Valve lash, With WEBCAM #494 |
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Valve lash, With WEBCAM #494 |
jeffdon |
Mar 13 2010, 06:09 PM
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#1
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
Ran the 2056 on the stand for a last time to get the oil warm, and do the initial change, and get her ready for installation. Did another valve check. Which got me to thinking.
I am setting it to the spec that came with the cam, .006 for both exhaust and intake. Lift (.465) and duration (280 deg.) are the same for both valves. Question is, if exhaust valves expand more due to heat than intake, why does webcam recommend .006 for both? Why not .006 and .008 as is standard? It SEEMS to be running pretty well, but I know i have a good deal of fooling around with jets and such once its on the road and i can test her under load. At one point at about 3500 rpm it started firing back through No 4., but that was right about the time i was running out of gas in my temp. tank. I shut it off, and got a big pop and some flame out the tail pipe. I would really like address/double check anything now, as its way easier accesing things on the stands. |
jeffdon |
Mar 21 2010, 01:16 PM
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#2
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
Not to question your experience, Jake, of which i have utmost respect. Just trying to learn.
If your valve adj. and valve stem are in perfect alignment at mid stroke, seem like your going to be out of alignment for the rest of the stroke either before or after the midpoint. Doesnt this also cause loading on the valve? IE in Marks drawings as the adjuster comes down, seems like the top of the blue line would move left. As it goes up, it the top would swing closer to the redline, right? |
Jake Raby |
Mar 21 2010, 01:27 PM
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#3
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Not to question your experience, Jake, of which i have utmost respect. Just trying to learn. If your valve adj. and valve stem are in perfect alignment at mid stroke, seem like your going to be out of alignment for the rest of the stroke either before or after the midpoint. Doesnt this also cause loading on the valve? IE in Marks drawings as the adjuster comes down, seems like the top of the blue line would move left. As it goes up, it the top would swing closer to the redline, right? Yes, but at mid-lift the valve has the most force against the guide, which is what you need to reduce. The very issue you mention is exactly WHY the swivel foot valve adjuster is such a worthy upgrade. Follow the procedure I outlined, its the same procedure that most all builders follow, not just me. I do this with every engine I build, from 36 HP to over 500 HP roller turbo engines. This procedure when used in our FP race engine keeps valve guides in service for two seasons of 9,000 RPM operation. It works. |
jeffdon |
Mar 21 2010, 01:54 PM
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#4
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Senior Member Group: Members Posts: 1,094 Joined: 24-October 06 From: oakland, ca Member No.: 7,087 Region Association: None |
Not to question your experience, Jake, of which i have utmost respect. Just trying to learn. If your valve adj. and valve stem are in perfect alignment at mid stroke, seem like your going to be out of alignment for the rest of the stroke either before or after the midpoint. Doesnt this also cause loading on the valve? IE in Marks drawings as the adjuster comes down, seems like the top of the blue line would move left. As it goes up, it the top would swing closer to the redline, right? Yes, but at mid-lift the valve has the most force against the guide, which is what you need to reduce. The very issue you mention is exactly WHY the swivel foot valve adjuster is such a worthy upgrade. Follow the procedure I outlined, its the same procedure that most all builders follow, not just me. I do this with every engine I build, from 36 HP to over 500 HP roller turbo engines. This procedure when used in our FP race engine keeps valve guides in service for two seasons of 9,000 RPM operation. It works. Thanks for the (continuing) education! |
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