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#1
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Rocker Arms
HELLO, i have a set of 273 factory adj. arms on my 360.
my question is how much lift will these rocker arms handle ? as usual thanx for the replies OOPS. also valve spring pressure OHIO DEMON |
#2
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The rocker arms basically act as a fulcrum,so how much lift they will handle is really dictated by the strength of the pushrods and spring pressure.Generally,the cast iron rockers can handle a .500 lift cam safely,with moderate spring pressure.What cam and springs are you using??
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#3
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hi chris, i'm using a comp cams xtreme energy284/296 (240/246@.050) hydralic it has .510 lift 76degrees overlap.i'm also using hughes 1110 springs@310 lbs. pressure
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#4
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273 rockers are fine, i've used them on a 71 340 with a flat tappet camshaft with .560 lift and turned 11.20's @ 121 mph at 7200 rpm all day long. - rj
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#5
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Beaware that stock factory adjustable rocker arms can be way off on the ratio. They are supose to be 1.5, but in reality can be 1.25. So you may not be getting the lift you think you are.
They can be checked with a dial indicator if you want it to be right. Michael |
#6
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Those 273 rockers are forged, as opposed to the AAR rockers that are cast. It is the diameter of the valve that gets ugly at high lifts. The use of valve lash caps helps in this aspect. I dont know if the rockers can be that far off from each other, but it is a fact that they can be matched.
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#7
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273 Rockers
I don't think the ratio is as bad as 1.25:1. I used them on my 340 with the MP 284°/.528" cam and I got .475" lift at the valve with .028" valve lash. So there was about .025" lost in the valvetrain geometry somewhere. I suspect much of that is in the lifter/pushrod angle. That's why the new R3/R4 blocks use the 48° lifter angle vs. the 59° in the production blocks. That's a leftover from the polysphere da
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#8
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I'm gonna add, worst case senerio 1.25 ratio. It's just one of those things you check if your looking for the maximum power.
I'm sure there are some rockers that are over the ratio, we check for that too, cuz then I would be illegal. Michael |
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