Cam Timing: Can someone explain this line from my Webcam instruction sheet?

[LeeH]

I want to make sure I'm not messing up the cam timing. Since I had piston/valve interference on my first try, I want to make sure I'm interpreting Wayne's book and the cam instruction sheet properly before I proceed.

From the start I've been following Wayne's cam timing instructions with a goal of matching the "Set @ 1.9 - 2.2 mm/ .10 lash" instruction from the sheet. Based on that I adjusted the valves for #1 and #4 instake and assumed my goal is to be somewhere between 1.9 - 2.2 mm of lift at Z1 for each side.

However, I don't understand this line on the sheet: "Valve timing is checked with zero valve lash @ .050 inches of valve lift." What does that mean?

[SP2]

I am gonna guess here, but I believe that means if the valve adjustment is set to zero (as opposed to 0.1 mm), when the cam is in the correct orientation it will interact with the rocker enough to depress the valve, i.e. open it, by 0.050 inches, or 1.27 mm. Just a guess though.

But anyway, you are doing it correctly. How are you tensioning the chains? Could that be the problem?

[dfink]

If you have aftermarket or non-stock cams use the timing they provided.
Make sure that the pin is out on the right side and the bolt is loose.
Set the valve so that it has no play.
Make sure keyway is pointing to top and that crank is on Z1 and that pin in inserted.
Turn crank approximately 360 degrees untill dial reads .050 in or 1.27mm remove the pin loosen bolt and turn crank until Z1 lines up with case line.
Insert the pin turn 720 degrees and you should be back at .050 in
It is easiest if you always have to turn the crank clockwise to make the final adjustment. If not then any slop in the chain will effect your adjustment. If you have to overcompensate on the first adjustment so when making the final you are turning the crank clockwise when looking at it from the pully end.
Also make sure that #1 and #4 are opening on different revolutions. It is possible to have them opening at the same time.
After timing is set and confirmed don't forget to set the valve clearance or "lash" to 1mm or .004" I would suggest using the dial indicator for this as it is the most accurate and easy to do with the engine out.

[SP2]

Hmm, that doesn't sound right to me. If valve clearance is the same as valve adjustment, then the measurement it 0.1mm and you can't do this with a dial indicator. I would think you are doing it correctly already. 1.9-2.2 mm with valve adjusted 0.1 mm TDC.

But why guess. If you think an error in timing is why your #6 valve is not clearing, why don't you call WebCam up (I think you said that was the manufacturer?) and ask them, to be sure. Let us know what you learn, especially about the "valve timing" question you had earlier. Thanks.

[LeeH]

I called WebCam. The person who answers the phone there seems to have little knowledge and be trained to keep callers away from the people who hold the knowledge. She had me call Precision Motion. I talked to a mechanic there who said to follow the 1.9 - 2.2mm instruction.

I think the .050 inches figure that's printed on the bottom may be for most cams they make and the 1.9-2.2 mm is specific to this cam.

The guy I talked to said they always shoot for the high side of the range... and there's never a piston/valve clearance problem. Which leaves me where I was before - no good explanation for the interference.

[dfink]

If you read through all the cam timing posts. Some cams are set with zero lash and some are set with the 1mm lash. Just depends on how they wish to represent it.
Valve clearance is an completely different issue.
If it is done with zero lash then you must set the "lash" or rocker gap to 1mm or .004in. [EDIT] set gap after adjustment of timing.
I assume the zero lash method is to improve accuracy

[SP2]

dfink,

do you mean 1 mm or 0.1 mm. I think Lee's 1.9-2.2 spec is for 0.1mm valve adjustment.

[dfink]

Sorry you are correct .1mm = .004"
The methodology however I believe is correct.

[boxermania]

Leeh

The zero valve lash instruction opens the valve the maximum amount at the specified .050" cam lift. At this point the 1.9 to 2.2 mm setting will insure no valve piston interference.

Obviously if done wrong one will find, after rotating the crankshaft, that there will be valve/piston interference. That's why it pays to check two or three times after timing the cams. Make absolutely shure that you rotate the crankshaft in the direction of normal rotatation.

Hope this helps

[LeeH]

Originally posted by boxermania
The zero valve lash instruction opens the valve the maximum amount at the specified .050" cam lift. At this point the 1.9 to 2.2 mm setting will insure no valve piston interference.

Al,

Can you clarify the above. I've tried to follow Wayne's instructions as closely as possible, but still have interference when within the spec as I understand it. The way I had the car set up was 2.1mm of lift at TDC with .10mm of valve lash.

