Spoke to Sheldon earlier.

He said "where'd it break, about the second thread of the adjuster?" Yep.

He didn't have too much input on life span. Said 700 runs is a lot, but they go longer. Said if they're fatigued usually an exhaust breaks first. As we know it all depends.

So I said how long for new ones? He said for some spares or a whole set? I said both. 8-10 weeks for one or two spares, 20 weeks for a whole set.

Luckily I have some (used) spares. It is strange to me that the rockers themselves don't have part numbers stamped on them. I just emailed to get the individual part number for the rockers used in the set (PN 3130 for the whole set). I'm assuming the rockers themselves are the same used on other heads with different stands but don't know for sure, I only know that they're different than the rockers on our spare engine which has Dart Pro 1 355s. I would assume they'd have as few different rocker bodies as possible and use them with different stand setups for different heads but I don't know. Maybe I'll get lucky and find a dealer with a few on the shelf.

Probably will order a couple new ones then order a new set later in the season since this engine is due to be freshened in the off season anyway. If I order a new set now they won't be here till about the end of the season anyway. Hopefully they survive. If not I'll plug our spare engine in and she keeps racing (it was the wife's car that broke it).

TonyB, Sheldon has said the same to me previously. I don't have the LSM tool, rather a custom made similar one. I'm not a gorilla that overtorques them. Same thing with the rocker shaft to stand bolts - apparently people stretch/break them all the time. 20# is plenty! Tech, they're dated 2014 which is when we built this engine.

I had the best luck on my set. Well over 1000 runs at the time I sold them. No significant ware. Mind you I ran a mild spring, titanium valves, but did have 1.8:1 on the intake. Far better than Jessel Pro and before that Crane shaft rockers.

quote:

Originally posted by 183N:
Broke an aluminum T&D intake rocker yesterday. 1.8 ratio, approximately 700 1/4 mile runs on it, .858 lift cam turning 7700 making appx 1000 HP.

First issue I’ve ever had with a rocker arm. Replaced it and the car ran the same, nothing else caused it that I can tell. What kind of life do you expect from them? Should I be looking at replacing the whole set? Going to call them tomorrow figured I’d see what the group thinks.

What size push rod are you running.

quote:

Originally posted by TonyB6255:
I'm not saying this is OP's issue but one of the things that many people do when running valves is over torquing. This came straight from Sheldon at T&D.
Do yourself a favor and get the LSM valve Lash tool. It comes preset at 22 lbs and it so easy to use.

Over torquing is not the issue. The problem is that in most cases where you run big lift camshafts, you have allot of spring seat pressure and a massive amount of open pressure and of course everybody runs a .080 wall 3/8 push rod. At high RPM that push rod is like a wet noodle and the valve train is out of control. I`ve seen broken valve springs, retainers that i need a sledge hammer to get the keys out, broken roller wheels, material pounded out between the seat ring and head and of course broken rockers. Anything i build, the spring is spec`d out to what the valves weigh and something like a .850 lift cam will get a tapper .165 wall, 1/2 to 9/16 push rod. It sounds like over kill but one of the things you cannot have enough of in an engine is push rod diameter. In my personal engine i run 5/8 diameter and they are 13 inches long. If most of the guys running this typical set up were to put their engine on a spintron, You would see allot of issues with the push rod you`re trying to run.

quote:

Originally posted by 434 olds:

quote:

Originally posted by TonyB6255:
I'm not saying this is OP's issue but one of the things that many people do when running valves is over torquing. This came straight from Sheldon at T&D.
Do yourself a favor and get the LSM valve Lash tool. It comes preset at 22 lbs and it so easy to use.

Over torquing is not the issue. The problem is that in most cases where you run big lift camshafts, you have allot of spring seat pressure and a massive amount of open pressure and of course everybody runs a .080 wall 3/8 push rod. At high RPM that push rod is like a wet noodle and the valve train is out of control. I`ve seen broken valve springs, retainers that i need a sledge hammer to get the keys out, broken roller wheels, material pounded out between the seat ring and head and of course broken rockers. Anything i build, the spring is spec`d out to what the valves weigh and something like a .850 lift cam will get a tapper .165 wall, 1/2 to 9/16 push rod. It sounds like over kill but one of the things you cannot have enough of in an engine is push rod diameter. In my personal engine i run 5/8 diameter and they are 13 inches long. If most of the guys running this typical set up were to put their engine on a spintron, You would see allot of issues with the push rod you`re trying to run.

