Rocker arm wear, oiling issue?

[Gregs672000]

So, come to find that the Isky cam had more interesting wear than we initially thought, and Delta wants to regrind it. Unfortunately they do not have the z-197 profile, so they will need to put it in the cam profiler and then set up to grind it, causing some delay. I did get the reground rockers back on Friday, and since I bit the bullet and had brand new ones sent from Dean, I decided I would try out my Racer Brown 341-R cam on the reground rockers and see how it runs. I cleaned out the cam with carb cleaner and compressed air just to be sure, installed the cam, did my best timing guess at it, spun the oil pump with a drill to confirm oil flow (no problems), checked for coil bind (not even close) and after playing with the carb jetting (she acted up, ran real rich at first but for some reason after swapping out some slow speed jets I went back to what I had and it was perfect again... go figure) I took her for a drive. I am still waiting for the specs on this cam, but it is my understanding that it has less lift and more duration than the Isky. I had never run this RB cam with the adjustable cam gear until now where it is (hopefully) properly timed and wanted to compare apples to apples. It is different from what I recall vs the Isky. It seems to have a bit less low speed response, as would be expected with more duration. I will get the specs from Delta later today. It comes on at about 3500 (vs 3200 Isky) and is very happy at 5000 rpms, pulling very hard and eager. I was trying to watch the road, my RPMs and my air/fuel meter at the same time and did not have a lot of time to really note things, but first impression is relatively good BUT I kinda feel like the Isky was better overall. I also had a single incident, scary moment at full throttle in 3rd gear as we hit 6000 rpms where it suddenly started popping and stumbling. I was watching my A/F meter and it was reading a safe 12.5 to 1, but I had noted some other readings of 12 to 1 when getting on it at times... a bit rich. It is possible that I was fouling out a plug, or that the Megajolt hiccuped, but I was concerned about detonation that I cannot hear (my hearing is just not what it used to be, too many years of drumming without hearing protection (stupid kid) has made my ears ring). I have never had any discernible knock or ping at high rpms, only at very low rpms and gears with a heavy foot, but I am only running premium 92 fuel (11.7 to 1 compression ratio). It has never done this before. It did not continue and the engine did not seem harmed, but I will want to check some things out. It almost acted like it had popped a rocker off the spring (that was my first impression) but it did not continue after I backed out of it and acted completely normal. I have no reason to think it could be valve float as they are lighter than stock and the springs are good. I did not do any more redline runs after that, but will of course.
So, any input on if the engine is likely to detonate at high rpm vs low given a 12.5 to 1 fuel ratio? I expect to get the Isky cam and new rockers back this week, and if time and weather permit this week will run the RB cam for a bit, make some notes and swap in the Isky to see how I like that. When I was looking at it, the Isky had the configuration I liked, with more lift but less duration, putting the power band a little lower but giving me a bit more performance. Still, we're talking a few thousands here so the difference may be subtle. A dyno run would be nice...

[JT68]

To tinker with the power band try varying the cam 1-2 degrees. On the back side of the sprocket, where the cam and sprocket meet on the cam flange, clean off the oil and take a fine point sharpie and make a line that shows the current position of the two. Try advancing the cam by one line width (about .020") relative to the sprocket. You can also make a tiny punch mark or pair of them, just something to mark the relative positions ant the cam flange. 2 cam degrees is 4 crank degrees, so certainly can move the powerband a few hundred rpms.

You may also need to tinker with your initial ignition timing and/or curve. Since the cam profiles are different, the sweet spot will also be different! Have fun, J

[Gregs672000]

Will do JT. I will spend some time with the engine in a more remote area where I don't have to worry as much about traffic, people or police and see how is runs as set now. There is no doubt that my crank timing marks are suspect, as even though I spent a lot of time determining TDC I did not have a degree wheel, and the mark is wide enough to be off a few degrees. Trial and error with as good as documentation as I can will help, but hours on the dyno would be the best to get objective data. Unfortunately I could not afford the hours! It will have to be seat of the pants dyno. Right now, I set the cam as close to the center of the locating hole and the end of the arrow on the cam cap as I could see, using a feeler gauge as a straight edge to try to be accurate. Guess the bottom line is, it could be anywhere (advanced, retarded or right on) and the only way to know if things improve or what happens is to do as you indicated until I get the best output I can, and adjust ignition timing and carb jetting as needed. This of course is a lot of effort, and would have to be repeated for each cam. I think I will get the various cam specs, document the RB cam a bit to really nail down where it makes power and when it drops off, see about changing its timing a bit to get the best out of it, then run the Isky and see how that is. I don't think I am near coil bind on either cam, do understand that the increased lift etc could increase wear. I do believe my rocker issue was more of an oiling issue (plugging), especially after running the oil pump with the drill... it took very little time to pump oil to the RB cam lobes. I will run new rockers on the Isky cam. Thanks as always for your input!
Any thoughts on possible detonation at high RPM?

