earlymopar wrote: ↑Sat Jun 18, 2022 9:36 am
The .100" valve tip height increase equates to less than 4 degrees of rocker angle change and negligible change to the contact area location on the valve tip.
You are wrong. You have three relationships that determine geometry. The height of the valve stem, the position of the shaft and the amount of lift. There is four if you are adding a roller tip to the rocker but you didn’t do that so we won’t consider it here.
When Chrysler established the position of the shafts relative to the height of the valve stem and the amount of lift, they did al the math and put them where they did because it was correct for that stem height and lift.
You can not alter any part of that three part equation and not change the geometry. It doesn’t matter what name is on the valve cover, if it has shaft rockers it’s all the same.
What you have done is added .100 to the stem length. That is MASSIVE. You MUST correct the placement of the shafts to correct the geometry. That is the ONLY fix.
Plus, I’m going to ASSume you are running more lift than stock, so that affects your geometry as well.
In your case, the shafts have to go UP and AWAY from the valves. You can’t just raise the shafts, because it will run the rockers into the springs.
There are only two ways to do this IF you have shafts that sit in a saddle. The Poly doesn’t have that so you have only one way to correct geometry.
If you have saddles, you can call Mike at B3 Racing Engines and give him some numbers and he will machines up a set of spacers that raise the shafts and move the shafts away from the valves. You have to elongate the holes in the shafts so the bolts don’t stop the shafts from moving away from the valves.
The other way is to mill the stands down and machine or buy a set of blocks and and adjust the shaft height with the thickness of the blocks. You will have to do it this way because the Poly head doesn’t have saddles.
You will need to make or buy some blocks and move the shafts up and away from the valves. How far up and away I can’t say. You have to do some math to figure it out. You also have the issue head bolts going through the stands you already have so you’ll need to deal with that.
In my opinion your best, cheapest option is to call Mike at B3 Racing Engines and talk to him about how to address moving the shafts on a Poly head. I’d bet everything I have that he already has a system developed to allow you to move the shafts and keep the head bolt holes where they go.
There is no other way to fix this than relocating the shafts.
And as I said, if you add a roller wheel to the rocker that also affects geometry.