Good point on push rods,,, there are two buts here though, we aren't talking prostock cams and spring pressures and your typical ported BBC conventional head will never fit a 1/2" diameter pushrod without breaking through, nor is that diameter needed. In addition push rod diameter required is not just determined by the loads they will see, the length also plays a key role,,, sound like your deal has PR's about 4" longer than a typical BBC. There is no reason a 7/16" diameter PR with the appropriate wall thickness won't work in this application.

BTW, in certain applications, PR are intentionally chosen to be flexible!!

7/16” push rods in it.

Our 540 with Dart Pro 1s has 3/8” push rods. Not sure if we can open them up enough for 7/16. The 3/8” definitely flex.

Or just order the right chit the first time, instead of tripping over dollars to save dimes.

Steel rocker arms

Patience is a virtue

Top38 is 100% correct on both push rod size and length. When I made plans to build my current blower motor I ordered a .400 raised cam with the 10.2 block to keep from having long push rods. Also went with a 55MM cam core. Chose 1/2 inch Manton push rods on the exhaust side because of exhaust valve opening against boost. With the 174x Profiler heads I spent hours with a die grinder and blue dykem clearancing the push rods and this is after Reher Morrison ran a CNC push rod clearance program on the heads. I had thought I ordered steel exhaust rockers but received aluminum and decided to use them and not wait for steel. Like I said in a earlier post, except when I had an issue early on with some rocker and stand bolts the came loose and causing some destruction I have had really good luck with them.
I would also like to mention that Darin Morgan at RM originally set up these heads and after the damage he highly recommended welding the intake and exh stands together, I had actually broke the intake stand in 2, he said in boosted application there is allot of flex in the stand. So once I had the geometry was correct I torqued the stands to the heads and brought the heads to Darin and he tig welded them together on the heads so basically I have a 1 piece stand now.

Pushrod diameter is application specific. Tracy Dennis built my 900HP 522/532 that has made thousands of passes seeing 8100rpm in the lights. It had 3/8” .080 wall pushrods. Some will argue that they were flexing and my reply is maybe but what they weren’t doing is breaking.

Food for thought - when they rip the adjuster end off it's usually due to a torque issue on adjustment.

When they pull apart at the shaft bearing it's due to cycles. Runs are really over rated on aluminum. It really has to do with heat cycles. For example a bracket car doubled could put 10-15 runs on the engine while never really cooling down. (1 heat cycle) A super comp car could make 2 runs in a day and it would have 2 heat cycles.

Also - steel rocker have there own issues. Keep an eye on things as harmonics have now cam into play with them that aluminum use to absorb.

SL...

quote:

Originally posted by DragRaceResults:
Food for thought - when they rip the adjuster end off it's usually due to a torque issue on adjustment.

When they pull apart at the shaft bearing it's due to cycles. Runs are really over rated on aluminum. It really has to do with heat cycles. For example a bracket car doubled could put 10-15 runs on the engine while never really cooling down. (1 heat cycle) A super comp car could make 2 runs in a day and it would have 2 heat cycles.

Also - steel rocker have there own issues. Keep an eye on things as harmonics have now cam into play with them that aluminum use to absorb.

SL...

Scott

With regards to your statement on heat cycles vs runs,,, maybe, I would say the amount of load has much more to due with fatigue than heat cycles. I have seen rockers that are as old as dirt still running fine, lots of heat cycles there. Without a doubt, the higher you stress a part the sooner it will fatigue and visa versa. Steel rockers on boosted and heavy NOS motors are an added safety factor that I would not overlook vs the potential harmonic issues for sure in these motors. Way to much potential damage if an ex rocker breaks at WOT!!! As with anything, pick your poison.

Top I don't disagree with high cylinder pressure applications for steel. That just got dragged in to the initial post.

It's the egg and chicken theory otherwise and I think for normal applications heat cycles are much more damaging then total runs which he was asking about.

Rockers are kind of like aluminum rods. You just got to put a number on them and live with it.

SL...

One other thing. Anyone ever buy an aluminum bat for baseball or softball? They have disclaimers on not using them below 55 degrees! Anyone start their engines below 55 degrees?

Just say'n

quote:

Originally posted by DragRaceResults:
Top I don't disagree with high cylinder pressure applications for steel. That just got dragged in to the initial post.

It's the egg and chicken theory otherwise and I think for normal applications heat cycles are much more damaging then total runs which he was asking about.

Rockers are kind of like aluminum rods. You just got to put a number on them and live with it.

SL...

I guess the chicken egg theory is always there. The only question is the number! And let's not forget the materials and heat treat process over the years of production all adding up to more chickens and eggs.

I will say this for sure, heat cycles on electronics is definitely a real factor!