[Grant4060]

Originally Posted by millerrockers

The illustration from Comp Cams is not only the WRONG thing you want, it is the worst thing you want. It is the anti-mid-lift scenario. The correct "symptom" that would be illustrated in the valve motion atop the valve tip would be A to B then back to A, there is no C. The roller sweeps out to its farthest point at precise "net" valve MID-LIFT, then rolls BACK to the inside of the valve as it reaches maximum net Valve Lift.

Secondly, any reference to the "middle of the valve" for setting, seeking, or designing is NOT correct, and it is not why MID-LIFT sets up the way it does. I have said it a million times, "where the roller sits atop the valve means nothing, providing it stays atop the valve." Because of the myriad of dimension variables involved, setting mid-lift geometry correctly, AND trying to get the roller in the middle of the valve is nearly impossible. It doesn't matter anyway, PROVIDING you have the rocker set at precise mid-lift.

The whole purpose of MID-LIFT is for CAM timing, NOT reduced wear on the guides, or valves, or minimum sweep atop the valve, or reduced drag coefficients in the rotating valve train. But these are all the "symptoms" that are beneficial, because you get ALL these when you set for mid-lift geometry. The main purpose, is to convert as much of the CAM'S information accurately, through the radial arc process with the least amount of radial converion loss. IT "standardizes" all cam testing data. Without setting the rocker geometry accurately, to mid-lift, you are wasting SEVERAL degress of cam information in the excessive motion of an overarcing pushrod and roller tip

Please NOTE that I said "pushrod" AND "roller tip." All your theories for setting rocker geometry on the valve tip, by measuring the sweep, getting it as least as possible, and making a variety of different little tools to measure this, do NOT have anything to do with what is happening on the other side of the rocker, and the MOST IMPORTANT side: the pushrod cup. This is where all the trigonometry is taking place. THIS is where ALL THREE of the cam's dynamics are either being fully "captured" for translation through the radial process, or LOST -- and the element that determines this is a 90 degree tangent point in the pushrod ball AXIS at precisely "MID-CAM-LIFT".

So when you are setting the valve side with a Comp Cam rocker, or a Jesel, or a (gag) Scorpion rocker, you're NOT setting the pushrod side TOO. You're only setting the valve, and the more important side is still over-arcing, because the position of all the other rockers, compared to the Patented mid-lift design, are TOO high in the body, so the pushrod has already passed through its mid-lift, and it is overarcing trememdously, and the pushrod is moving in out about .050" or .100" -- when it should be only moving about .013" in and out, so its harmonics are like a BASS guitar's E-string, and you've just lost about 6, 8, 10, 12 or more degrees of your camshaft THROUGHOUT the entire valve lift cycle. So that 265 degree cam (@ .050) is now only 255 degrees.

The difference can be felt and seen with an old fashioned needle torque wrench. An engine of bad rocker geometry will typically take 15 to 40 lbs more torque to turn over (without spark plugs of course), than a MID-LIFT system, properly installed. I want to emphasize this last point "properly installed." If you are off by as much as .020" of an inch (1/2 of 1 turn on an adjusting screw) you will lose 2 or 3 degrees of your camshaft. God only knows how many engines are running around, blindly happy because they don't throw their parts out the headers (yet), with .050", or .100" or .150" too long a pushrod (or worse), and stand heights all over the place.

Cam information! Getting it all through the system to the valve, with the least amount of wasted motion, so that a "standard" was set that would measure EACH cam tested without having its differences be diluted by a rocker arm stealing the information.

