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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?
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Originally Posted by I.C.U.Lookin
(Post 4519669)
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?
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. |
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 |
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.
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All good info. I decided to go ahead and measure. The shaft for the trunion is .55 and center on center is 1.6.
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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.
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I will say, i did like the the finish on the scorpions better than the cranes
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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.
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My thoughts as well Mike T
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Originally Posted by offshorexcursion
(Post 4519550)
Nothing, I've formed my opinion a long time ago but like many am waiting to post or not going to post for some reason.......:party-smiley-004:
If you reread my post though I'm referring to his specific build, not just scorpion rockers in general. A. Interesting tech discussion during these slow times B. Showing genuine interest in a fellow members projects. C. Without knowing his build specs how can we properly recommend a product |
Originally Posted by mike tkach
(Post 4519720)
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.
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I had Erson junk rockers on my old engines thats what one engine had when I got them, the other had PBM rockers, no issues, them Erson looked like complete junk made in a garage, but never issues, I think most issues are unstable valvetrain or setup.. I might be wrong though...
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I put Scorpions in my 28 Elim with hydraulic roller setup. I still talk to the guy I sold to. No problems yet at all. That was 5 years ago. 200+hrs
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Originally Posted by MILD THUNDER
(Post 4519610)
Last year, when I was rocker arm shopping, the Crane Gold rockers, were MIA. Everywhere. Nobody had them in stock. Apparently, production on them stopped, and rumor was, they were being outsourced. I always liked the cranes, but obviosly, if you cant get them, then that does no good. I then began really liking the option of a steel rocker arm.
One of the things I've seen , on some aluminum rockers, including my old Crane Golds, was the Trunnions split in two. The Trunnions on the steel rockers, like the Comps, or Crowers, are massive in comparison. I chose to go with the new Comp Ultra XD magnum rockers, based on some info I had got on them. Basically, they were a new and improved design, that alot of technology went in to. Lifetime guarantee against breakage is a nice feature as well. They must feel pretty confident in them to offer that. Another option they offer on them, is an upgraded Trunnion, if you were to decide to run 1/2" diameter rocker studs, instead of 7/16. We all know steel has a much better fatigue life, and the weight savings isn't there when comparing to an aluminum rocker. Basically, I saw no benefit to the aluminum rockers over them, or the Crowers. I simply chose the Ultra XD rockers, based on the fact they were 100 bucks or so less than the Crowers, and they were something new. I like new stuff to try. Mark |
Originally Posted by MrCIG
(Post 4521892)
Joe are those Ultra XD's made in the USA? I will probably replace my Crane Gold rockers as a couple have some play in them that I don't like
Mark http://www.compcams.com/ultrapromagnum/ http://www.chevyhardcore.com/tech-st...asters-degree/ https://www.youtube.com/watch?v=UrWK73ysF3Y |
Originally Posted by MILD THUNDER
(Post 4521926)
I do not know where they are made Mark. The Crane Golds used to be made in USA, but I do not think they are anymore. The Scorpion rockers are made in USA.
http://www.compcams.com/ultrapromagnum/ http://www.chevyhardcore.com/tech-st...asters-degree/ https://www.youtube.com/watch?v=UrWK73ysF3Y That's pretty amazing lifetime warranty. Although I've always had great success with crane golds I know what I will be using in any future builds. What a nice piece. |
Originally Posted by getrdunn
(Post 4521936)
That's pretty amazing lifetime warranty. Although I've always had great success with crane golds I know what I will be using in any future builds. What a nice piece.
I talked to too many people/engine builders that had Scorpion breakage the past few years, and that ruled those out for me. |
Originally Posted by MILD THUNDER
(Post 4521940)
That was my thoughts as well. I was trying to find a set of new crane 1.7 rockers with the TR fulcrums, but nobody had them in stock, anywhere. I decided to look into other options, and thats when I found these, and began looking into them.
I talked to too many people/engine builders that had Scorpion breakage the past few years, and that ruled those out for me. |
https://cimg5.ibsrv.net/gimg/www.off...20837515af.jpg
Less than 100 Hrs Crane Gold --- HA Not taking any chances again I am gong with Jesel Shaft Rockers |
has it been hitting on the valve cover ?
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Hitting something that’s for sure.... |
No didn’t hit anything it was just a piece is shi$ it had porosity in the aluminum at the top half if rocker the bottom of it was a clean break QUOTE=Full Force;4648672] Hitting something that’s for sure.... [/QUOTE] |
Were those new? I was told that the C-# was the date code. C-04 would be 2004. It looks like a mixed set, I could be wrong.
Also, I've seen Jesel aluminum look like that. Aluminum has a finite life in this application. |
Rockers are a great app for steel imo |
My engine builder is always telling me to go for Jesel but they are so expensive, you do you think ? Are they worth all that money |
I had a set of Harland Sharp shaft rockers that broke the same way. After I did some research and found out it was a common problem with them. They had low hours on a street car, less than 500 with most at 2100rpm or less. They did inspect the set and replaced the broken rocker. This was a $1200 set. I never bolted them back on the heads. I tried to save a few bucks over a set of T&Ds. Cost me more money in the long run. I am running the T&Ds now for 10 years without any problems at all. I just sent them back to T&D for inspection as I am rebuilding and upgrading the engine. The rockers all were in great condition. They recommended changing the roller tips so I did.
There is always time and money to do it right there second time. Just my .02 |
You might consider the Crower stainless
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I just recently used 3 sets of scorpions, 2 on iron 880 heads and 1 on edelbrock rect ports. I was able to get perfect geometry on the iron heads, on the edelbrocks it was sketchy and far from perfect no matter how long or short i adjusted the checking pushrods. I would have tried something else to see if i could get it more ideal but customer bought them and was set on running them no matter what, i got the geometry the best it was going to be and callled it good,fwiw, Smitty
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