Pushrod Measurement

[Pentroof]

Morel 5325 hydraulic roller lifters
Edelbrock heads, new and unmolested
new, stock non-adj rockers
pedestals shimmed up .060" for desired valve tip sweep

Comp Cams 7703-1 length checker (7.80" length + .050" for each turn)

Each measurement is zero lash with lifters on base circle of the lobes. Measured #1 at TDC firing, then rotated crank 90 and measured in pairs according to firiong order.

Is .065" total variation (high to low) too much too ask of a single pushrod length?

markings on the heads are:
(#turns out on checker tool)
(#turns x .050")
(total length = extension + 7.80" closed length)

[blykins]

Jim, I shot you an email back.

The jist of it is that you get the lifter on the heel of the lobe, use your adjustable pushrod and get to zero lash, then measure the length of it and add .050-.060" for lifter preload.

If you're running non-adjustable rocker arms, you will need a length checker with a 3/8" ball on one end and a 5/16" ball on the other. 

If you're not using calipers to measure the total length and you're just counting turns, that could account for some of your variation.  In addition, you have manufacturing tolerances in your valve job, valve length, rocker arm pad shape, etc. 

When you go to put the lifter on the heel of the lobe, use the EVO method:  check the intake pushrod when the exhaust valve on that cylinder is starting to open.  Check the exhaust pushrod when the intake valve on that cylinder is starting to close. 

[Pentroof]

I'm not buying another checker and couldn't find one with the correct ball sizes that I could get quickly. I seriously don't think the size of the ball on the end is going to affect anything, especially when I'm specifying total length. What we're talking about at that point is how much of the ball falls into the oiling hole. The difference would be something buried well below the other tolerances.

As you know, this cam is very mild.  I see no movement of either lifter at TDC firing, and for several degrees before and after. That tells me the lifter is indeed on the base, (or heel, as you call it).


So, my question stands. No matter how you measure it, is a span of 0.065" typical across 16 valves?

[blykins]

No it's not typical, but you also can't be accurate (especially to .001") with just counting turns instead of measuring with a set of calipers. 

The 3/8" ball will definitely give you different answers.  They make different tips for adjustable pushrods.  They are nice to have.  In your situation, throwing a bigger ball on the rocker arm end would end up giving you extra preload, which in most cases won't hurt anything.  However, if you're trying to measure to .001" accuracy with your length, I figured you'd want to carry that accuracy into the way the pushrod ball interfaces with the rocker arm.

In the same token of accuracy, the TDC method will work for very mild camshafts, but you really never know when the amount of overlap will introduce a discrepancy there.  The EVO method is considered the most accurate.

[jayb]

I think whether or not 0.065" variation is acceptable will depend on how much travel there is in the plunger of the hydraulic lifters.  I'd feel more comfortable with adjustable rockers, but if there is 0.150" or more of travel in that plunger, I think you could safely use the correct length pushrods and the non-adjustable rockers.  I'd probably go for a minimum plunger depression of 0.030" and let the rest of them fall up to 0.095".

Also, just an FYI that the variation in valve job from one valve to the next could easily account for the differences you are measuring.  Have you put a straightedge across the tops of the valves to see the differences in stem height?  I had a set of heads once where all the intake valves were about 0.085 higher than the exhaust valves.  Ran just fine, but I did have adjustable rockers...

[blykins]

Ok, I see what he's talking about now.   I was zoomed in on how he was taking his measurements, rather than looking at the big picture. 

I've never used a set of assembled Edelbrocks out of the box before, so I'm not sure how they do their valve jobs, although I would guess that they would try to get the tip heights the same???  On custom head stuff, the valve job will most certainly cause differences between the height on the  intake valve and the exhaust valve.  Hopefully Edelbrock spent some time on equalizing the valve spring pressures.  If it is in fact a .065" discrepancy, that could be a 20 lb swing in spring pressures. 

[scott foxwell]

There are several places that can cause this variation. First would be valve tip height. Lay a straight edge across the valve tips and see what you get. There can be a variation in the rocker stand pad height. There can be a variation in shaft stand height. There can even be a variation in the rockers themselves if they've been reconditioned...some may have just a little taken off the valve tip side, some may have been ground more. There will even be a variation in cup height in the lifters.
I would not be happy with .065 variation and I'd work pretty hard to find where it was, but that's just me. I had a lot of variation on my motor with stock heads, sharp rockers and I did a lot of "blueprinting" to the heads, decked my block myself, machined my rocker stands, etc. As "perfect" as I could get it, I think I still had .010-.015 variation from longest to shortest. I have adjustable rockers so I'm not too worried about but it still bothered me.

