circle about .41 below bottom of cam bore. I took a 1" micrometer to measure the thickness of the lifter from the cam contact surface to the valve contact button. Seems most of them are about .75 with the button sprung out. The button will compress approx. .02- .025. This makes CNGVW about right for .01 preload on the lifter. Doing the math the valve tip should be 1.150 approx below the bottom of cam bore with out bearing. Best valves are 1.112. This would make me think the valves and valve seats have eroded almost .04. Any body seen this much wear? So at this point does anybody have a 1" micrometer and a stock lifter to verify the lifter is .75 thick approx. There must be some people who have ground their valves and seats, and have a installed height from the valve tip to some point on the head. I presume if you had the cam installed the lifter should be able to be pressed down to remove the play and a .01 feeler gauge or near there . Any suggestions please.
morpwr
Veteran Member
Mystery solved
The valve measurement is good. Sorted through the lifters and found some with more travel. A good lifter will have almost .100 travel in the plunger that contacts the valve. So taking up .04 of travel is no problem. Some of the lifters only move .02. I think the internal piston and check valve is seized reducing the travel. I have tried bleeding out the oil but no luck. So time for new set of lifters and valves can be .03 difference in height no problem.
The valve measurement is good. Sorted through the lifters and found some with more travel. A good lifter will have almost .100 travel in the plunger that contacts the valve. So taking up .04 of travel is no problem. Some of the lifters only move .02. I think the internal piston and check valve is seized reducing the travel. I have tried bleeding out the oil but no luck. So time for new set of lifters and valves can be .03 difference in height no problem.