Roller rocker centered on the valve stem

[wyrmrider]

yep those with lifter pump up or valve float pay attention
other side of the coin is that valve close is easier

 

[Paul_G]

OK, take a look at this. I wish I had not purchased the Harland Sharp rockers. They suck.

My gross valve lift is .540, half of that is .270. So .270 is where you want the geometry square right? Square means to do this, draw a line on the side of the rocker from the center of the trunion, to the center of the roller tip, am I still right? Now at 1/2 valve lift, in my case .270, you want that line I drew on the side of the rocker, 90° to the valve stem, that is what square is, do I have that right?

I got tired of waiting for a friend to get back if he had a valve spring compressor to use on the engine, or even make one myself, so I just bottomed out the lifter with the adjustable push rod checker and rotated the crank till I had .270 lift on the valve I am measuring. Now look at the pics. This is the best I can get with .045" shims under the shaft. Shim kit from Mancini. The shaft still needs to go up more, and the roller tip is way off to the exhaust side. There is no way to get the roller to sit in the center of the valve stem, and maintain square at 1/2 valve lift, by raising or even lowering the shaft.

This pic is at max lift

 

[Paul_G]

And, If I use a lash cap, the shaft will have to go up even higher, the same amount the lash cap raised off of the valve stem. Is that right? Using a .060" lash cap, I need to raise the rocker shaft .060" too?

 

[wyrmrider]

Hi paul
you can see from the angles that the higher you go the closer the tip will get to the shaft
what's your sweep when set at half lift ignoring where the roller is on the tip
you know what the answer is- you have to move the shafts up and back
but let's see the stripe first
are you watching rumble?

 

[Paul_G]

The stripe. It does not change much. Always rides on the exhaust side of the valve tip. Yes, up and back. Up gets the rocker square with the valve stem, back puts the roller in the middle of the valve stem tip once we have achieved square. We can shim the rocker shaft up, but, we have no way I know to move the shaft back or toward the intake side to maintain square. That dimension must be built in to the rocker arm. If I keep going up with the rocker shaft the roller will eventually ride the middle of the valve tip, but we will no longer be square.

It seems like the only thing I can do to use these poorly designed and expensive rocker arms is to put a .060" lash cap, and get a B3 rocker shaft shim made about .095" or more.

 

[Paul_G]

I am really sorry to expose my ignorance on this issue and bring all of you with me. I am by no means an engine builder and never will be. What I am is a retired instrument and electrical technician who worked in an industrial environment for 40+ years. I learned the importance of getting things right, or your destined to keep fighting the same battles with the machine. On top of that I am a little **** with how things are, compared to how they are supposed to be.

Another thing. Rotating the cam to max lift with different lengths of pushrod/adjuster screw exposed under the lifter, the total valve lift was less with more adjuster screw being exposed. As much as .015" less.

So what did I learn? Use the longest push rod possible to expose the least amount of adjuster screw that will allow proper oiling of the push rod cup. Or it will be stealing valve lift. Thank you to who ever suggested doing that.

 

[wyrmrider]

More than you want to know
https://www.speed-talk.com/forum/viewtopic.php?f=1&t=8650
Just work with B3
lash caps optional but they do protect the stem and give some retainer clerance
idk about .061 let us know if you find any
but does not matter as long as B3 knows

 

[steve340]

I think your rocker shaft needs to go down relative to the valve tip. Try the lash caps with no shims.

 

[wyrmrider]

let's see how that works out
just the opposite of Crane's "quick lift" excuse

 

[Paul_G]

I think your rocker shaft needs to go down relative to the valve tip. Try the lash caps with no shims.

When measuring for square at 1/2 lift it tells you which way the shaft needs to go, up or down. In the pics you can see my line across the rocker, center line between the roller tip and fulcrum. The roller tip is higher than the rocker shaft. The shaft needs to go up to get the 90° angle between the valve stem, or spring retainer which I am using to measure the valve side, and rocker arm.