So... to be clear, I adjusted the valve to .10mm, then set the cams so that there was 2.1mm of lift at Z1. At this setting I had interference on #4 and #5 (curious that #3 cleared). Was this the correct method?

[Jeff Alton]

Can you describe the procedure you are using? State where the cams are positioned when you start as well. Maybe even post some pics.

Is there only a clearance issue on the right bank? 4-6? If so, I really think that cam is 180 degrees out.

Cheers

[Eagledriver]

There seems to be lots of guessing and missinformation in this thread. Here are some non guesses. I have no idea what boxter mania is trying to say. Lee, you have the right idea in all that I've read of your post.

The part of the instructions about .050 inches for measuring is how they define the cam duration. It has nothing to do with your measurements. In other words when they say the cam has 295 degree duration on the intake they mean that the cam has .050 lift at the start of that 295 and at the finish of 295. It is a way to standardize the measurement in a meaningful way. Some companies use different numbers in their definitions so that is why they included that in your instructions.

You should set standard valve clearances (.004 inches) before setting the cam timing unless otherwise instructed by the manufacturer. Some may use zero lash although I've never seen it.

I don't understand why your engine seems to be having clearance issues on only some cylinders. When you are setting the 2.1mm is the intake valve just starting to open to get to that number or is it on it's way back down? It should just start to open as you approach TDC on the overlap cycle and end up at your 2.1mm as you hit TDC.

Check your pulley markings and make sure you really are using the correct Z1 and that the pulley is indexed correctly to the crank.

-Andy

[dfink]

No I believe that is too much lift.
remove all rocker to valve gap then....
1) Put crank at Z1
2) Place left cam so key-way is pointing directly up
3) place pin in sprocket and tighten bolt
4) make sure right side pin is out and bolt is loose so cam does not turn
5) Place dial indicator on top of valve spring retainer
6) turn crank in direction of rotation "clockwise" as viewed from pulley until dial indicator reads .050 inches or 1.27mm then stop turning. Go slow so you don't go past.
7) hold cam in place and take bolt out and remove pin
8) turn crank until Z1 lines up with case split
Again if Z1 has gone past case split it is difficult to accurately turn back due to chain play.
9) put pin back in and replace bolt.

2.1mm of lift is way too much your directions from webcam say .050 with zero lash. This means you must remove all the gap between the rocker and the valve before setting the timing. After timing is set then re-adjust the rocker gap. Wayne's book does not take into account the many different cam combinations that are available. You should use the specs that were provided by webcam.

[SP2]

dfink,

I think you are wrong. If you look at Lee's other post, the 2.1 mm lift with 0.1 mm valve adjustment IS the direction from webcam.

[LeeH]

Wow. Interesting to see the different interpretations. This is the info from WebCam:

[dfink]

Originally posted by LeeH
However, I don't understand this line on the sheet: "Valve timing is checked with zero valve lash @ .050 inches of valve lift." What does that mean?

This is where I am getting my info from the first question that started this thread. Also .050" is very comparable to the 964 grind that I just put in though it was set with .004 rocker gap. If he is having valves hit then something is wrong and since in his first question he states a lift of .050 and he is trying to set to nearly 1.5 times this I would assume this is the trouble. Perhaps a scan of the spec sheet for the cam would clear up the confusion. My thought was he is following directions for a stock cam from Wayne's book but he does not have a stock cam. I could be all wrong though would not be the first time.

[dfink]

Well just saw the sheet so I recant all previous statements except sequence which you appear to already have down so I am now also confused. Is the 20/21 grind perhaps just too much cam for the engine.

[Eagledriver]

That comment at the bottom is telling you that the intake opens at 6 degrees before TDC to .050 inches with no lash. If they specified the opening when the valve first cracks open it would be at a different spot.

This should mean that your intake valve will be open .046 when the crank is 6 degrees BTDC. (.050 minus the lash of .004). When you turn the cam further to TDC the valve should be open to your timing number of about 2mm.

-Andy

[dfink]

Very good I get it hope Lee also sees what you are saying. Is there a reason to check this way. Seems that as long as you have proper lift at TDC the rest is just a function of the cam itself.
Also for Lee I think someone already mentioned it but are you sure you don't have the right cam 180 degrees off. If both #1 and #4 are moving at the same time then the right side is 180 off.

[SP2]

Lee,

Your signature says your car is a 72 3.0L. Is this an SC transplanted engine? If so, a 20/21 definitely will fit.

Best Cam Profile For A Stock SC?