Adj. Rockers & Push Rod Help

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R72Demon

R72Demon

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This is my first time using adjustable rockers. I have 273 factory adjustable rockers on a 340 with a MP .508" hydraulic cam. The first thing I did was replace the original adjusters on the rocker arms with crane cam ones with a jam nut. Next I ordered a push rod length checker. With the engine on TDC and the cam on its base circle, I used the push rod tool (with 2 threads showing on the adjusters) and came up with a total tip to tip length of 7.250. I had the push rods made and I just installed them. The rocker adjusters are backed all the way off and when I torque the rocker shafts down, 2 of the push rods are touching the bottom of the rockers. Is this normal because the cam is opening those 2 valves, or are my push rods too long??? Can I just rotate the engine over and adjust the lash on the base circle?
 

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When you tighten the rocker shaft only a few of the cam lobes are going to be on the base circle...some are going to be in the processes of opening and closing the valves...and a few might be on the nose of the cam...so just back off the adjusters but leave the ball of the rocker out a bit so the pushrod can engage it....

and then go thru your adjusting sequence of the rockers turning the engine over by hand....and the rockers will need to be screwed in to tighten up and preload the lifter..
 
If you originally measured the 7.250" length tip to tip, then that may be the general problem. It usually needs to be measured from the tip of the ball to the BOTTOM of the cup at the other end. This is called 'effective length'. If you measured to the TOP of the cup (tip to tip), then your measured length will be approximately .175-.185" longer than effective length.

Ball-cup pushrods ordered from tip-to-tip length may well end up too long as most manufacturers sell ball/cup pushrods to the effective length, not the overall tip-to-tip length. Whose pushrods did you purchase?

Otherwise, there will indeed be variations in initial pushrod positions due to lift. Each pushrod has to be set with the crank at a certain position. See here:
http://www.forabodiesonly.com/mopar/showthread.php?t=255277
 
The rocker adjusters are backed all the way off and when I torque the rocker shafts down, 2 of the push rods are touching the bottom of the rockers. Is this normal because the cam is opening those 2 valves, or are my push rods too long??? Can I just rotate the engine over and adjust the lash on the base circle?
Click to expand...


Yes it is normal and yes you need to rotate engine over and adjust all the rockers on the base circle of the cam.
 
If the cup is hitting the rocker arm then you have a problem. Pushrods are to long.
 
In the picture some pushrods are hitting the rocker cuz the lifters are on the cam lobes and the adjusters are backed off. rotate the engine and adjust each rocker when the lifter is down, zero slack plus a 1/2 turn
 
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