I have broken two roller rockers now. One each at back to back races. Split them where they get thin as they start to wrap around the shaft. Is it wise to say that the whole set is equally fatiqued, and I should replace them all as soon as I can? Any rockers tougher than others? Stock diameter shaft with a bushing. How many 1/4 passes is anyone getting out of a set?

Mike

As a reference, I run the old style Isky #384 chilled iron rockers with a Lunati roller and kit, .707/.711 lift. #225 seat pressure. This is on a 427 HR engine.

I get around 150 runs on a set of rockers before they generate a split that initiates at the oil lube hole for the ball and cup. Close to or at the first sign of failure, I change out the whole set as they will domino. You can catch the start as the lash will change slightly.

I ran the Isky's on a Lunati .612/.619 flat tappet and they will run forever. With the flat tappet I ran Harlan Sharp shafts.

When I went with the roller, I upgraded to the Dove end stand supports which necessitate the use of their shaft, which is slightly longer.

I have a new set of HS roller rockers, just never installed them. Maybe one day, I will.

Regards,
Dennis

What year will # 150 come Dennis?

Back in the day when things were simpler, I was at the track every weekend, an easy ten runs.

Now I can be optimistic and say they could last forever.

One of these days I'll dust off the blue car.

Regards,
Dennis

Who's brand of rocker was it ??? If it was one of mine, let me know. If not maybe consider mine. About 4 months ago started a design change that will add .050" to the underside of the Rockers. I also change the radius' to get as much metal as posible. The new ones will be done next week. This should eliminate any problems with mine. Here is a picture of the new vs old.

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Doug aka pumpbldr
Precision Oil Pumps

The only other thing i'd suggest is if there a way to get a thinner bushing? The ones i've broken have always split between the bottom of the pushrod notch and the shaft. That's only with the big roller valvesprings, the solid cam won't break them.

Mine are the first design, bought from Ford Power Parts in the mid 80's but several have been changed over the years and the newer ones are noticably improved. My roller application might be a severe case since the valvesprings are 800lbs open , 1.625" diameter and a two inch installed height which puts the retainer height flush with the valve tip. I've had to notch the rockers a bit for the edge of the retainers.

The adustment never changes when i've checked them, they oil fine and don't gall pushrods and with no restrictors they don't flood the valve covers.