Pattern on Valve Tip Opinion
 

Hi everyone, we are measuring pushrod length today, we made a hydraulic lifter solid by stacking it with washer, we then turned the engine until lifter was on back side of lobe, adjusted stock factory length pushrod to zero lash, tightened the poly lock, then turned the engine two full revolutions and this is the pattern we got. Looks awful wide to me, but we have never measured pushrod length using factory stamped steel rockers like this build will use, its always been full roller rockers in our past builds. Is this pattern normal for a stamped steel rocker? If so, how does it look? Heads are factory 6x4, just barely cleaned up to make sure they were flat, no more than .010" taken off deck, stock length 4.98" Ferra valves, Crower 68404 springs are set up at 1.550". Camshaft is a Voodoo 704.

For got to mentioned above, we will be ordering the .116" wall pushrods from Butler just as soon as we know for sure the length we need. We were just using the factory length pushrod to initially measure it with for a starting point.

Did you look up the Straub method to set your pushrod length?

I did, but the method they show is using a full roller rocker, which is next to impossible to figure out when using a stock stamped style rocker, do to no Trunion and roller wheel axle centerline to go off of.

Stamped steel rockers do swipe a bit wider than a roller tip variety but I've never had any quite that wide.

Did you vary your adjustable pushrod in both directions to see if it tightened up the pattern some?.....

Thanks Cliff, we haven't tried the adjustable pushrod yet, we just did it with a factory pushrod first to see where it was at, and this was the result. We will check it with the adjustable pushrod and report back.

Here is the pattern with the adjustable pushrod at 9.200"

Looks you need a longer pushrod from your first post. Not the second.

Try this:

Set the lifter on the base circle of the cam. Now set the adjustable pushrod in place and adjust the rocker until there is zero lash. Now lightly rub the rocker across the valve tip to establish a witness mark on the valve tip. Inspect the position of the mark and re-adjust the pushrod length until the witness mark is roughly 1/3rd of the distance toward the intake side from centerline.

Another reference, about 2/3 of peak lift the mark should be about center of the valve tip.

I hope you had the tops of the valve guides topped for positive seals because this is a picture of the not enough retainer to guide clearance you will have at only .500” lift without the guides topped.

This shown is with a stock length exh valve and a stock retainer like I see your using, and this is on a 6X head also.

Thanks Steve, we built the heads, and took some off the retainers and cut the guides down for Positive seals, so we made sure everything had plenty of clearance when we put them together. All of them have atleast .060" retainers to seal clearance. Thanks for the heads up though, much appreciated!

👍...

Here is what it looks like the the pushrod adjusted to 9.100"

Here is the witness mark with the lifter on the base circle, lifter at zero lash, pushrod adjusted to 9.100"

Witness Mark with lifter on base circle, lifter at zero lash, pushrod adjusted to 9.150"

Witness Mark with lifter on base circle, lifter at zero lash, adjustable pushrod set at 9.200"

The pattern is wide even when you are not moving the rocker across the lift range. :)
That explains much.

Here are the two witness marks, one on the base circle, the other at 2/3 lift, both with the lifter adjusted to zero lash, and the pushrod adjusted at 9.200"... to me, the 9.200" pushrod seems to be the best so far. What do yall think?

Ok, we tried one more time, this time with the pushrod adjusted to 9.250". These ARE two different marks, one with lifter on the base circle, the other mark is at 2/3 lift. Lifter was set at Zero Lash(No Lifter Preload) for both.

So, reviewing and comparing all of my above pictures, am I correct in thinking that it seems that it may like the 9.200" pushrod the best, especially since .050" or so of lifter Preload still has to be added? The 9.200" witness mark above, at 2/3 lift, appears to be just a tad towards the exhaust side from the center of the valve, so I'm thinking by the time the lifter gets .050" or so of preload, it will be right in the ball park?

With the photos above, I'd agree.
I think it was post 7.. full sweep of 9.2 . Getting closer than I'd like to exhaust side of valve tip.
I'm curious how 9.15 full sweep might look compared.

I do like where the 9.2 begins

Thanks Pastry, I just edited my post above (#19) while you were posting a reply, just incase you missed it

We will do the full sweep with the 9.150" and report back in just a few minutes

Ok, here is full sweep with the 9.150" pushrod and 1 full turn of the engine. Lifter at zero lash.

Post 23 looks like about as good as you'll get.

Edit.. maybe 9.2 is better,, looks more narrow IMO.

Here is the witness marks, one on the base circle, one at 2/3 lift, both with the lifter at Zero Lash, at 9.150".

I was thinking by the time a person preloads the lifter .050" or so, the 9.200" may end up being the best, although the witness mark on the 9.150 is pretty centered, but that is WITHOUT any lifter preload too. I am by far not an expert though, that's why I need help LOL

Are your factory rockers new or used and can you post up a pic of the contact face on them.
Would be interested to see the diff in radius of the contact area on the stamped rocker, Vs the radius of a common roller tip rocker

We are checking with the factory rockers, but they are in excellent condition. We will be using New Comp Cams replacement 1251-16 though, which are exact specification as the stock rocker that we are measuring with. We are still awaiting delivery of the new rockers, so we are measuring with the stock rocker, but since they are identical specs, there should be no difference between the two as far as pushrod length. I don't have any pictures of the stamped rocker contact face at this time, but I can get a picture this evening.

I would wait till new rockers are in hand the new face at the tip might make pushrod checking easier due to a new surface

Different rockers locate their pushrod seat differently. Aftermarket rocker ratios will differ slightly, stamped steel ratio will differ more.

I'd also wait for the new rockers.

^^^ x2 on this ^^^

ALL rocker ratios vary slightly from manufacturer to manufacturer and style to style.

Since you are going to all this trouble to get an optimum-length pushrod, make certain that it is optimum with your NEW rockers.

Thanks guys!, as far as what I have measured so far(with the current stock rockers), what length do you guys favor the most? I was leaning towards the 9.200" by the time a person figures in .050" or so of lifter Preload. We will definitely check it with the new rockers when we get them.

I vote for the 9.200”.

While you have some time it would be interesting to cycle thru all of those stock rockers on that one valve just to see how much the ratio veries.

Ok guys, we got the new rockers today, and remeasured using the adjustable pushrod at 9.200". To me, the witness marks look even better with the new rockers, and I think the 9.200" is the winner. One mark is on the basecircle, the other is at 2/3 lift, both with the lifter at ZERO lash. By the time a person figures in .050" of lash, I think the 9.200" will be as close as we can get. We also measured with it at 9.150" appreas to be a little too short.

Looks good.

Thanks! I'm gonna go ahead and place my order at Butlers for the 9.200" .116" wall. I appreciate all of your help very much.