breaking rocker arms

[Walline]

I have a SBC with protopline al. heads. I am running a solid roller with .675 intake, .630 exhaust. I have broke 3 rocker arms, this year. I am using jegs roller rockers, (was told they are fine up to .800 lift) This same combo was fine last year. The only change is different springs, this time they have a dampner. Cam grinder had me run these. When inspecting I noticed the valve retainers have touched the rocker at two different spots. When the valve is on the seat, and at full lift , i have about .040 clearance. I am wonding if I am bouncing the valves, or getting deflection in the studs. Surely the rockers would not be junk after 2 seasons, with very few passes on them. Any ideas, would be great. Thanks everyone!!

[CNC BLOCKS]

I have a SBC with protopline al. heads. I am running a solid roller with .675 intake, .630 exhaust. I have broke 3 rocker arms, this year. I am using jegs roller rockers, (was told they are fine up to .800 lift) This same combo was fine last year. The only change is different springs, this time they have a dampner. Cam grinder had me run these. When inspecting I noticed the valve retainers have touched the rocker at two different spots. When the valve is on the seat, and at full lift , i have about .040 clearance. I am wonding if I am bouncing the valves, or getting deflection in the studs. Surely the rockers would not be junk after 2 seasons, with very few passes on them. Any ideas, would be great. Thanks everyone!!

We build a lot of circle track engines and where the rules don't allow shaft rockers we have always used the Crower Stainless rockers for years with no problems as we have seen other competitors try to run the Aluminum rockers and we have seen failuars in that area. Just one thing make sure your not in COIL BIND. And go to a STUD GIRDLE USING ALUMINUM HEADS

In the long run you really don't save any money ruuning the cheap rockers as I am sure you WILL have more rocker breakage before your done.

[BigPurp]

Where are the rockers breaking? Blowig the roller up, spliting the body @ the trunion etc. I've seen quite a few different AL rocker setups that require "clearancing" around larger valve springs.

What ratio rocker?
What is the seat and open pressure on the springs?
Cam specs?
Have you checked to be sure your not getting into coil bind when the motor warms up?

[Walline]

They are 1.5 ratio. they have 220lbs, on the seat. I am sure they are not going into coil bind. One broke the bottom out of the bodyand the other two broke the trunion. Cam is ADV 297, 300 on a 112. I do think I need stud girdles. Not much meat on pro heads!(raised runner)I will try and post a picture, of the two spots where the retainer has rubbed the arm.

[BigPurp]

If your blowing the bottom out of the body it's time for an upgrade. It very well could be that the spring rate combined with the ramp on the cam is just over stressing the AL rocker. The new Crower rockers are awesome, they changed the oiling feed so they bleed out the tip now, and don't spray all over so you can adjust them with the motor running

Or just make the right move (rules permitting) and get some Jesel or T&D's Expensive but one more thing you'll never have to worry about ever again.

[ALKYBURNER]

In my opinion just buy a set of jesel, td or even a set from wild wilferd his are far better than the two mentioned before but again they are more expensive but guess what no breakage. The old saying pay me know or pay me latter your choice.