The situation is the same Mike, the contact point is all that matters whether it's a roller or not.Stocker wrote:What about stamped steel rockers , that have no roller ?
Mike...
Valve train geometry
Moderator: Team
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ozrace
Good Morning Gentlemen
I hope not to beat this to death. I am in the middle of working out my push rod length. I went to crowers website looking for rocker studs and found the spot regarding rocker/pushrod geomtry. They have a good picture(s) of this. Soooooo.... I got my geometry so that at midlift the roller is mid-point on the valve stem and about .03 towards the stud when the valve is closed and also .03 towards the stud at full lift. I say okee dokee that looks ok. But then I saw that in one of their diagrams they wanted ( at half lift) to have 90* between the pivot point and the pushrod centerline and 90* between the pivot point and the valve centerline. Well I fiddled with this and there is no way I can get my Comp rockers to work at this depicts. When I get the conteact pattern as I first outlined I have 90* between the pivot point and the valve centerline and about 80* between the pivot point and pushrod centerline( at half lift ) to achieve those angles I would have to have a completly different rocker - one where the pushrod cup is dropped down.
I am working with a Ford 302 roller moter and earlier heads( 66 289). I put some stock BBC studs in it but I am going to put the longer BBC studs in it with the hardened washers so that I can get the shank of the stud up in the trunion just as a gentlemen suggested in a different post - I like that idea.
Thanks
Jim
I hope not to beat this to death. I am in the middle of working out my push rod length. I went to crowers website looking for rocker studs and found the spot regarding rocker/pushrod geomtry. They have a good picture(s) of this. Soooooo.... I got my geometry so that at midlift the roller is mid-point on the valve stem and about .03 towards the stud when the valve is closed and also .03 towards the stud at full lift. I say okee dokee that looks ok. But then I saw that in one of their diagrams they wanted ( at half lift) to have 90* between the pivot point and the pushrod centerline and 90* between the pivot point and the valve centerline. Well I fiddled with this and there is no way I can get my Comp rockers to work at this depicts. When I get the conteact pattern as I first outlined I have 90* between the pivot point and the valve centerline and about 80* between the pivot point and pushrod centerline( at half lift ) to achieve those angles I would have to have a completly different rocker - one where the pushrod cup is dropped down.
I am working with a Ford 302 roller moter and earlier heads( 66 289). I put some stock BBC studs in it but I am going to put the longer BBC studs in it with the hardened washers so that I can get the shank of the stud up in the trunion just as a gentlemen suggested in a different post - I like that idea.
Thanks
Jim
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pparaska
Thank you so much for pointing out how Comp's drawing shows a really bad geometry example.
I thought going to a valvetrain company's website would give me the correct theoretical info. So wrong.
I'd like to thank those that have posted about the correct pushrod length giving the smallest pattern across the valve.
I was out in the garage playing with an adjustable pushrod and found that differing lengths gave me wider patterns. It's a 400 SB Chevy, that's been decked TOO FAR (average deckheight of about +0.010" on the even bank, +0.019" on the odd bank. The heads are Canfield 215cc, with +0.100" longer valves. So shorter deck than the typical zero deck block, and non-standard heads, so I knew I'd need to look at custom length pushrods. I'm using Comps Pro Magnum rockers (1.52:1).
I can get a pretty small pattern that starts inboard (stud side) from the center a bit, and goes to the center at mid-lift, and then out and back to near center but outboard at max lift.
With a shorter pushrod, I can get it to go to the center at mid-lift, but it starts much further inboard and therefore has a wider pattern.
I'll go with the former instead of the latter!
Great site!!!
I thought going to a valvetrain company's website would give me the correct theoretical info. So wrong.
I'd like to thank those that have posted about the correct pushrod length giving the smallest pattern across the valve.
I was out in the garage playing with an adjustable pushrod and found that differing lengths gave me wider patterns. It's a 400 SB Chevy, that's been decked TOO FAR (average deckheight of about +0.010" on the even bank, +0.019" on the odd bank. The heads are Canfield 215cc, with +0.100" longer valves. So shorter deck than the typical zero deck block, and non-standard heads, so I knew I'd need to look at custom length pushrods. I'm using Comps Pro Magnum rockers (1.52:1).
I can get a pretty small pattern that starts inboard (stud side) from the center a bit, and goes to the center at mid-lift, and then out and back to near center but outboard at max lift.
With a shorter pushrod, I can get it to go to the center at mid-lift, but it starts much further inboard and therefore has a wider pattern.
I'll go with the former instead of the latter!
Great site!!!