The length of a pushrod will depend on a variety of factors: the base circle of the camshaft (higher lift cams with reground smaller diameter base circles will require longer pushrods) and the height and location of the lifters; whether the pushrod cups in the lifters are offset or centered; the location of the pushrod cups or adjuster screws in the rocker arms; the geometry of the rocker arms and rocker arm ratio; the installed height of the valves; and how much the cylinder heads or block have been milled.
With so many variables, it's important to get the correct length pushrods so the tips of the rockers will be properly positioned on the tops of the valve stems. If the pushrods are too short, the rocker arms may exert a side thrust against the valve stems as they push the valve open. This can increase friction, valve stem and guide wear, and increase the risk of valve stem breakage. If the pushrods are too long, the valve spring coils may bottom out and bind at maximum valve lift, causing damage to the valvetrain (typically a bent pushrod).
Most professional engine builders know how to measure pushrod length, and how to determine the correct length pushrod for a given camshaft, cylinder head and valvetrain combination. Adjustable length pushrods are available to make the job relatively easy, assuming you know where and how to measure.
To determine the right length, an adjustable pushrod is installed in the engine. The length of the pushrod is then adjusted so the roller on the end of the rocker arm is over the exact center of the valve stem when the rocker arm is at the halfway point of its maximum lift. It's also important to make sure all the valve stems are installed at the same height so the same length pushrod can be used for every cylinder. If valve heights vary, each pushrod will have to be measured individually for each valve.
With pushrods that have balls at both ends, the length can be the overall length of the pushrod end-to-end, or it can be the "theoretical length" of the pushrod (which is measured as if the oil holes were not in the balls). Determining the theoretical length requires using a special gauge that compensates for the oil hole, or estimating how much the oil hole reduces the radius at each end of the pushrod.
With pushrods that have a cup at the top end, the overall length can be measured end-to-end, or you can use the "effective length" which is the overall length of the pushrod minus the depth of the cup on the one end. This can be done by placing a ball in the cup, measuring the overall length of the pushrod with the ball in place, then subtracting the diameter of the ball.
Whatever method you use, make sure your pushrod supplier knows how you are measuring pushrod length so you can get the correct length pushrods from them. You may also need to discuss spring pressure and rocker arm ratio to determine how much stiffness is needed to handle the load.
You asked for a yes/no answer so I gave you one. For some it will work and for others it wont. Just like Burger King stated in his stolen post. If the heads are milled, or different cam or rockers MIGHT make enough difference to need new push rods.lame..... lol
wythors: thanks man!!
Way to plagarize there. http://www.enginebuildermag.com/Article/1481/push_rods__lifters.aspx
The stock pushrods worked just fine with my combo. Click the link in my sig for complete details.
yea, so? does it matter where it came from? its good information so i gave it.
If no one ever repeated anything someone else told them (this goes for text also) no one would ever know anything.
It's generally in good taste to quote your sources, rather than cutting and pasting it and passing it off as your own.
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