Hope this helps to clear up the mystery of valve geometry on a vw head. I borrowed the pic showing the 90deg angles because the picture is worth a thousand words and its for a good cause.
Thank You for breaking it all down to a simple form and I loved the picture of the 90 degree on both sides of the rocker, the valve side & the push rod side at 10:54
If I remember correctly,Oldsmobile many years ago used exhaust valve rotators on some engines and what they got was premature valve seat wear.i can't think of any modern engine that has valves that rotate.also,with the keepers I don't know how it's gonna turn anyway.
That's a great point. And just say they was little to no pressure being applied to the valve stem while it returns to the closed position, then there would be no rocker arm action to make it rotate either.
Great information, nothing beats being able to see how things are done rather than reading about it! I did this with my build about a year ago for the stock rockers and now will be upgrading to 1.4 and needed the refresher. I noticed that when you marked the valve lash cap and rotated the engine the pass was right on the center but it was off to one side. Would that put pressure to one side and possible damage components down the road? I am fairly new to building these engines and want to make sure every end is covered. Thanks for the video!
You are correct .. up/down .. and side to side .. should have zero off-center pushing. I watched a great stobe video of valves and springs at 5000 rpm. Wow .. those stainless valve stems were wiggling like crazy ... like about 1/4" total swing. So .. hitting them off center .. is not a good idea ...
Rotating valves ... that was a concept from the 1940s. And it was a huge failure in many ways. Back hear .. in the real modern world. The valve stem is locked, under constant pressure to the keepers, and the spring's cap. Not to mention, the valve guides are not a lubricated sleeve. Rotating valves ... would just cause a huge bunch of wear ... in a place that you don't want to see wear. All modern engines .. the rocker hits dead center and not side to side (right/left) And Muchachos here explains how to achieve the logics of getting the up and down. Think about it ... we do everything possible to center the valve (up and down) to prevent wear. Sooo.. you should have zero side to side misalignment ?
Thank you so much for the vid but Bro, please help me how do I know I'm at half lift I have a 120 cam. Also I have 1.25 rockers. These are the specs .496" valve lift .397" cam lift 294 degrees of advertised duration. How do I know I'm at half lift??? Do I need to use a dial indicator?
Hi Dan, Most of this info. is pretty much scattered in bits and pieces all over the internet most of the valve geometry forum threads about type 1 engines but only touch on one or two problems and don't explain the rest making it very difficult to under stand the concept. How ever..... there is a good reason for this, there is at least a half dozen or more of rocker styles that this info would not work and a different approach method is a must. So a word to the wise.... Just because this method works for me doesn't mean it will work for you. However this video will give you a pretty good idea on how to approach you situation. Hope this helps :)
You just touched on a subject that is pretty much a huge can of worms. There are hundreds of threads about that and it all really comes down to what you prefer to do because 50% of the people more or less like to lock the valve in place so that it doesn't rotate by grinding the keepers thus pinching the valve stem. This is considered to be high performance modification by many. The engine on this video I locked the valves so that they don't turn.
Hmmmm .. but the valves are unable to rotate because of the valve keepers are locked to the spring cap, that holds the valve. And the spring can't rotate either. This whole rotation thing ... is a bunch of monkey see = monkey repeat.
Thank You for breaking it all down to a simple form and I loved the picture of the 90 degree on both sides of the rocker, the valve side & the push rod side at 10:54
If I remember correctly,Oldsmobile many years ago used exhaust valve rotators on some engines and what they got was premature valve seat wear.i can't think of any modern engine that has valves that rotate.also,with the keepers I don't know how it's gonna turn anyway.
That's a great point.
And just say they was little to no pressure being applied to the valve stem while it returns to the closed position, then there would be no rocker arm action to make it rotate either.
Great information, nothing beats being able to see how things are done rather than reading about it! I did this with my build about a year ago for the stock rockers and now will be upgrading to 1.4 and needed the refresher.
I noticed that when you marked the valve lash cap and rotated the engine the pass was right on the center but it was off to one side. Would that put pressure to one side and possible damage components down the road? I am fairly new to building these engines and want to make sure every end is covered. Thanks for the video!
You are correct .. up/down .. and side to side .. should have zero off-center pushing.
I watched a great stobe video of valves and springs at 5000 rpm.
Wow .. those stainless valve stems were wiggling like crazy ... like about 1/4" total swing.
So .. hitting them off center .. is not a good idea ...
Rotating valves ... that was a concept from the 1940s. And it was a huge failure in many ways.
Back hear .. in the real modern world.
The valve stem is locked, under constant pressure to the keepers, and the spring's cap.
Not to mention, the valve guides are not a lubricated sleeve. Rotating valves ... would just cause a huge bunch of wear ... in a place that you don't want to see wear.
All modern engines .. the rocker hits dead center and not side to side (right/left)
And Muchachos here explains how to achieve the logics of getting the up and down.
Think about it ... we do everything possible to center the valve (up and down) to prevent wear.
Sooo.. you should have zero side to side misalignment ?
Thank you so much for the vid but Bro, please help me how do I know I'm at half lift I have a 120 cam. Also I have 1.25 rockers. These are the specs .496" valve lift
.397" cam lift
294 degrees of advertised duration. How do I know I'm at half lift??? Do I need to use a dial indicator?
hi!
do you speak Spanish?
I've been searching for the translation to spanish of blueprint an engine without luck
how would u do it?
thanks
Where did you come up with this information
Hi Dan,
Most of this info. is pretty much scattered in bits and pieces all over the internet most of the valve geometry forum threads about type 1 engines but only touch on one or two problems and don't explain the rest making it very difficult to under stand the concept. How ever..... there is a good reason for this, there is at least a half dozen or more of rocker styles that this info would not work and a different approach method is a must. So a word to the wise.... Just because this method works for me doesn't mean it will work for you. However this video will give you a pretty good idea on how to approach you situation. Hope this helps :)
this is not the way to do it to my understanding,I read that rockers should be off center to rotate the valves
You just touched on a subject that is pretty much a huge can of worms. There are hundreds of threads about that and it all really comes down to what you prefer to do because 50% of the people more or less like to lock the valve in place so that it doesn't rotate by grinding the keepers thus pinching the valve stem. This is considered to be high performance modification by many. The engine on this video I locked the valves so that they don't turn.
Hmmmm .. but the valves are unable to rotate because of the valve keepers are locked to the spring cap, that holds the valve. And the spring can't rotate either.
This whole rotation thing ... is a bunch of monkey see = monkey repeat.
No manufacturer has used off-center /rotation geometry ... since the 40s. The miracle is that people still repeat it.