I've also been advised to have the roller on the valve tip only move in "one direction." IE the roller moves across the valve tip towards the exhaust side when opening, and rolls back to the inside when closing the valve
Ultimately, I took the easy road. Used the "recommended" parts and talked to someone smarter than me. Mike @ B3 Racing Engines
I guess the roller is only reversing direction once per cycle instead of twice. I have no idea what this does to the dynamics of rollers and oiling.
I read their page,
B3 Racing Mopar rocker arm geometry and their spacers do look very thick, which is what my measurements seem to say I need if I'm going to use roller rockers. Do all roller rockers require such thick shims to make things right? I'll try and throw out everything I've heard, and reread their tech guide.
I'm not building this motor. It started as a five speed install, and things got out of hand with while I'm at it, then cleaning the motor, then changing cam and intake, and everything snowballing, lol.
You didn’t say what heads you are using so I’ll just make general statements here. If you read Mike’s tech pages you should have had this cleared up in your mind because it’s rather simple to understand but more complicated to achieve.
Any shaft system, ANY shaft system is the same. The relationship between the centerline of the shaft, the tip of the valve and the amount of lift must be engineered into the original location of the shaft. And the designed rocker arm geometry itself changes things. You can make a 1.5 ratio rocker several different lengths and each one will change the geometry if you start swapping them out. It’s as simple as that.
Any one of those parameters you change, or all of them means you OUGHT to correct your geometry. It’s that simple. So let’s say you buy some Trick Flow heads and TF established the geometry using brand X rockers and you use brand L rockers the probability is the geometry will be wrong. Valve stem height is critical. Let’s say with the above heads you want to make an upgrade and you decide you need to use .100 long rockers you have now affected the relationship between the tip of the valve and the centerline of the shaft.
It used to be the only way to correct this properly was to mill the rocker stands down and use blocks to get the geometry in shape. Mike’s‘ shims are by FAR a easier, simpler and cheaper than using blocks. And they work.
How many times have you seen engines where the rocker and the retainer hit with relatively small diameter springs? I see it all the time. And the number one response is put a beehive spring on it. Can you do that? Sure. Is it correct? Not even close. You didn’t fix the core issue, you just used a band aid where you really needed an amputation.
I can tell you for a certain fact if you change any one of the above parts of your valve train as in going away from whatever the OE design criteria was you’ll certainly need to correct your geometry. Start changing more than one of those criteria and you will have issues. You’ll be down on power. Your valve train will be unstable. You will lose RPM capability. And you’ll fail parts. The number one killer of rocker arms (outside of cheap junk) is bad geometry.
Invariably, the shafts will need to go up and away from the valves. It’s worth every penny to measure your particular set up and then see how much correction you need. I think you’d be surprised how much you’ll need.
