dyno 356 cam

#1
Putting a dyno 356 cam in predator hemi and just got through checking piston to valve clearance and came up with .070 on intake valve and .075 on exhaust valve. This is with stock valves and springs and lash caps with zero lash and no head gasket. Is this okay or too little or can i mill head .050 and put .010 head gasket on with .003 or so valve lash and still be okay ? ? Gonna still do mods on valves , springs and push rods but kinda worried about close tolerances on valve to piston clearance.
 
#2
I have run with as tight as .040 but any valve float and it is interference city. Recommended minimum is .080. Exhaust is most critical as piston is chasing valve on closing side.
 
#4
it is the exhaust that is critical intake would be fine but your exhaust would be at .055 if you over rev it the piston could hit the exhaust. With the hemi the valves are at an angle and it could bend the valve.
 
#6
That would be the fix get a stock intake of 25mm (or better a 27 if you have it, slot it with a dremel cut off wheel all around the circumference and make a cutter out of it, install it in the head put the head on with bolts finger tight and turn it with a drill for a short period of time and check to see if and how much it is cutting, only need it .030 deep on the exhaust.
 
#8
ole4 is giving perfect advise, as usual... You can cut valve reliefs with a die grinder if you have to..remember , the valve is at an angle.. and take your time. Too much clearance..no one will know..not enough clearance..everyone will know :)
 
#9
I was originally gonna put the dyno356 cam in a hemi predator and set the engine up for just that cam lift but i also bought a black mamba cam . Now i want to be able to run either cam and this is just for playing on a baja bike , no serious racing involved. so i was thinking about running the valve to piston tolerances close as possible and putting on different size head gaskets but keep everything in check as not blow the darn thing up !
 
#10
Hemi head mill

I like ole-4s idea about notching the piston. From what ive seen building compression on a hemi is a challenge, notching a piston seams like the far lesser of two evils compared to welding the head. The bottom line is its real nice to have more compression in these little motors for that extra snort.
Also your running a big cam so you what to help the low end. If it were me i would mill it and build it as tight as possible, id just notch the piston with a die grinder, a rouge measurement of a hemi piston (top thickness) i have came in at 0.160'' , not thick but a 0.030 notch should be no biggy.
That recommended 0.080'' i would take down to 0.020''. So your talkin milling 0.050'' but you could pull off 0.080''!!
 
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