Roller Cam pushrods?

[blackgn231]

I got a set from Champion Heads that are .0850 is this to long? I am not that great at checking this and need some advice from someone who has done this to there car,I am running stock heads that have been milled only to get a clean suface ,anyone I was told about marking the center of the rocker arm back to the spring and turning the motor over one complete turn and if they are right they should end up in the center of the spring retainer is this true or am I misunder standing this anyone ?

[blackgn231]

They are 8.250 5/16 .120 wall

[Powder]

I'm not an expert either but I'll share what I've learned while working on my current 4.1 build. The length of the pushrod is determined by lifter preload which on my comp cam kit from full throttle should be .020-.040". You check this by marking the push rod at two different positions and measure the distance between the marks. This is explained in more detail in the installation instructions from Comp cams that came with the kit. The pushrods in my kit were 8.225" long X5\16diam. X .080 wall thickness.
Also, if your cam has a lift of .510" or more your exhaust valve guides need to be modified so you can use a positive type seal that also requires replacing the stock style exhaust valve. I've read comments that this isn't really necessary if you just stay with the stock exhaust valve setup but people like turbofabricator and my machinist strongly recommend machining the valve guide and adding a seal with a new aftermarket style valve. I did it.
MLH

[BlackBandit]

The ONLY way to get the correct length pushrod is to assemble the block/heads (gaskets in place and torqued) and measure. If you do anything but that you're just guessing.

["More Boost"]

summitt racing sells push rod checker's (adjustable) for like $12. just get one in the 7.5" to 8.5" range or so. real easy to do and u will have piece of mind.

[Just a Six??]

Originally Posted by BlackBandit

The ONLY way to get the correct length pushrod is to assemble the block/heads (gaskets in place and torqued) and measure. If you do anything but that you're just guessing.

Exactly! You need proper length for preload & correct geometry for oiling. DONT GUESS!! Get the tool for $12 & do it right!

[tyroneveee6]

i have adjustable pushrods and they suck

[blackgn231]

I got a dial indicator and my push rods should have been 8.250 at least thats what the box said but they came out to 2.840 are push rods off this much normally I its only a 1000 but what gives? This push rod thing is driving me nuts I read the way to do it from Comp cams about marking the push rod but its black so how do you mark it? Am using a adjustable one now ,Have been told to adjust it till it just starts pushing the lifter cup and stop pull it and add 40 thousands to that for the preload.

[BlackBandit]

Originally Posted by blackgn231

I got a dial indicator and my push rods should have been 8.250 at least thats what the box said but they came out to 2.840 are push rods off this much normally I its only a 1000 but what gives? This push rod thing is driving me nuts I read the way to do it from Comp cams about marking the push rod but its black so how do you mark it? Am using a adjustable one now ,Have been told to adjust it till it just starts pushing the lifter cup and stop pull it and add 40 thousands to that for the preload.

I don't really understand your numbers there. A dial indicator is something you would use to measure movement. Do you mean caliper? Either way what do you mean when you say the came out to "2.840" and "it's only 1000"?

If you have an adjustable just make sure the pushrod you're measuring for has the lifter on the base circle. Then stick it in there and adjust it out until it's snug. You don't want the valve or the lifter plunger to move. Lock the pushrod, remove it, and measure it. Write down the measurement and do the next one. When you have all of them done look at your measurements. If they are pretty close get a set of pushrods that puts the preload at about .040" on at many as possible. It's ok to have a little leeway here. The nice thing about a hydraulic cam is you don't have to be exact on every one. HTH james