THAT is why I designed mid-lift. Hope this clears up some of the rhetoric. Good luck! --JM

Jim, much appreciate this information! However, I'm working with an NHRA stock eliminator engine with the 502 BB stamped steel rocker arms and a Comp Cam custom ground with likely a non stock base circle diameter. The valves also may not be exactly at stock stem length. I'd like to optimize the valve train geometry, but unlike your explanations have no axle shaft centers to measure. Could you explain how I could proceed with readily available tools such as dial indicator, checking pushrod, etc to check and correct my geometry? Can I use the rocker arm stud as a reference point and a protractor to either the pushrod tip and/or the valve tip? Perhaps at the mid-lift point? I have already tested two pushrods .100 different in length and noticed the longer one produced more lift at the valve but also a wider swipe pattern that moved inboard a bit compared to the shorter pushrod. The reason I initially tried the longer pushrod was to get closer to my allowed lift of .398". With a .240" lobe lift and theoretically 1.7 rocker arm ratio the calculated lift would be .408", but using race springs at 210/400 lbs pressure I was only achieving .382" valve lift after deflection losses. After reading these posts, I'm thinking that I might be better off sacrificing maximum lift and trying to get the narrowest swipe pattern on the valve stem tip by testing different lengths using the adjustable pushrod? You've mentioned that could get it close, but how do I get it optimum? What do I need to do to get the best power and performance, given that I can likely only change the pushrod length, or after establishing that length possibly having another cam custom ground with more lobe lift to reach the spec. maximum. Would very much appreciate your advice, thanks!
grant4060

[cobalt327]

Originally Posted by Grant4060

Jim, much appreciate this information! However, I'm working with an NHRA stock eliminator engine with the 502 BB stamped steel rocker arms and a Comp Cam custom ground with likely a non stock base circle diameter. The valves also may not be exactly at stock stem length. I'd like to optimize the valve train geometry, but unlike your explanations have no axle shaft centers to measure. Could you explain how I could proceed with readily available tools such as dial indicator, checking pushrod, etc to check and correct my geometry? Can I use the rocker arm stud as a reference point and a protractor to either the pushrod tip and/or the valve tip? Perhaps at the mid-lift point? I have already tested two pushrods .100 different in length and noticed the longer one produced more lift at the valve but also a wider swipe pattern that moved inboard a bit compared to the shorter pushrod. The reason I initially tried the longer pushrod was to get closer to my allowed lift of .398". With a .240" lobe lift and theoretically 1.7 rocker arm ratio the calculated lift would be .408", but using race springs at 210/400 lbs pressure I was only achieving .382" valve lift after deflection losses. After reading these posts, I'm thinking that I might be better off sacrificing maximum lift and trying to get the narrowest swipe pattern on the valve stem tip by testing different lengths using the adjustable pushrod? You've mentioned that could get it close, but how do I get it optimum? What do I need to do to get the best power and performance, given that I can likely only change the pushrod length, or after establishing that length possibly having another cam custom ground with more lobe lift to reach the spec. maximum. Would very much appreciate your advice, thanks!
grant4060

Until he gets back, a couple things. I doubt the base circle will be any smaller than stock for such a low lift cam, and if it IS, I'd suggest you get a larger base circle cam to replace it. Small BC cams don't have the dynamic stability of a larger BC cam, IMO.

I'm going to guess your spinning this mill up pretty good. If so, and w/the deflection you're seeing, I'd have to say that a thicker wall pushrod would help w/the deflection issues- I cannot see there being a need for there to be 0.026" deflection, even w/some losses associated w/the geometry.

[Grant4060]

Cobalt 327,
Thanks for the help! Actually I'm wondering if the base circle is larger than stock, because the lift is so low maybe they used the available room to create a more stable profile on a bit bigger overall lobe. This cam is extremely radical, the lobe is at full lift for a long time with very steep ramps, looks like a roller cam. We are allowed any duration but only stock lift, so the valves open very quickly and need tons of spring pressure to control the valve train and get any rpm. I'm trying to get 7000 out of it for rpm. The pushrods are Manton .120" wall, and the rockers are modified 502 Marine with a welded re-inforcement above the pushrod cup done by Clark Holroyd. The rocker studs are even oversize tool steel units with special polylocks with a wide base to fully support the rocker ball. I'm amazed at the deflection too, I first tried total lift with a light checking spring and came up with .420"! Something is definitely in need of correction, I'm thinking. On Saturday I'm going to try measuring the amount that the pushrod moves toward and away from the valve, that may be another way to see how far out the geometry is, and also get some patterns on the valve tip using an adjustable pushrod going shorter than the pushrods I've tried previously.