[CaptCobrajet]

The vast majority of differences with OE non-adjustable rockers is in the rockers themselves.  They are castings, machined in batches.  When they are reconditioned in a fixture, the differences in the original machining can be seen.  I hold valve tips to within .003.  Intakes all within .003, and exhausts all within .003.  Intake and exhaust are almost never the same.  When I started doing the hydraulic rollers with non-adjustable Ford rockers, I immediately and repeatedly saw wide variation, even when I knew the valve tips were spot-on.  I simply measure all sixteen individually, create a map, and make all pushrods within .005 of the exact length, plus desired preload.  Smith Brothers etches the length on each pushrod, and we install per the map.  I will usually have around half of the pushrods end up the same length, but it is not uncommon to have five or six different lengths in a set of sixteen.  Bolt them down and forget about it when the pushrods come.  You just have to either save the map, or take them out in order like flat lifters if it ever comes apart for some kind of service.  A little pain in measuring up front makes miles of trouble free service. 

I do think a person should make a checker with a big ball on the rocker end, just for consistency.  I turned the end off of a stock pushrod and pressed it into the end of a length checker.  Works like a charm.  If you make two of them, it makes the checking go much faster. 

[Pentroof]

I did notice the intake valves seemed taller. I went out and actually measured them and it's significant. Intakes are up to .022" higher, measured with a feeler. Remember, these are out-of-the -box Edelbrocks. (Well, almost...one of the two had no deburring/chamfering done in the chambers, as received).

I like the possibility of individual pushrods, Blair. I hadn't thought of that, thinking half sets would be the most "custom". I'll do a little more work with the spreadsheet and see how much overlap there is, using your suggested guidance above.

This is just a daily driver truck motor, so I'm not really hung up on nailing this to the last .001". However, that .065" kinda shocked me. This thing will never see life above 5000, especially with this cam.

I wonder if Smith Bros could also label them 1I, 1E, 2I, 2E, etc.? If not, I will.

[CaptCobrajet]

I think it could get confusing in the manufacture to further label them, but they will etch the length.  Two thoughts....... first, it doesn't matter what kind of rpm it will see.  You still need to preload the lifter accurately so it won't thrash or hold the valves open.  Second, invest in a cheap 12" dial caliper so you can measure with fair accuracy.  If you are within .005 either side of .055 preload, the regular Morel will be smooth and quiet.

[My427stang]

If you trust your measurements, I think first I would look close at cylinder 2, the short pair, and see if you have a stand that is a bit shorter.  It could be pulling down on the shaft skewing the responses and even pulling down the intake on #3  Might even be able to see it with a set of calipers loose, or try swapping stands and see if it follows.

If you pull the shorties out, the average exhaust becomes 8.724 and the loose one is at .020 delta

The average intake then becomes pretty tight at 8.714 with the worst delta at .010, likely within measuring error.

If I found something on that #2 stand, I think I would likely then measure every stand and make sure they are as close as they can be without getting crazy.

FYI, I am not countering anyone else's post, just looking at your table those 3 jumped out at me so I started playing with numbers.  Even with slight valve height differences, you may find a little filing or swapping of stands lets you get close and then you can either go with a single length or intake and exhaust.  FWIW if I was able to hit within a range of .040 to .060 preload cold on a hydraulic flat tappet, I wouldn't worry, but I don't have a lot of experience with hydraulic rollers in FEs, all that I have done were in SBCs and SBFs with adjustable rockers, so if Blair, Brent of Barry says .050-.060, I'd shoot for it

[Pentroof]

Ross, that's exactly where I started looking after thinking about the intake valves being taller and not translating entirely to the final numbers. The other tolerances are so bad (perhaps more in these rockers and stands than in the heads and lifters) that the valve tip height difference is muted.

Access to a 12" caliper isn't a problem, I just thought the checker tool would be accurate enough when we're talking about a .010" window with these juice lifters. I didn't think there would be this much variation across the valvetrain. In retrospect, I probably should have.


Off to check the stands... If I start to find things that really bother me, I'll either post a WTB for some adjustable roller rockers or refurbish a set of stock adjustables I have with bushings and modern adjusters.

[KMcCullah]

I've been in this pickle recently. And chose to make several compromises instead of fixing my valve job. Now l bend push tubes at 5800. Anyhow... If I had to do it again, I'd fix my valve job. Because the end result is a more balanced top end. All the springs are shimmed alike etc.

[Joe-JDC]

Intakes are fit taller because of the 30* seat on them vs the 45* seat on the exhaust valves.  The 30* seats don't cut down as far initially as a 45* seat does so makes the difference in new heads.  Some folks sink the exhaust seats on rework so that the stem heights are equal, but that is not necessary if you have an adjustable rocker arm set.  Joe-JDC

[Pentroof]

Well, it's not the stands. They all measure between 2.154" and 2.157. This is shorter than two other stock sets I have on hand, which makes sense for refurbs. Probably why I had to shim these up with valve spring shims to get a good sweep across the valves.