Thread: Which rocker arms?

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So I busted a rocker Friday and I'm thinking now that one has failed others may be right behind it. I was using COMP Pro Magnum Steel full roller rockers... the one that failed busted what I guess you would call the steel trunion on the bottom that captivates the fulcrum roller...

Anyways I'm guessing the plain jane steel roller rockers just won't cut it... what should I use?

I'm running Lunati .630 mech roller cam with 250# on the seat and spin the motor up to (and maybe past) 7000 rpm.

Is there any weight penalty going to stainless or is extruded aluminum better... what are you guys running in your high revving big blocks?

Could this failure have occurred because I had the motor sitting for two months while I rewired the car and had too much pressure on the few valves that were open?

Thanks...

-Chris

i have used PBM / yellow terra .crane /lunati . scorpions/hoards. harland sharps. t@d . ss crowers i like them better then comps .i check them at mild lift so i know i get the right length push rods . all maker of rockers have dif geometry

Crowers have always been my favorites... Got 3 seasons on one set, still no problems.....

Thanks guys... good point on the geometry: Will I likely need to change push rods if I change out the rockers?

So stainless is best for durability? Are they not much heavier than aluminum?

Thanks for the suggestions... I'll do some more looking. Might not be something I get to this week but I'll feel better when I don't think another one is going to let loose.

Originally Posted by skids72

Thanks guys... good point on the geometry: Will I likely need to change push rods if I change out the rockers?

So stainless is best for durability? Are they not much heavier than aluminum?

Thanks for the suggestions... I'll do some more looking. Might not be something I get to this week but I'll feel better when I don't think another one is going to let loose.

some do not like ss rockers a alum rocker dampens better less hamonics ? the crower not heavy whatever you do check your push rods this is a big deal you need to check it with your rocker arm you going to use not some blue plastic $5.00 thing

thanks again, Pat

so aluminum may be better cause the ringing don't come through the valve train too much(?)... I'm just thinking about what is not going to break... yunno you break something and replace it with something stronger and find out what will break next

Sounds like swapping out rockers will be more than I should tackle for a race motor that needs to run hard soon... I was hoping it would be more straight forward but if I need to check/change push rod lengths I should leave it to the pros this time cuz I don't want to screw it up

I appreciate all the feedback...

-Chris

Originally Posted by skids72

thanks again, Pat

so aluminum may be better cause the ringing don't come through the valve train too much(?)... I'm just thinking about what is not going to break... yunno you break something and replace it with something stronger and find out what will break next

Sounds like swapping out rockers will be more than I should tackle for a race motor that needs to run hard soon... I was hoping it would be more straight forward but if I need to check/change push rod lengths I should leave it to the pros this time cuz I don't want to screw it up

I appreciate all the feedback...

-Chris

well you can check them with blueing on the valve stem roll over by hand should hit about middle of stem i do not do it this way but will work

roller tip should be a little on the outside of the center of stem fully closed and a little on the inside of center fully open, right?

I think I'll hold off on replacing them all for a while and just keep an eye out for any signs of cracking etc...

Thanks Pat and Dave for all the feedback...

-Chris

Opposite.....starts on the inside and travels outward or you'll wipe out the guides.

why are you running 250 on the seat of a 630 lift cam that you only want to turn 7000?

hey nitro... thanks for the clarification!

-Chris

Originally Posted by jerry clayton

why are you running 250 on the seat of a 630 lift cam that you only want to turn 7000?

hi jerry,

why not? Is this overly excessive? Motor was built to hold together to 7500 but doesn't pull much beyond 6800 in it's present configuration (I think this is mainly limited by the 280cc oval heads)... what does it take to keep the roller lifters on the lobes at these revs? I was under the impression the springs were kinda tame compared to some of my similarly equipped counterparts...

thanks,

-Chris

With today's faster ramp rates on camshafts just about everyone is going to 225 to 250 for a seat pressure on a BBC at least for bracket type cars.

i run that much on the seat it works and push rod lay out is right photo is like MR Nitro shows allmost middle to out side but like i said i check at mild lift with a ferry geometry checker

Yep--and broken rockers, pulled studs, extruded keepers/retainers, bent pushrods, busted lifters----
Bracket racing???? come on --half the time they are on a throttle stop

I only ran around 200 seat pressure on 800 + lift that saw 9500= several times