212 hemi

what is the max lift a hemi head can take without touching the top of the piston relief..... was thinking of getting a .310 cam with some 1.2 rockers and some 26lbs springs those that sounds right for a little drag motor?
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Lift has little to do with valve clearance during overlap. Duration and lobe center determine how far the valve is open near TDC. When valve is at max lift it is nowhere near the piston. Exhaust is the more critical one as the piston is chasing the closing exhaust valve and if there is any float they could collide. I just build a hemi with a BM jr and .310 lift and 1 to 1 rockers it has no clearance issues but with 1.2 to 1 rockers you need to check. I used 37 lb springs cause the JR needs a bit more spring than the regular BM.


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Any work on the spring pockets for the 37# springs on the hemi head ? Just curious ... I thought that the hemi head would have issues with any thing more than a 275 lift cam and also that the spring pockets had to be widened for heavy springs
It is a black mamba jr but in his website you can get it with various lifts under the custom cam section, I got it as a 230 duration with .310 lift so I guess I am confusing people by saying it is a jr but it basically is with faster and higher lift ramps. For the 47 lb single springs I got from isky they are wider and require the spring pockets cut. I bought the cutter Isky sells then found it cut a 1 inch seat which was hitting some side protrusions in the head. I chucked it in the lathe and with a toolpost grinder narrowed the cutter from one inch to around .900 but I am going from memory and lately it is not too reliable.
If I had gone with the 246 degree duration and .310 lift I could have used 26 lb springs and not had the hassle of cutting the seat. When I did that motor the only ratio rockers for the hemi was brad hills (200$) and if figured it was easier and cheaper to just go hi lift. But the seat cutter cost $100 so maybe it was foolish economy. I also had to clearance the block slightly. Now NR and arc sell the i.2 roller rockers for 99 bucks.
The 310 lift and 230 duration requires more than 26 lb springs for higher rpm. The longer duratiom 246 degree cam and 310 lift works good with 26 lb springs.