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Roller rocker centered on the valve stem

steve340 said:
I have been doing engines since I was an apprentice and had never heard of rocker geometry until I purchased an engine blueprinting book about 25 or so years ago.
At least you knew to check it.
That video from Straub is pretty good but the old way of centre of valve at half cam lift still works fine. I have done quite a few engines over the years and your eye is pretty good.
The sweep of the rocker over the valve tip is fairly important. If your sweep on a Mopar is around or less than 1 mm or 0.040 thou you are doing pretty good. A little bit off centre will cause no issues. With the shaft mounted rockers you cannot alter the rocker geometry with push rod length as described in the video.
To alter the geometry on a Mopar you need to move the rocker shaft up or down. It would be nice to move it in or away from the valve also but as we know that cannot happen with the cast in pedestals. A Mopar rocker is pretty short and that is some of the trouble.
To optimise the push rod length put a DTI on the spring retainer and play with the push rod length until you get the most valve lift.
Have the adjuster screw far enough out of the rocker to ensure it is low enough for oil to spray in to the push rod cup. If your push rod is too long I believe you can starve the rocker end of the push rod a bit.
I modify the Harland Sharp, the push rod oiling hole is huge and no oil goes to the rocker tip. I only buy the Hughes ones now.

I will
Click to expand...
great post
couple of things
you can mill off the stands and use new stands to move the shafts up and back- or use B3s kits
Getting max lift method implies that you have the shafts really low making the rocker perpendicular at near max lift
max increases load over nd accelerationa near the nose rquiring tiffer springs
you want most leverage at mis lift so you can slow down to get over the nose
you can't correct geometry with shaft rockers via pushrod length as you can with stud rockers- after moving the fulcrum
going 4 minimum stripe works but you hav to move the shaft
pushrod length is an afterthought
I'll watch the video
most write ups on camgrinders websites do not apply to mopar
read the 4 tech articles on the B3 racing website
 
The Hughes rockers are very good. They have an oil squirter behind the adjuster that hits the ball/cup and an oil dripper out front for the roller. I still needed the B3 Racing shim kit to move the rocker shaft up and away for better geometry.

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I read those B3 articles and they are good stuff. At first I did not realise his shims/spacers lift the shaft and roll it back a bit. They seem like a really good thing and I had never heard of them before.
No one knows everything and you just keep learning.
 
threewood
how well to the adjusters line up with the pushrods
say at half lift
thanks
 
Paul_G said:
Take a look at these please. I think the roller tip is not centered on the valve stem correctly. How can I get the tip to ride in the center? Trick Flow PP240 heads with Harland Sharp rockers made for Eddy and TF heads.

I have the push rod checker tool at 8.785" which leaves about 1 thread exposed below the rocker arm. Right at HS spec.

View attachment 908639
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View attachment 908640
Click to expand...

What you have will work just fine for a typical street strip type of engine. I'd run it just the way it is, especially since it is a hyd roller engine. With a hyd roller you aren't going to be punishing the valve train like you would with a solid roller.
 
What andyf said
do measure your valve tip stripe and report back
post up your compression
the tf heads are already sorta compensated for roller tip rockers and more lift than stock heads
I don't remember but you already have pushrods?
 
wyrmrider said:
What andyf said
do measure your valve tip stripe and report back
post up your compression
the tf heads are already sorta compensated for roller tip rockers and more lift than stock heads
I don't remember but you already have pushrods?
Click to expand...


I can measure the stripe when I get back on the engine.
The engine was built for 10.5:1 static compression.
I juts got the rockers, measuring for push rods now.

andyf said:
What you have will work just fine for a typical street strip type of engine. I'd run it just the way it is, especially since it is a hyd roller engine. With a hyd roller you aren't going to be punishing the valve train like you would with a solid roller.
Click to expand...

I had an email conversation with Harland Sharps Randy Becker. He saw a bunch of pictures that I took of the rocker geometry and said the same thing as you. It is good to run like it is. That is what I am going to do.
 
Paul_G said:
I had an email conversation with Harland Sharps Randy Becker. He saw a bunch of pictures that I took of the rocker geometry and said the same thing as you. It is good to run like it is. That is what I am going to do.
Click to expand...


Good call.
 
Just add some .060" thick Lash Caps to the V/Tips and it will move the tip contact point closer to the Intake side.
You're welcome.
 
That far off-center will cause more wear on the valve guides.
The rocker shaft needs to move up and away from the valves.
 
Is there a downside to using lash caps? If not it might help with push rod selection too.
 
It is more a band aid solution to use lash caps, the position of the rocker shaft relative to the valve tip center and height is not correct.
Using a lash cap will cause the below angle between push rod and adjuster bolt to become worse, which is something you do not want as it increases side load.
More side load increases the chance of material failure.
Also you will loose valve lift as the side-movement increases and therefore the lift reduces.

20200214_175616-jpg.jpg
 
we never got word back on the stripe width
I'd talk with B3 bfore buying pushrods
 
wyrmrider said:
we never got word back on the stripe width
I'd talk with B3 bfore buying pushrods
Click to expand...

My guess would be around 0.080".
It seems to much regardless of the measurement, and besides being so much off-center is another thing.
If this is a fresh build i would rectify it to have a stable valve train.
The B3 kit will correct it without issues for sure, i can highly recommend it.
 
better than .080 which is common
but not 030-.040 which you end up with B3 kit
as andyf said you are most likely ok with your springs and rpm
idk if lash caps would help or make the stripe worse (likely)
do not sweat the center- you are ok
you do not get the side thrust with a roller tip you get with a stock rocker
now if you are a perfectionist like Wietse...
 
wyrmrider said:
now if you are a perfectionist like Wietse...
Click to expand...

Well, perfectionist is a big statement..... I just went through all of it and its fresh at memory
I think it is $200 well spend on going with a B3 kit, if you change to roller tip rocker, you need to correct the rocker shaft position to the right place as the geometry changed a lot.

Adding a lash cap causes the rocker arm to face up more, and with that the angle between the adjuster and push rod becomes more "extreme".
The push rod starts to create a side load against the adjuster screw, there was a post not long ago here from someone who found a rocker cracked in half.
That was because the push rods were too short and had the adjuster screws sticking out too far, which causes the similar effect.
 
Push rods. What I am finding is there is not an off the shelf push rod exactly what I need as it sits right now. There are some a touch short, leaving 3 threads showing under the arm. And some a bit long leaving almost no threads showing under the arm. Spec from HS is 0 to 2 threads showing. Am I better to get the longer ones or shorter ones or custom order?
 
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