The reason you measure things

[GSTOY]

So I'm getting ready to check for proper pushrod length, and I thought I'd measure my new Comp Cams pushrods. You will see in the picture, the pushrods are all 8.225, but in reality, they measure anywhere from 8.234 to 8.246....no wonder why they are clickity, they are all over the place. Just thought I'd share my findings. And yes, it' calibrated and I did zero it.

Steve

 

[DailyDrifter]

Wow, Thats quality control at its finest You do have adjustable rockers right?

 

[pacecarta]

you are aware that pushrods are measured at the outer edge of the ball that contacts the recess of the lifter ..not overall length from tip of ball

 

[GSTOY]

Straight from Comp Cams website, interesting reading, I learned something new today....How to measure pushrods...

Measuring the length of a pushrod is really rather simple, but it can be confusing at times. The most important thing to remember is that different manufacturers measure pushrods differently. So not all pushrods of a stated length will measure exactly the same. The three most common pushrod measurements are shown in Diagram B on the next page.

Theoretical Length: This assumes that the pushrod has no oil hole in the end of it. Therefore, the radius at either end is complete, which lengthens the pushrod approximately .017" in the case of a 5/16" pushrod with .100" diameter oil holes, minimally chamfered.

Actual Length: This is what you would measure if you had a set of calipers large enough to measure over the oil holes at each end of the pushrod. This is the measurement that most people can relate to. Unfortunately, this measurement is affected not only by the diameter of the oil holes, but also by the entrance chamfer for each oil hole.

Gauge Length: Although the most difficult to measure (it requires a special length checking gauge part #4997), this measurement is the most reliable. This is because the oil holes and their chamfers are eliminated from the measurement. The only problem is that not all companies use the same gauge diameter. COMP Cams® uses a .140" gauge diameter. All of the Magnum and Hi-Tech custom length pushrods listed on pages 270-275 of this catalog are measured using this technique. See Diagram B on the following page.

So since I don't have the special length checking tool, but I do have a dial caliper that is long enough to check the entire pushrod, let's use theoretical length. In my case as I stated above in my first post, if you use actual length, which is not perfered, I had actual lengths between 8.234 and 8.246, but if we add the .017 as stated above to get theoretical length, we now have lengths of 8.241 and 8.253, and my pushrods are supposed to be 8.225?....could this be another reason why the comp cams roller setups are noisy because valve preload is not set properly?

Looking above, we have between .016 and .028 differences in length just in the pushrods from theoretical measurement to stated measurement on the pushrod. Now if you are trying to achieve .035 valve preload, you could actually be tighter than what you thought. Could this be a reason for collasped lifters?

 

[pacecarta]

as you copied ..comp uses a .140 diameter cup so they are on the ball which has a fixed diameter as opposed to a hole wich can be flattened a little in processing , you would need a hole .140 in both ends of your measuring tool to measure properly ,doing it this way the length stamped on the rod will be less than then the overall length you measured with a caliper

if you used an adjustable checking rod tool as comp instucts to do and sent it in your rods would come back the same lentgh as your tool was so that would eliminate preload error
.01-.02 wouldnt have much effect on a hydraulic lifter , on a solid lifter thats another story if you dont have adjustable valve train but i cant see anyone doing solid with out some type of adjustable rocker

 

[Mad_Trbo]

Interesting and I see your point if you have a non adjustable rocker arm. What are you using?

I have to admit I historically had no noise issue with my comp cam 885's, but I also had adjustable T&D arms. Recently I think a lifter failed all together at least that is what I think happened. The lifter would not pump up, I can't get verification on that so that is what I am saying has happened. I've got new lifters on the way.

If pushrod length is the issue it doesn't say much for that nice post we have for the Morrel lifters.

 

[GSTOY]

Unfortunetly, I had already ordered the comps before the morels came out, so I'm going to give them a try. So far, they all pump up and stay that way. Heck I barely hit the oil pump with my drill, and I get some great shooters. It will be interesting to see if I get the same shooters in the morning after everything has sat overnight. I've also done the Earl Brown oil mods to the front cover.

I really spent some time making sure the lifters were clean and then I used my oil can to push oil thru them before I've installed them. I guess time will tell to see if they hold up.