All,
I have had just finished putting the heads back on my car after it got a little warm and stuck a valve (turns out the machine shop where a little tight with their clearences on the guides...engine got warm, valve stuck etc etc)
Anyway I have noticed that when I put my rocker arms on the tip of the roller is all the way towards the exhaust side, barely on the valve stem. Now I know this is NOT good, do I need shorter pushrods?
I have a XE274 cam,lifters, aluminum body roller rockers (stock ratio), comp cams springs in a 69 small block. I have no history if the heads have ever been skimmed, but the intake seems to fit right.
I have a picture of one of the valves/rockers if someone could post for me...this is really frustrating me now.


Cheers
Nick

 

Yes,if your pattern is towards the exhaust, installing shorter pushrods will move you to the center. Best to get an adjustable pushrod to figure out exactly what you want.
Also,when going shorter your adustment nuts will travel closer to the bottom of the rocker arm stud threads. You do not want to get too close to the bottom or you risk wiping out the studs threads.
I had an instance with Trick Flow heads and stamped rockers in which I could not center the rocker arms without bottoming out the nuts. I had to go with their recomendation of .10 longer which placed me off center towards the exhaust. LOL
Bob

 

Like desertvette said, you'll need to get an adjustable pushrod to check the length you need. Once you've determined the proper length, check it using this method before you order them.
With engine @ TDC #1 fireing position, remove #1 rocker arm. Wipe the tip of the valve stem clean of oil and blacken the tip (where the rocker sits) with a permanent black marker. Install the rocker with push rod and adjust lash. Now turn the motor over by hand a few times. Return the motor back to original position and remove the rocker. If your push rod is the proper length, the rocker should have worn away the black mark righ down the center of that stem. If the mark is higher or lower, that will tell you if you need shorter or longer rods.
Good Luck
Eddie


[Modified by Silvr77, 5:09 PM 9/27/2003]

 

:nono: Yes Nick. Any time you change heads, camshaft & pushrods, deck block you to need to check pushrod length. The rocker tip needs to travel from the top 1/3 of valve stem tip to lower 1/3 area of valve stem tip. This prevents excessive side loading on the valve stem and early/premature valve guide wear. The side-to-side travel is limited by guide plates or stock casting slots and usually not a problem.
I tried using an adjustable pushrod (crane cams) to measure this for a full day while engine installed in car and gave up. I just couldn’t verify travel over valve stem reliably enough with the hydraulic lifters. I really think this is best done on engine stand.
Next tried a pushrod length checker tool from Proform. Very easy to use and cheap too. Since custom pushrods ain’t cheap I bought the same tool from Manley to verify and got a little different number – but not much.
Found Trick Flow chromemoly pushrod sets with assorted lengths at Summit for a great price. I think my pushrods where only about .050” off stock but the surprise was the set from Trick Flow measured only about .040” short though were even marked .050” short on each pushrod. Another discrepancy was that I was using 1.6 ratio rockers and neither Proform nor Manley tech assistance would answer this question/change for their checker application.
Anyways I finally bolted the valve train up, set the valves and now think my rocker tip travel looks good enough – using my calibrated eyeball. :yesnod: