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Ductile Iron Rockers

727

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I picked up a set of used Ductile iron adjustable rockers for a Mopar Big Block. Everything about them looks like a crane rocker arm. (minus the name crane cast into the bottom. Does anyone know who mfg these arms? Also,
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is there a quick way to tell if they are 1.5 or 1.6 without installing them on an engine?
 
I have a set of Iskys and they say that. Erson, Crane and most if not all have the name cast in. Yours might be factory original or dealer. The pad surface looks kind of beat up but should be able to be repaired and bushed. I dont think anyone makes these any more. 1.5 or 1.6 ?? You should be able to measure from the adjuster to the tip. I dont know the spec but it is out there.
 
Isky's have& Crane's have the name. Don't recall about Erson's. Been a while, but I'm pretty sure the factory versions had no markings. My 1.5 ratio Isky's are 1.5" tfrom rocker shaft CL to valve tip center & 1" from shaft CL to pushrod ball center. As for ratio of yours, measure them. Factory would be likely be 1.5 ratio.
 
These were Ersons. When comparing them to the 1.5 Cranes that I used, they had more lift. So they must have been 1.6

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I enlarged one pic. And added your pic. Look very similar and mine had no name either.
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Isky's have a hardened pad for valve contact and the name cast into them. Crane have no pad but also have the name cast into them. My guess is there are factory original adjustable rockers. I had a set a long time ago.
 
Isky's have& Crane's have the name. Don't recall about Erson's. Been a while, but I'm pretty sure the factory versions had no markings. My 1.5 ratio Isky's are 1.5" tfrom rocker shaft CL to valve tip center & 1" from shaft CL to pushrod ball center. As for ratio of yours, measure them. Factory would be likely be 1.5 ratio.
Makes sense Thanks
 
Edumacate me here guys, but what big-blocks (besides the hemi) came from the factory with adjustable rockers?
 
Early big bocks. They also had seperate aluminum shaft pedestals instead of the cast ones of the later heads. So those motors would have been 413's, 426 wedges, and possibly early low deck big blocks.
 
Thanks for the information everyone?
What causes Galling on these rockers and how much lift is advisable?
 
They're probably good to .600 lift at the valve.

Galling is usually caused by using crappy stock shafts and not changing oil regularly.

Most galling is caused by the friction of "similar" metals, that's why many things have bronze bushings. It has more to do with bronze being a dissimilar metal than its lubricating or friction properties. In the case of the rockers, they're iron and the shafts are steel - dissimilar enough to work without galling PROVIDED they are kept well lubricated and have no binding. But once one starts to gall it'll just get worse. Using good thicker polished aftermarket shafts goes a long way to prevent galling. TRW used to make good replacements at a reasonable price and were rumored to add 10 HP just because they were more rigid !!
 
Max Wedges used them, not sure about the non HP versions. Also available thru DC in the mid - late '70's.

Galling comes from not pre-lubing a fresh or long dormant motor & big high pressure valve springs.
 
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What would be the easiest way to tell a big block from a small block ductile iron rocker?
 
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