[cobalt327]

I imagine the way that you describe the lobes on your cam, that it's as hard to stabilize as many radical cams- just yours doesn't have the big peak lift numbers. But the starting and stopping is what's hard on things. Good to see you're on top of the deal, those p-rods sound plenty healthy, and the rest of the valve train specs seem to be well thought out. Hopefully you will get something to try regarding different p-rod length/geometry 'correction'.

[lash540]

I know this topic has been talked to death already but I just wanted to put my 2 cents in. I looked into this stuff about 5 years ago and stopped looking at it as fast as I started. It looked like somebody trying to re-invent the wheel. I have been building engines from stock smallblocks to race ready big blocks for the last 10 -15 years. I consider myself fairly knowledgeable but not a genius by any means. A friend of mine recently asked me what I think about patterns on the valve stem and pushrod lengths and I kind of just brushed it off. Soon after, I was doing some work on my own race engine and decided to look into Miller's website, his parts and tech again. Now I understand what the whole principle is here and I am not disagreeing with how it works but I don't get what all the fuss is about. 99% of the stud mounted roller rockers out there are not Miller rockers so the majority of people are not going to be able to duplicate his results 100%. Now I know for all you high tech guys and perfectionists out there that think Miller is a god and can do know wrong, there is no other way to think about this topic. But there is another way. I know for a fact there is more people in the real world finding pushrod lengths with a " toy closed valve pushrod checker" than not with great success and nowhere near spitting parts out there exhaust. From my experience I have never seen engines eating themselfs apart because of using the regular checking method. Now my opinion is if you have valve lift .500 or smaller checking this to death is going to give you minimal to no gains in horsepower and is not going to kill your guides. If you have .700 or more you should be looking at a high quality shaft rockers that give better results anyway. What I don't like is someone like Miller talking like cam companys are bad and everyone that doesn't follow his methods and buy his products are wrong. Everybody should realize that Miller products is a business just like any other company and he wants your money too. His method is just another method, not right or wrong, it may work better but how much better? I don't really here anybody talking horsepower gains/loss or how much wear you have accumulated using the other method, all I keep reading is theory. So it sounds like a matter of opinion wether it's worth it on a low powered stud mounted motor. I guess what I'm trying to say in my rambling is if you don"t follow his teachings it doesn't make you wrong or an idiot. As he says, " I'm not trying to slam anyone here" but the logical thing for most people to do is buy a good quality rocker and do the best you can with it. That extra .050 thou + or - on your pushrod is NOT going to give you that extra ten horsepower or stop your motor from self distructing.

[ap72]

Originally Posted by lash540

I know this topic has been talked to death already but I just wanted to put my 2 cents in. I looked into this stuff about 5 years ago and stopped looking at it as fast as I started. It looked like somebody trying to re-invent the wheel. I have been building engines from stock smallblocks to race ready big blocks for the last 10 -15 years. I consider myself fairly knowledgeable but not a genius by any means. A friend of mine recently asked me what I think about patterns on the valve stem and pushrod lengths and I kind of just brushed it off. Soon after, I was doing some work on my own race engine and decided to look into Miller's website, his parts and tech again. Now I understand what the whole principle is here and I am not disagreeing with how it works but I don't get what all the fuss is about. 99% of the stud mounted roller rockers out there are not Miller rockers so the majority of people are not going to be able to duplicate his results 100%. Now I know for all you high tech guys and perfectionists out there that think Miller is a god and can do know wrong, there is no other way to think about this topic. But there is another way. I know for a fact there is more people in the real world finding pushrod lengths with a " toy closed valve pushrod checker" than not with great success and nowhere near spitting parts out there exhaust. From my experience I have never seen engines eating themselfs apart because of using the regular checking method. Now my opinion is if you have valve lift .500 or smaller checking this to death is going to give you minimal to no gains in horsepower and is not going to kill your guides. If you have .700 or more you should be looking at a high quality shaft rockers that give better results anyway. What I don't like is someone like Miller talking like cam companys are bad and everyone that doesn't follow his methods and buy his products are wrong. Everybody should realize that Miller products is a business just like any other company and he wants your money too. His method is just another method, not right or wrong, it may work better but how much better? I don't really here anybody talking horsepower gains/loss or how much wear you have accumulated using the other method, all I keep reading is theory. So it sounds like a matter of opinion wether it's worth it on a low powered stud mounted motor. I guess what I'm trying to say in my rambling is if you don"t follow his teachings it doesn't make you wrong or an idiot. As he says, " I'm not trying to slam anyone here" but the logical thing for most people to do is buy a good quality rocker and do the best you can with it. That extra .050 thou + or - on your pushrod is NOT going to give you that extra ten horsepower or stop your motor from self distructing.