[Gregs672000]

Did some more testing yesterday with the Racer Brown cam (still waiting on specs) and while I find it nice, I still feel the Isky was better. Granted, I have not done a lot of adjusting beyond my first effort to time the cam, and again this is rather suspect. However, it is pulling hard and running about how I would expect, suggesting that at least it is not terribly off. I'm still waiting on the Isky cam, but have been doing research on lift and duration and how it effects things. As is well known, increased duration tends to move the power band up higher in the RPM range. Higher lift can cause more wear on the valve train and one must watch for coil bind. The RB cam is no where near coil bind, I suspect the Isky will be fine too, but it has more lift and less duration. I thought the following was interesting info about the effects of lift as it relates to actually changing duration and how the engine idles etc. The graphs did not copy. This is from http://www.tildentechnologies.com/Cams/ ... mance.html

Cam Lift

Comparison of LiftThe intake and exhaust lift are the most important parameters after the four main timing events. For this discussion, we assume that the four timing parameters have been specified at 0.050 lobe lift, so the importance of lift is considered in this context.

There is no downside to lift. If there are no clearance issued involved, more lift is always better. It is easy to get more lift if you increase the duration, but here we assume that the duration has already been specified. Duration is more important than lift, so you never want to sacrifice duration for lift.

Consider the two lift curves at the right. Both have a duration of about 250 degrees at 0.050. In fact, the curves are identical below 0.050 lift. The difference in the maximum lift is only about 0.020, about 0.380 versus 0.360. If we assume these cams will be installed with a rocker ratio of 1.5, both will produce a valve lift in excess of 0.500. Some would argue that little additional flow occurs when you increase the valve opening from say 0.500 to 0.530, so why would you want a cam with this much lift? It is true that flow tends to level out at high lifts; however, the higher lift cam reaches intermediate lifts quicker, so the valve is open longer at these intermediate lifts. For the two cams shown, the duration at a lift of 0.250 differs by 11 crank degrees. Besides, once you've got the valve train moving, slowing it down abruptly to reduce the lift will trigger vibrations and require stiffer valve springs to counteract the deceleration. Constraining the lift makes sense only when there are clearance issues. In most cases the additional flow throughout the heart of the lift event is significant and it translates directly into improved performance.
Opening and Closing Rate

The ideal cam would be one that opens and closes the valve instantaneously at the optimum crank angles. This ideal cam would give a square lift curve. Instantaneous opening is not possible because it would require infinite acceleration of all the mass in the valve train and would lead to infinite forces on the valve train components. However, we should keep the ideal lift curve in mind and try to open the valve as quickly as possible. Harvey Crane's website has a page which discusses this issue. He uses the term intensity to measure the quickness of the cam opening and closing. Substituting the term "quicker opening" for "smaller intensity", Crane states, "In practical terms if two cams with similar lobe designs have the same duration at 0.050 lift, maximum torque and horsepower will be almost identical. However, the cam with the quicker opening will have a smoother idle, better off-idle response, superior low speed drivability and a broader power curve." Bakoni and Hollingsworth and Hodges also describe the advantages of quick opening cams.

