I need to measure my pushrod length so i can buy new pushrods for my engine build. I have a hydraulic roller cam with roller rockers. I have a comp cams length checker. Do i want to soak my lifters in oil before i do this, or should they be dry? I saw a video that said when it comes time to set the rocker pre-load, that it's better to have the lifters dry. But, i haven't found anything about filled or dry lifters for pushrod length checking.

 

If you're using lightweight checking springs like you're suppose to then it doesn't matter if the lifters are filled or dry. The lightweight springs won't be heavy enough to collapse the plunger in the lifter but are more than strong enough to hold the valves closed.

If you're checking for pushrod length with normal valve springs in the head then use solid lifters. If valve spring pressure is too great, the adjustable checking pushrods will bend.

 

I have regular springs in the heads. Are you saying the lifters should be filled or are you saying i need to buy a set of solid lifters in order to check the pushrod lengths? I'm not worried about the length checking tool bending because it's made from the same alloy steel that the real rods are made from.

 

THIMK:

When doing this measurement, you want the push rod to be living in the same environment that it will be living in when the engine is running.

So, at that time, what state are the lifters in?

Right.

Since you have the regular valve springs installed, they will certainly overpower the springs inside the lifters. Therefore, you can somewhat hack your way around it by using empty lifters, measuring the "ideal" push rod length by minimizing the "sweep" WITHOUT ANY REGARD WHATSOEVER for where the pattern lands on the valve stem, measuring the lifter plunger travel, then subtracting about half of the plunger travel from your push rod selection.

 

I ordered a set of comp cams light weight checking springs, but the plungers in the lifters are still depressing. Are the lifters worn out? Do i need new ones? If i need new ones is it OK to use them with a used cam?

 

Take two lifters apart, temporarily remove the guts and stuff the lifter bodies with 5/16" nuts and you've basically built a solid lifter that will allow you to finish your pushrod measurement. That's what I did, I am using the LS7 lifters. IIRC 3 nuts filled the lifter body perfectly. Just be sure to take those nuts out and reassemble your lifters correctly.

 

I was under the impression that these checking springs would prevent the lifter plungers from being depressed. How did you account for preload when using the nuts, or did you not preload the rocker arms?

 

Is it possible to replace them with solid roller lifters?

 

Checking springs worked fine in my case with the new LS7 lifters, and they did not collapse. The reason I had to put the nuts in my lifters was because I was also checking the piston to valve clearance using the "clay" method (because I didn't have a degree wheel at the time and didn't want to do a lot of math). I suggest nuts in your lifters because I thought I read that your lifters were still collapsing with your checking springs. I would not say this indicates any condition (worn or OK) of your lifters since the oil is really what does all the work when the engine is running, but there are more lifter knowledgeable people on here than I am.
As for preload, I did preload my lifters by 3/4 of a turn on the rocker studs. Because this is such a small amount, and I was not going to order custom made/custom length pushrods, the little amount of pushrod length that it changed with that preload was not enough to push me to the next length up or down on a pushrod.

 

Checking springs can still collapse a lifter. Dont need to soak hyd rollers just need to lube the wheels and bearings well before install.

Best way is to do what Lurbie said. Stock lifter gutted and filled with small washers/nuts and reassembled to be a solid.

 

Thanks guys. I will try this out.

 

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What kind of lifters do you have?
If you have a retro roller, that is a link-bar type, then you can't take them apart to gut them. The rivets that hold the link bar prevent the plunger from being removed.
If you have an OEM roller or a typical flat tappet then taking them apart and stacking with washers is the way to go. Then you can use the springs you intend to use in the build. If you decide to use a solid lifter as replacement then it's ESENTIAL that you use one with the same cup height as the one you're replacing. Otherwise your measurments will be off by the difference in the cup height.
While not super critical, using the intended valve spring (or just the outer spring if a dual or triple) will ensure that the tolerances are completely taken up. A checking spring can introduce some slop in the assembly and give an inaccurate measurement.

 

I have the OE style lifters. Also, is it necessary to check pushrod length for every valve?

 

With your OE lifters, a spare can be turned into a solid so you're good to go there. If you want to get really precise, leave a gap in the stack up that corresponds to the amount of preload you intend to run.
As for every valve, well...yes and no.
It's advised that at the very least you check one intake and one exhaust. Now, the yes and no part comes from problems associated with casting and machining tolerances. While it's not likely you'll catch an oddball cylinder or valve that takes a pushrod that's .050" longer than the others to achieve the smallest sweep (and best placement) it has happened.
A mild or pedestrian build may not need to go this degree of accuracy however when you get to the extreme end of high performance valve trains and lobe design, it's easy enough to burn out a set of guides in short order.
Be sure you're using the rockers you intend to use for the final assembly. Those, along with changes in cylinder heads, valves, block deck, head gasket and of course the lifter will affect the overall valve train geometry (VGT).