I took a few hours of my time today to do another "experiment"...

I'm open to suggestions on how to improve the procedure for the next time I do it.

Here goes:

After a leaky fuel pump, arcing coil, bad plug wires, 2 messed up distributors, a bad power valve, a bad starter solenoid etc, all on this test engine- I was able to find time to pull a valve cover to attempt to test whether or not "roller tip" rockers actually roll.

And the answer is.... sometimes.

The test mule:

1986 Silverado 305 bored .030, balanced.
NEW: rings, pistons, std main and rod bearings, cam bearings, factory spec Crane cam/lifters, pushrods, Summit roller tip rockers, valves, valve springs, re-sized original rods, polished original crank. Fresh 3 angle valve job, including bronze valve guides. Engine is on a Jegs "storage" engine stand.


The procedure:

After breaking in the cam, removed the drivers side valve cover and installed oil deflectors on the rockers. Oil still flies off the ends of the rockers at the valve end, but at least you don't get sprayed.
Cleaned the rollers & rockers so they could be marked with a permanent marking pen for reference.

One timing light strobe attempt-
Three 1:30 video attempts

Strobing a rocker with a timing light did not work for me because the pickup could not get a consistent trigger from the brand new 7mm plug wires I was using for testing (66 C2 327 design). I estimate the light fired 6-7 out of 10 times... enough to set timing, but not enough to follow the reference marks on the rockers.

So I switched to video... a Sony TRV260 8mm cam corder.

The first video attempt suffered from poor lighting and hand held jitters... and a nice coating of oil all over my camera & lense. Videotaped all 8 rockers.

The second video attempt suffered from improper angle and hand held jitters. Taped only cylinder #1.

The third attempt was done with a tripod and supplemental lighting, corrected camera angle. Again- Taped only cylinder #1.

It took me longer to remove the engine oil off the camera than it did to do the test. I wasn't a happy camper.

I imported the video to my video editor and ran it frame by frame.

At 600 rpm, as the rocker went full cycle, the reference marks on the roller did not move enough to say they "roll". There was gradual reference mark line mis-alignment as the engine ran, but according to the video, I could not see the lines rolling back & forth to indicate the roller was followimg the valve stem tip. Also- the reference marks did migrate on both engine startup & shutdown. Each time I shut the engine down & re-started it to re-do the video, I had to manually rotate the roller-tips to re-align the reference marks. They migrated in a direction which indicated they were followng the valve tip i.e.- what they were supposed to do when the engine was running.

Just for grins, I hand rotated the engine and observed the reference marks.... no movement.... no rolling.

Holes in the test:
1) The valve springs, although new, are relatively weak. (stock 305 truck)
Stiffer sping pressure will increase the loading between the roller and valve tip, which may/may not increase the amount of roll. Only another test with stiffer springs will answer that question. I can re-test when I build the next engine for my C2.

2) 600 rpm==> 10 rps==> 5 rocker events per second/valve
camera is (I believe) running at or near 30 fps.
But... I could still see occasional "holes" in the video stream when going frame by frame.

3) The computer video capture indicated no lost frames, but who knows.

4) Test was only done at idle because a) the oil was a big mess, b) anything above 600 rpm would quickly exceed the 30fps capture rate of the camera. I'll need to get a better camera to verify any movement at higher engine speeds (ain't gonna happen).

5) On the second & third videos, I only taped one rocker, since they all seemed to be acting identical.

6) The test was only done with one manufacturers design... others may vary.

So.... as far as I can see.. on a -mild- but new (un-broken-in) SBC, roller tips only rotate when they feel like it... inconsistently at engine startup & shut-down, but not at low speeds/idle. If they flat-spot (and I'll bet they eventually will because they aren't rotating), they won't move at all.

I don't feel like re-adjusting the rockers or going through the search & order process again, so I'll leave them in and drop the engine back in the truck. We'll see what "long-term" use does to them.

I'll report back in ten years.

 

Interesting. How about puttng some bright LED's under a vlave cover that has a cut out over the tip and some clear lexan or polycarbonate epoxied into it to keep the junk off your lense?

Inquiring minds want to know.

 

Thanks for taking the time to post the results Tom. I've always been curious about roller tips. It's always seemed to me they would eventually pick up a flat spot. Once they "seated" on that spot they would tend to slide rather than roll. Just thinking out loud.......

 

Nice research Tom. I enjoy your experiments and you document them well.

Thank for sharing.

 

You’re doing your fellow enthusiasts a great service.

 

Nice test, thanks for taking the time. I wonder what the rollers would be doing at 5000RPM ?

Also where roller rockers are usually mandatory are on higher lift dams with much higher spring pressures, I wonder if they would roll under higher spring pressures ?

And one thing that is good that if they are indeed not moving / rolling then that must mean that the friction between the roller and valve tip is less than it takes to move the roller on the bearing

 

Well i also wonder what they will do at higher rpm or different spring pressures.

Thx for sharing Tom as this is the kind of testing that the professional builders and mfrs do and are probaly trade secrets to them.

BTW i stumbled accross why the wear patterns rotate. From an old VW rebuild manual the solid lifter VW air-cooled engines where designed with a small amount of offset of the rocker tip over vlv tip center. Small enough to avoid side loading but enough to force the vlv to rotate and make the vlv clean its own seat (somewhat). This was really bugging my as i saw rotating wear patterns on my vlv tips from my roller tipped rockers with just a few hrs of operation.
So what i'm saying is that a rotating wear pattern is a good thing as long as it's not too close the the edge of vlv tip - caused by a less than perfect roll over center of vlv tip.

cardo0

 

Visually, these are all dead center... the rollers are centered on the valve tips. Of course, if they could be measured to .001 or .0001 there's probably some variance. As far as I can tell, the reference marks only changed when starting the engine, and when shutting it down... not while running. If it keeps doing that, and the rollers wear evenly, then there is no big deal. If they wear to a flat-spot... that will throw the rocker adjustment off due to the increased clearance. The rollers are already showing signs of wear patterns after about an hour of total run time.