Quick vs Slow Opening CamConsider the two lift curves in the graph at the right. The valve lash of 0.010 has been subtracted from these curves so that net cam lift is plotted. These curves are an exaggeration of the problem we frequently encounter with "performance" camshafts. Both cams have a duration of 250 at 0.050 (0.040 net) and a gross lift of 0.320. For this discussion, we want to concentrate on the difference between the curves for lifts below 0.040, i.e. the opening and closing. The differences may not look significant, but the seat-to-seat duration is 299 degrees for the quick opening cam (red curve) and 333 for the slow opening cam (blue curve). The slow opening cam has 34 degrees more overlap. For a 110 lobe separation, that translates into a whopping 113 degrees of overlap. The quick opening cam will have all the benefits cited by Crane. Actually, it's impossible to make the two lift curves the same above 0.040. The quick opening cam has 9 degrees more duration at 0.150. This increased breadth of the red curve above 0.040 will also contribute to better performance. The cam with the red lift curve will produce a broader power band by improving the low end performance of the engine, with a slight increase in the high end performance. As stated above, a high performance cam will invariably sacrifice low end power and torque for high RPM power. The sacrifice of low end performance is reduced using a quick opening cam.

Based on this, I am eager to try the Isky. However, I may go ahead and do a dyno run on the RB cam as she is now with the jetting and ignition timing map as it exists, then swap in the Isky and be careful of the timing and see what it does on a different day. While it may not be fully definitive about "which cam is better" for all engines, it may give some idea of what happens when swapping different cams for another (again, understanding that not all parameters are well controlled, i.e. this is not a scientific evaluation!).

[JT68]

Yeah, its really A LOT of work to properly, scientifically compare two cams with significant differences. Basically that is because the optimal setting for EvErY tuning parameter depends on the cam timing, ramp and overlap. Minor differences in ignition timing, mixture, valve closing points can easily make a 10hp difference and the difference between detonation or not. That is certainly enough to make the engine feel "really on" or "kinda sluggish". Bottom line is with these engines "optimizing" takes time and effort. Even with a huge $$$ dyno budget and an O2, it takes time, trial and error.

personally, I Find it a lot of fun! FWIW


One very misleading statement in the text " there is no downside to lift"....that has to be kept in context. The same article explains "over camming" your engine, and any cam manufacturer will tell you that the more you lift, the more you are stressing the metallurgy, wearing components, springs etc. No matter what the lift, everything has to be up to the job.

Also Greg if you don't end up needing the RB, I may have a use for it // j

[Gregs672000]

Appreciate that JT. I too enjoy messing around... to a point! Pretty soon I'm gonna want to drive it for fun, not for just for testing, and be settled that things are as I like them (Lord knows that doesn't always last that long though!). You're certainly right, there are so many adjustments one can make it gets a bit crazy, and after some time you get diminishing rewards. No need to chase a few extra ponies the car will never need on the street to be fun. 10 hp yes, 2 hp no... I want good driveability, dependability, confidence that it will not crap out on me when I'm making strong demands i.e "warp drive now, must pass idiot!" and be able to cruise relatively comfortably at speed with some efficiently given what it is (25mpg at 80 mph has been typical).
Always a work in progress, 30 years and counting! Getting closer every year

[Gregs672000]

Today my wife and I did a circumnavigation of Mt Rainier, starting on the northern side and coming back on the south. Truly a great drive, fantastic views, and some great roads.
Today was also a chance to see how the car is with the cam it has now. However, what was ubundantly clear was how true it is that everything is a system! What was perfect, dialed in carb jetting with the the Isky cam is overly rich in some places and lean in others with the Racer Brown. The power band and overall driving seems different, and I have to push the car harder to get the response I want, but then again the jetting is off for the cam, and who knows what it wants for a timing map, so who's to say what it would do with more adjustment to get everything working well together. And then I realized, all the jetting and the timing map was done with the Isky, so duh, there ya go...
It was nice to have the wide band because it provided clear evidence of what was going on for the carbs, otherwise one might just conclude the cam is not as "good" as the other. The reality is, one change made to one system effects all the others. Ya can't just drop in "the hot cam" and run it. And while i know that B and C cams were "made" for the U20, that is irrelevant; if you're gonna get the best result from your investment in cam and carbs (and in my case ignition timing as well), you're gonna have to mess with it some, and you're gonna need data. Once again, love the wide band, can't recommend them enough for those who like to tinker.
So, given that everything was set up for the Isky before, I plan to swap that one back in and see how it does when it's ready. I hope that things will go back to that dialed in condition as I have spent a lot of time working the other systems for them to all play well together!

