Rocker arm geometry
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Joined: Jun 2008
Posts: 68
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From: Murphy Texas
Rocker arm geometry
I am putting my new engine together- trying to determine the correct push rod length. I have a hydraulic roller and bought Comp Magnum 1.6 roller tip rocker arms. (Not the full roller just the tip) The problem is no matter how high or low the rocker arm sits on the stud the roller is out close to the outside edge of the valve stem. Is this the way the 1.6 rocker ends up, and is it ok there? I have never used 1.6's and was wondering if they are supposed to be closer to the center of the valve stem.
Thanks
Thanks
Melting Slicks
Joined: Apr 2002
Posts: 2,337
Likes: 14
From: Norfolk VA
You can contact Comp cams and tell them of your setuup. I'm sure others will reply to assist with this issue as well. I'm sure you are already aware of the importance of proper valve train geometry. Yes the roller tip must be centered over the valve stem. Sounds as if these rockers are not self aligning (as with most are not I believe) Do you have aluminum heads? What I can tell you if you may need hardened pushrods as you may have to adjust the guideplates on the heads. I'm watching this b/c I'm waiting for my new cam to arrive and i also wonder if I will have to have longer pushrods. I have crane cams 1.6 roller tip rockers on now. I'm keeping an eye on this thread as I'm in the same boat as you.
Le Mans Master
Joined: Dec 2006
Posts: 5,557
Likes: 9
From: Oquirrh Mountains
St. Jude Donor '09
There's way too many variables here for a one size fits all pushrod length. But, shorter pushrods will bring the contact patch towards the intake ports. To get the geometry correct, you will need two lightweight check springs, I bought mine from the hardware store and an adjustable pushrod. Install the lightweight springs on #1 cylinder.
Here's the procedure:
http://www.compcams.com/Products/CC-...rods%27-0.aspx
Make sure you use the lightweight springs. If you are using hydraulic lifters, they will collapse all the way before the valves open; resulting in incorrect measurements.
Here's the procedure:
http://www.compcams.com/Products/CC-...rods%27-0.aspx
Make sure you use the lightweight springs. If you are using hydraulic lifters, they will collapse all the way before the valves open; resulting in incorrect measurements.
Last edited by Ben Lurkin; Apr 6, 2011 at 09:33 PM.
Thread Starter
Advanced
Joined: Jun 2008
Posts: 68
Likes: 0
From: Murphy Texas
There's way too many variables here for a one size fits all pushrod length. But, shorter pushrods will bring the contact patch towards the intake ports. To get the geometry correct, you will need two lightweight check springs, I bought mine from the hardware store and an adjustable pushrod. Install the lightweight springs on #1 cylinder.
Here's the procedure:
http://www.compcams.com/Products/CC-...rods%27-0.aspx
Here's the procedure:
http://www.compcams.com/Products/CC-...rods%27-0.aspx
Last edited by rham; Apr 6, 2011 at 09:51 PM.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
You do understand the differnet lengths of pushrods? Is your adjustable checker for the shorter length?
H-rollers are tall lifters so they use @7.200 inch long
Retro h-roller use 7.300 long
flat lifters and solid rollers @ 7.800 standard through 8.000 for .200 longer
H-rollers are tall lifters so they use @7.200 inch long
Retro h-roller use 7.300 long
flat lifters and solid rollers @ 7.800 standard through 8.000 for .200 longer
Last edited by gkull; Apr 7, 2011 at 10:02 AM.
Drifting
Joined: Aug 2005
Posts: 1,682
Likes: 3
From: League City TX
It is way more important that you limit the amount of rocker sweep across the top of the valve.
If the pattern is a bit outside but really narrow I would call it good and run it.
One problem with hydraulic roller lifters is that when you spin the motor over to check your pattern, the lifters are likely to collapse. If that happens you cant properly check the pattern.
And since hydraulic roller lifters are taller than solid rollers you cant substitute a solid lifter to do it either, though low travel hydraulic roller lifters do exist.
If your lifters are collapsing, lightweight "checking" valve springs can come in handy.
It looks like Ben Lurkin already covered this last part above. I guess I need to pay better attention.
Last edited by DRIVESHAFT; Apr 7, 2011 at 12:46 PM.
