Broken studs: Pushrods too long??

That's funny about the Straub video. It's the very one I used to follow my measurement. In fact I emailed Scott with a few questions at the time, and he got back to me.  Very informative and helpful. 

shootist wrote: I would also suggest (if you haven't already) that you use a micrometer to measure the actual pushrod length. It is very possible that the wrong length pushrods were put in the wrong box by the manufacturer. Or if the pushrods were ordered by someone checked then returned they could have returned them in the wrong box.

I would have said that as well, but if they are bent, then the reading would be off.

After some thing like that, I would verify all are straight before thinking of doing anything with them.

Good point on the spring tolerances with preloaded, but I thought Eddys allowed for bigger than stock spring setups. Just was not sure how much more than stock until it was verified .6000.

This is a job for Boris... post your spring rate, measured lift, and spring gap at lift measured, and spring gap limit by the spring manufacturer, rocker arm ratio, and your factory cam lift once more in a nice spec listing for him to notice.

I still think them 3/8" studs may not be the best option for your setup. As wear may show push rod length being a causé, but if your springs and loads on the studs cause rocking under revs then you will get wear as well.

Harmonics and flex under pressure will cause them straight rocker studs to bend in and out as if springy, and make for some interesting wear as well as break.

I am not an engine builder, but am cautious about some things that can be over looked by the obvious. I have plans to run a hydraulic roller cam, and am set for 7/16" studs. So i don't have to worry about the excessive forces on the studs.

You did not say you run a girdle maybe instead of changing to 7/16" studs, add a girdle, it may be the best cost effective option for keeping your 3/8" studs inline.

Hi All,

Just an update, as promised. I did check the length of my existing pushrods to confirm they were the length I ordered (as shootist suggested). The were dead on.
In remeasuring everything last night, using the Scott Foxwell/Straub method of checking valve train geometry and pushrod length (see earlier post above with a link to a youtube video). All this done again last night and rechecked, looks like my pushrods are nearly 0.100" too long.

Running it through the engine cycle by hand using the adjustable pushrod in place at the new shorter length, looks like I have much better clearance of the poly lock to the inside top of the rocker slot and the pushrod-to-rocker clearance near the bottom backside of the rocker. As well, the roller tip is near dead center of the valve tip...and certainly the "sweep" of the tip across the valve stem is minimal. All good (better).

I'm ordering new pushrods and rocker studs today.

I think that might take care of my rocker stud failure issue. Many thanks for all your input.

Cheers.
Steeno.