Scorpion Roller rockers Cracked!? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 08-05-2009, 03:57 PM
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Scorpion Roller rockers Cracked!?

I built a chevy 355 last year and put it in my truck. It's a 1989 block, 2 bolt mains, had it bored .030 over, new cam bearings, freeze plugs, etc etc. and I bought new EQ lightning CC180BA heads for it. I put in hyperutectic pistons, comp cams ~.5"lift int/exh. Stock Chevy Hydraulic Roller lifters. I bought a brand new set of 1.5 Scorpion Full Roller rockers. I ran the engine for maybe a total of 10 hours before taking it down again to replace a leaking pan seal. I took the heads apart to make sure everything was fine with it and two of the Rocker arms have hairline cracks at the roller tip where they roll on the valves. I don't know what could cause this. To put them in, all I did was put them on the studs then screw the nut on while the particular valve was closed, while twisting the pushrods back/forth until I felt resistance, then went a half-turn past this, then tightened the setscrew. Any ideas??
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Old 08-05-2009, 04:45 PM
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Quote:
Originally Posted by awoodman
I built a chevy 355 last year and put it in my truck. It's a 1989 block, 2 bolt mains, had it bored .030 over, new cam bearings, freeze plugs, etc etc. and I bought new EQ lightning CC180BA heads for it. I put in hyperutectic pistons, comp cams ~.5"lift int/exh. Stock Chevy Hydraulic Roller lifters. I bought a brand new set of 1.5 Scorpion Full Roller rockers. I ran the engine for maybe a total of 10 hours before taking it down again to replace a leaking pan seal. I took the heads apart to make sure everything was fine with it and two of the Rocker arms have hairline cracks at the roller tip where they roll on the valves. I don't know what could cause this. To put them in, all I did was put them on the studs then screw the nut on while the particular valve was closed, while twisting the pushrods back/forth until I felt resistance, then went a half-turn past this, then tightened the setscrew. Any ideas??
Not uncommon with low price aluminum rockers. Probably tracks back to improper or inadequate heat treatment in the manufacturing process. Take 'em back, use the money for a down payment on a set of stainless Comps.

Bogie
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Old 08-05-2009, 04:52 PM
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you think they'll take these back? im guessing they'll just say that it's my fault for not properly adjusting valves. I bought them through machinist awhile ago.
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Old 08-05-2009, 05:02 PM
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Quote:
Originally Posted by awoodman
you think they'll take these back? im guessing they'll just say that it's my fault for not properly adjusting valves. I bought them through machinist awhile ago.
I'd give it a try the worst they'll say is no.

Sure they'll say it's your fault, they always do and often the user is at fault. But your description of setting them sounds mighty good to me. Besides, the kind of failure you're talking about isn't what you get with set up, it is caused by either inadequate strength in the material or over revving the engine which places more load on the rocker ends than they are designed for. I'm working from the position that this is a fairly common failure but not seen by all your rockers which strikes me as a heat treat error, though it could be the trunnion or the rollers have excess clearance which causes a small but hard bang in the rocker bore. Another could be the trunnion shaft bore is too small for the shaft and the rocker cracked when the pin was pressed in.

Bogie
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Old 08-05-2009, 06:00 PM
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That reminds me when I got my block back from my machinist. A 1998 Vortec 350. I didn`t want to have it bored so he said he would hone it for me. He mic`d it, it came out at 4.001. He said after honing it might be at .003, still within limits. Since He had did so much work for me in the past I agreed. I got the block back and like a fool I didn`t check the bore. Only after I heard the pistons knocking and it smoked like no tomorrow because the rings wouldn`t seal did I learn the block was 4.009.
Had I checked it I would have knew not to build it. Lesson learned. Always check behind another`s work.
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Old 08-05-2009, 06:39 PM
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Scorpion rockers are a very high quality piece made right here in America (Florida) and carry a lifetime guarantee to the original purchaser, and advertised as good for over .800" lift and 1000 psi open spring pressure. If the machinist you bought them from won't deal with you, you may have to deal with Scorpion directly, and I've heard they have good customer service. I've used Scorpions three times now, they are like jewelry compared to most others including Comp, Crane, and Harland Sharpe, and IMO the only step up from them would be the Comp or Crower steel bodied or a shaft system.
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Old 08-06-2009, 02:25 PM
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i called, they said send them in and they'll send me a brand new set. very nice people, awesome customer service
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