Top pic shows roller tip on stem at max lift
Center pic is checking square at 1/2 lift
Bottom pic shows roller tip on the valve stem at 1/2 lift

 

[IQ52]

You cannot make the geometry correct with those stupid Mancini shims before you run out of/off of the valve tip. And you can make it worse with lash caps and lowering the rocker shaft. Run what you have and you will have no problems with your cam. Or you can make it better by working with B3RE!!!!

 

[wyrmrider]

Exxactly what IQ52 says
do not fret about "loosing" some lift by not overadjusting the pushrod
chevy guys been making that mistake for years
when you get the most lift you have the rocker perpendicular (90 degrees) near max lift- that's where you get the max ratio,
but it throws off the camgrinders plan for going over the nose - making float more likely, requiring stronger springs

AS I said just the opposite of Cranes mickey mouse "quick lift" so called theory where the 90 was near valve closed
bottom Line is Crane screwed up on the design of their early rockers and needed a cover story to sell them
Quick lift is also quick close and valve crash
now how does that work out.
I guess you could make either absurdity work with a cam that matched the absurdity, if it could be ground
but why when you are trying to be mechanically efficient and max area under the curve.
Don't talk to me about short rod blah blah blah have to get lift quick blah blah blah, reversion b b b
ok end rant
Thank Iq

 

[Paul_G]

You cannot make the geometry correct with those stupid Mancini shims before you run out of/off of the valve tip. And you can make it worse with lash caps and lowering the rocker shaft. Run what you have and you will have no problems with your cam. Or you can make it better by working with B3RE!!!!

The Mancini shims have issues. They were just used to verify what happens when raising the rocker shaft. Those shims do not seat well between the shaft and pedestal. I can only imagine how much oil will leak past the shim and never get in to the rocker shaft.

 

[Wietse]

Ordinary shims do not do the trick.
See how the B3 kit moved my rocker shaft, up and away from the valve.
See the contact pattern before and after.

Micheal from B3 is a helpful guy and will set you up with a kit to get it right.
He will send you a sheet to complete some measurements.
A side note is, that you must be prepare to elongate the bolt holes of the rocker shaft to give space for it to move off-center.

 

[Paul_G]

Ordinary shims do not do the trick.
See how the B3 kit moved my rocker shaft, up and away from the valve.
See the contact pattern before and after.

Micheal from B3 is a helpful guy and will set you up with a kit to get it right.
He will send you a sheet to complete some measurements.
A side note is, that you must be prepare to elongate the bolt holes of the rocker shaft to give space for it to move off-center.

View attachment 914800 View attachment 914801 View attachment 914802 View attachment 914803 View attachment 914804

Those are nice! I sent the measurements back to Michael. Lets see what he thinks.

 

[beanhead]

Harland sharp rockers don't necessarily 'suck', but on these big block Mopars they almost always have to be relocated up and away from the valve stem. B3 will make the proper spacers to get you all set up. One thing to note here... It does require enlarging the mounting holes in your rocker shafts. B3 will do that for you (recommended) or you can do it yourself with a burr, but it's messy and noisy! Kind of a pain if you don't do that stuff all the time

 

[wyrmrider]

remember that IQ said you could just run them
mild cam and not a lot of lift
but then you do not need them at all
but since you have them...

 

[Wietse]

As Beanhead mentioned, Michael can also do the bolt hole elongation for you.
I did it myself as i do not have the easy option to send them to him. (actually he could have supplied a new set, machine them and send all together...but that is talking too late)
Sending them in is what i would have done when being on that side of the pond.

but since you have them...

Indeed, but people need to be aware of this requirement before swapping to roller rockers on these Mopars.
As far as i've seen there is not a single vendor mentioning this that when converting to roller rockers that a geometry correction is required.
Probably will scare a lot of customers away from buying them i guess.

 

[Paul_G]

What really irritates me is that I paid $1000 for these rocker arms that are supposedly built to fit Edelbrock and Trick Flow heads, and they are not right, and require hundreds more $$ to make them right. There are much less expensive rocker arms to purchase if you are willing to accept them being not right.

 

[threewood]

The rocker shaft hole elongation is quick and easy with a dremel.