I don't think they are worth the investment at this point. All I was looking for was reduced side loading on the valves & guides.... not performance. In other words, I'm not impressed with the technology. That may change when I re-test with stiffer springs on my next C2 engine. I actually have a new 327/350 cam, lifters, vales & springs in a box ready to go, but can't decide to keep the 327 or go BB. Curiosity has gotten the best of me... now I have a "need" to know.

 

I think i've read the thumb rule is 1/2" lift for rollers/roller tips. As the vlv lift increases the wipe patch area increases closer to the edge causing side loading.

But i do reget spending for CC Mag roller tips when my vlv lift is only .440" as i did have problems with the CC locking nuts. And could have bought the generic non-roller tips for have the price and have really the same results. BTW i still have a brand new in the box set of Crane 1.5 stamped rockers (non-roller tip) and Kool Nuts as i don't trust the CC vlv train yet.
Actually a non-roller tip is just 1 or 2 less parts to break and fail.
Well hindsight is allways greener and i could have save several hundreds $$$$ and made more pwr using what i have learned through the upgrading process. And i try to help others here too but ya know human nature is such that most have to learn for themselves.

Good luck and thx for sharing. cardo0

 

love to see

 

From my point of wiew if roller rocker tips roll on the valve then ok but no big deal. The big advantage is that the pin or bearings holding the roller tip roll in the rocker, less drag.

 

I had the CC 1.6 ratio roller tips on my previous 350 engine. After 9000 miles I could not say that there were any flat spots worn on the rollers. One did have a slight groove in it, much like what a carbide scriber might do.

 

The Summit roller tip rockers have stationary pins that hold the roller... the pins do not rotate... so if the roller is not rolling, then nothing is.

 

What? The video?

I have 3 AVI files.

 

Since I machined the heads myself, I was able to take a real close look at the wear conditions in the original valve guides. They were "side loaded"... wear pattern was very clear on the guides & on the valve stems. The "wobble" was much more severe side-to-side then front-to-back. My measurement equipment verified the "egg". These are original, factory heads & valve train on a 1986 Silverado 305... very low performance & lift. The valves were not rotating... they were worn in a pattern following the side loading. This is why I bought new valves & installed bronze valve guides, and is what prompted me to try the roller tips. Otherwise, I would have just refaced the valves & bought stamped rockers. Everything was toast from the side loading. Since I have been doing valve jobs for 30 years, I'm, used to seeing the results of side loading.

I can see it being a bigger problem on high lift cams/rockers... makes sense to me.

I guess there will have to be a sequel. LOL

 

Tom, I think I have to agree that for most the roller tip rockers are not worth the value and are more like fishing lures for fisherman. However I looked over the Magnums I've been running for the last year and see a definate continuious wear pattern.

With this information and the roller cam I went for the Pro Magnum 1.5's.. We'll see what I get but with the lift I have and duration I thought it was money well spent also with the increase spring pressures I think the fulcrum rockers will reduce any problems I might have..... Maybe I just have to much expendable income... Dave..

 

Yup... the rollers on my test rockers also have a continuous wear pattern developing on the entire circumference of the rollers... I looked at them with magnifying glasses. They are wearing all the way around... but this must be simply the result of the slow rotation while running & startup/shutdown. They definitely are not rolling as hoped with every wipe of the valve tip. I'll email you the video or you can come over & see for yourself. Again, my disclaimer says that this test was done with only one design/brand of roller tip rockers.... we have to beware of apples/oranges comparisons.

 

Tom - I think that when you start exceeding .600 lift your tip is covering more of the valve stem end.

I felt much better with how bullet proof the CC roller tips were over stamped rockers.

 

I won't be building any .6 lift engines in the near future... so that test will have to be up to someone else.

I will be building two .5 lift +/- engines though.... so I'll be able to retest with one of those.

Stamped steel non-roller rockers are pretty bullet proof also... I've never seen the end break off a stamped steel rocker, but I have seen roller rockers that have self destructed.

My test was for a specific item.... specific valve spring pressure, specific lift.

No data for anything else.

Bottom line is, they did not rotate to follow the valve stem tip under those conditions. Re-stated- on a .34375 diameter valve tip (less the chamfer) the roller did not roll .34375 on the circumference.

Now, let me throw something else out there ..

I looked at 8 rockers. One of them did not move no matter what. Maybe it will feel left out after a while and start moving with the rest of them.

The reference marks on the other 7 did gradually rotate in the desired direction, showing at least some movement.

My guess is that the roller moved at the peak of the valve lift & pressure (fully open), and, it didn't completely roll back on the close stroke. This would account for the slow/minute reference mark movement while running.

I would say this is a good thing... at least the roller shouldn't flat-spot, and maybe it rotates at the point of maximum side-loadiing... which is -sort-of- what I was looking for.

The most movement I saw was at start-up & shutdown.
But the fact that the lines did migrate a smidgen means that the rollers are rolling... just not the way I expected them to.

The question is when & how much. Definitely not a full wipe while running... at least not with these particular rockers & springs.

Probably a misconception on my part... maybe this is exactly how they are supposed to function. ... no movement under light load, as the load increases, more movement (proportional to spring pressure), and less/unequal movement on the close stroke to allow even roller wear.

???

 

ya' is there a link ?