[Gregs672000]

Ah, the continuing saga, and some lessons learned...
So, after much delay, I got the Isky back from Delta cam, and as we were planning a trip I wanted to install it, naturally last minute (lesson one: never procrastinate, should have addressed the cam issue over the winter). So, pulled the Racer Brown 341-R and installed the Isky. Checked for coil bind and we're close but I'm getting a 15thousands feeler gauge between 3 coils and that should be ok. Then after installing everything and timing the cam, I noted that the wipe pattern seemed close to the end of the pad on the adjuster side... way to close... almost off the end with the new rocker pads... doh! It was fine before, but the regrind reduced the base circle and that combined with the new rockers was enough for me to say that I can't run this! In desperation, I called around for last second lash pads, and ROSS from SPORTS IMPORTS came through BIG TIME, going WAY out of his way to get some overnight to me yesterday (not so easy considering the border issues). I was doing suspension work at the same time so I didn't get to the cam until 3pm or so... only to find that several years ago Steve and I must have decided to switch to L-series retainers, and the ones sent would not fit... Doh! Second lesson: Keep a journal of everything that has been done to the car! I probably could have found lash pads locally and saved time, effort and money. So, after a few choice words, some deep breathing, I accepted the situation and reinstalled the RB. The car runs fine, perhaps even a bit better than before as my cam timing may be happier... we're talking a few degrees difference, but that can be all it takes and unless you're setting it up with a degree wheel etc it's always best guess. I'm still eager to try the Isky though...

For those keeping track, the Isky has a lot more lift and nearly the same duration of the RB.
RB 341-R: Per Delta cam lift is 336 x 1.396 Roadster rocker ratio for a total of 469, duration 248 at 50 thousands.
Isky Z-197 measured 379 x 1.396 for a total of 529 lift, 246 duration at 50 thousands. As noted, we're closer to coil bind and this much lift will be more hard on the valve train, but with the modified head, bigger valves and higher compression, I should gain power everywhere and not lose torque or make it unfun to drive on the street.... it was great before! I made sure everything was cleaned out so it has plenty of oil flow, and I'm running new rocker pads so I hope it works long term. I will source some proper lash pads and run it before long. Good thing I like to tinker, but I also like to drive! Onward!

And again, a big shout out to Ross! He gave me the best chance of having this come together, and that was GREATLY appreciated.

[fj20spl311]

I still think "we" need to develop roller lifter patterned after the ford 2L-2.3L roller lifter.

[Gregs672000]

I still think "we" need to develop roller lifter patterned after the ford 2L-2.3L roller lifter.

You sound like Steve every time I go into the shop and talk cams! He's worked out a few solutions in his head, but doing it will take some development time and would not be cheap... how many would want this set up? What would someone be willing to pay? As a super busy guy, he has to make those considerations too, even though he's a great friend and likes helping me. It sure would open up a whole bunch of cam profiles that we think would really benefit the engine. Who knows, maybe this WINTER? Do I procrastinate? Yes. Have I learned anything... might depend on how long the rockers last with this grind!

[JT68]

I still think "we" need to develop roller lifter patterned after the ford 2L-2.3L roller lifter.

I've done a bit of work on it. It's about 3 X more than most owners would want to spend I'm quite sure. (Correct metallurgy, something that will last, high quality work). J

[fj20spl311]

I still think "we" need to develop roller lifter patterned after the ford 2L-2.3L roller lifter.

I've done a bit of work on it. It's about 3 X more than most owners would want to spend I'm quite sure. (Correct metallurgy, something that will last, high quality work). J

I agree, but as rocker get harder and harder to find?

It would mean new valves and retainers beside rockers and cam grind...maybe even a billet cam.

[JT68]

Roller rockers MUST be run with a cam designed for them (it would be a steel cam). The alloy requirements and actual cam profiles are very different from chill cast. It might become viable when the stock rockers and cam cores are gone,
but for now it would be $$$ compared to just $.

LMK if you seriously want a $2500 cam and rocker set - with 10 orders it could be done right now. (with some really fun profiles!)--Again this is really high quality work, not some trash from the orient that wouldn't make 10000 miles -- peace, j

[fj20spl311]

That's my understanding also.......Plus you might like longer valves and different retainer.
It sounds like a lot, but with $40-50 K cars it doesn't sound quite so much.

[JT68]

Agree. For a race engine project with deep pockets, it makes all kinds of sense (if allowed in the class).

But at least right now, I think most roadster owners would do a regrind or find a used cam for a couple hundred and run reground or new rockers as Greg has just done.