408 hyd roller, too much spring pressure?
I’m bold enough to say it. 99.999999999999% of the time when a rocker and a spring hit the geometry I wrong. Simple as that. It’s not bold. It’s a fact.
It's not a fact. It's a foolish statement. I'm not even going to argue with you about it, I'm simply going to point you to an engine build and a T&D article which both address this very issue. You can argue with those guys:
620hp SBM
How To Build A Pump-Gas 620hp Small-Block Mopar - Car Craft Magazine
Frequently Asked Questions - T&D Machine Products
WHY ARE PLUS RETAINERS OR KEEPERS ARE AN ISSUE?
When a cylinder head is assembled with the correct spring, retainer and keeper the tip of the valve protrudes past the top of the retainer. If a plus retainer and/or keeper is used, the valve tip becomes recessed in the retainer. The rocker arm will contact the retainer prior to the roller contacting the valve. To make the roller contact the valve tip, clearance must be cut into the rocker and can cause the rocker to break prematurely.
In the past we have seen and heard of some customers raising the stand to clear the spring, unfortunately this sacrifices geometry for clearance and can now lead to guide wear issues. The best fix for this issue is to eliminate the plus retainer and/or keeper or add a lash cap.
WHY ARE BIG SPRINGS AND LOW RATIOS A BAD COMBINATION? (DRAWING)
This is typically an issue with the small block Chevy, Ford and Mopar engines.
When a large diameter spring is used with a “low“ ratio rocker arm, it can create a clearance issue between the pushrod and the cylinder head. The large spring requires a longer rocker to keep proper clearances. The longer rocker requires the adjuster to be further away from the fulcrum, increasing the overall length of the rocker even more.
Some people machine the rocker arm for clearance, but this is NOT anything we recommend.
WHY ARE MAXIMUM SPRING DIAMETERS SPECIFIED?
Spring diameter is a big factor mainly on small block Chevs, Fords and Mopars. Many engine builders stick with a relatively low ratio rocker arm and make up the lift with the cam lobe. The rocker arm itself is short so that if a 1.50 thru 1.60 ratio is used there is pushrod clearance. Because this rocker arm is “short” there is a limitation on the spring diameter that can be used. For 1.450” fulcrum length rockers the maximum spring diameter is a 1.550”. If the geometry is correct, the rocker will have plenty of clearance to the spring and retainer. If a 1.450” long rocker is hitting a 1.550” diameter spring and retainer combo, the usual reasons are the stand is too low or a plus height keeper or retainer have been used to increase installed height.
