Crude Intentions

iTrader: (1)

My question also joe is it workmanship/craftsmanship or maybe improper application? Maybe something in the cam spec causing more of an impact or hard ramp or quick drop off?

MILD THUNDER

iTrader: (3)

Certainly could be any one of those issues.

I don't know exactly what caused my crane rocker to split the trunnion in half. Being that it was old as hell, I doubt it was a "craftsmanship" issue. Either fatigued, or something else.

Not being an engineer, I can only speculate. When I see that companies like Crower, and comp, have huge trunnions in their steel rockers. Crane came out with the larger trunnions in their "wide body" lifters. I assume, that was a case where, they either saw a need to do so, as in applications where guys where running the wide bodys, or steel rockers, they also were running some good spring pressures.

We have come a long way , from the days of flat tappet 120/310 spring pressures, and 400hp engines. Today, we are seeing 500+ lbs of spring pressures, and much more horsepower. Think of how much more cylinder pressure there is to open the exhaust valve against when you're running a blown 454 making 800hp, vs a NA one making 400hp. Thats more stress on the cam, the lifter, the rocker, etc.

MILD THUNDER

iTrader: (3)

Mike Tkach, was that rocker that broke, on the exhaust ? Did it break the fulcrum, or the rocker body?

I know that motor had to be making some good steam being a 565 with a procharger

mike tkach

iTrader: (3)

it was an intake,kind of strange.the body broke on the bottom near the trunion.that caused the pushrod to slightly bend.a new rocker&pushrod and he was running the crap out of it again.

Crude Intentions

iTrader: (1)

All good info. I decided to go ahead and measure. The shaft for the trunion is .55 and center on center is 1.6.

getrdunn

iTrader: (7)

I think I mentioned earlier I've always used crane golds and never had any issues. I never did ask edeavour32 where his broke a while back. If I didn't already have crane golds I would most like get the comps. Then again until heads are strapped on and pushrods are in place who's to say what I will end up with.

MILD THUNDER

iTrader: (3)

I will say, i did like the the finish on the scorpions better than the cranes

mike tkach

iTrader: (3)

joe,my guess is your crane gold broke due to it,s age,no rocker arm will last for ever.i think the scorpian that broke on the pro charged 565 is the first and more will break.we are asking a lot from them.i see a steel body arm in this engines future.

MILD THUNDER

iTrader: (3)

My thoughts as well Mike T

mike tkach

iTrader: (3)

you stated that you formed your opinion a long time ago on the scorpion rocker arm.would you please tell us what made your mind up on them.