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Old 01-30-2013, 12:40 PM
MouseFink MouseFink is offline
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A 350 CI Chevrolet using 1.65:1 aluminum full roller rocker arms (I assume the rockers are for a Chevrolet)

It appears to me that your poly-lock adjustment nuts are running out of rocker stud adjustment threads before you can set the valve lash. (?)

ARP offers rocker studs in several different effective lengths and Smith Brothers offer custom push rods in any length you need to correct valve train geometry. Camshafts can be ground up to .460" valve lift and use stock equipment. When valve lifts get above .460", cam grinders will grind the camshafts with a smaller base circles so the cam will fit through the cam bearings. .

Is your spring height set at 1.700"?
Taller valve spring heights will require longer push rods and rocker studs with a longer effective length and in extreme cases over 1.800", taller valve covers.

It is a solid lifter camshaft?
The solid lifter (flat tappet or roller) push rod seat can be as much as .200" deeper than a hydraulic lifter push rod seat and the cam lobe base circle of a aftermarket camshaft with more than .460" valve lift may be as much as .070" smaller in diameter, requiring a push rod that is .035" longer. Example: Smith Brothers (or equal) custom push rods that are nominally 7.435" long (.200" push rod + .035" base circle + 7.200" standard SBC push rod length = 7.435").

Before you order custom push rods, use an adjustable Comp Cams (or equal) push rod and a light weight spring to hold the valve closed. Then you can check the rocker/valve tip contact pattern which should be centered in the valve tip at 1/2 valve lift. If it is a solid lifter camshaft, it will require precise push rod length to set the valve lash. Hydraulic lifter pre-load can vary as much as +/- .060" and are more forgiving when calculating push rod lengths.

What brand and part number are the rocker studs?
If your rocker stud effective length is too short and are runnign out of adjustment threads, you will need rocker studs that have a longer effective stud length and more adjustment thread length. ARP has them in various lengths. The most common studs used for full roller rockers on a SBC is ARP 134-7104. Those studs have 1.895" effective length, 1.00" adjustment thread length and 7/16"- 14 base threads. If you are using stock screw-in rocker studs, you must use stock rocker nuts and do not use full roller rocker arms. Poly locks use 3/8-24 Class 3 threads and stock studs are 3/8"-24 Class 2 threads.

Last edited by MouseFink; 01-30-2013 at 12:50 PM.
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