It doesn't make you an idiot, but it is wrong. Its not a disasterous error and a lot of people make it but wrong is wrong. BTW you don't need millers rockers to set them up like this it is the way all stud mounted rockers should be set up, even if you're using stock stamped rockers. The added lift is only slight and the decreased wear can vary but the bennefits are still there and the total extra cost is $0.00 if your buying pushrods anyway- which most of us do.

[lash540]

I agree it's not a disasterous mistake and I know that you don't need his rockers to set it up that way but you won't get the full affect without them. Don't get me wrong, I am not saying to ignore what he is saying, that would be ignorant. Like I said, I think you should set whatever rocker you have up the best you can. But his attitude is that if you don't set it up to the thousandths your going to lose a whole bunch of lift/duration and down the road your engines going to self destruct. I guess what rubs me wrong is Millers attitude about the big cam and rocker companys not allowing themselves to be drawn into this silly argument and that he is out to save the grass roots guys. It would not be benificial for Comp but it would for him. Even if he's giving out free information, he's doing it to sell products. I have no problem with people going the extra mile to get every last bit out of there engines but the majority of people buying rocker arms are not stock and superstock racers and are never going to see the difference. A lot of people just want to get a pushrod that fits in their engine and doesn't bind up their rocker arms and thats okay too. You can call it right or wrong but you can't change it. Anyways sorry to ruffle any feathers but I had to get it off my chest.

[Grant4060]

I've now tried the Miller approach on my engine, and was lucky enough to obtain a set of his rockers from a guy who'd bought them years ago but never used them. First, I tried setting up a new set of the newest light Comp steel roller rockers using the Mid Lift method. If I got a nice narrow pattern on the valve stem tip, using an adjustable pushrod, at the other end the pushrod was moving in and out about .035". If I shortened the pushrod to the point where the pushrod only moved about .010", I had a much wider swipe at the valve stem. My conclusion was that I could not achieve good geometry at both ends with these rockers. I found that after lengthening the pushrods to get Mid Lift geometry with the Miller rockers, I had a narrow line contact pattern at the Valve tip AND a movement at the pushrod of less than .010" plus the movement was out then in as the pushrod reached mid lift then passed it! In my mind, this proves the benefit as the pushrod is reaching the exact furthest point away from the stud then passing it so arcing the least possible amount. On the dyno, my engine made 518hp which is pretty good with a factory cast iron intake, Q jet and .398" lift flat tappet cam. To me, it is a new area that I learned about initially by reading this forum and the posting by Jim Miller! I'd also like to thank Jim Miller for being generous enough to reply directly to my email and answer my questions, even though he is not currently selling his patented design regular rockers except in limited production of his top of the line Pro Stud rockers. Guys, if you sit down and draw it out, each end of the rocker arm moves in a circle but they are different circles. To me, being at 90 degrees to both the pushrod and the valve stem at half lift is getting the most efficiency from the valve train geometry. Miller has figured out the exact angle between the two ends of the rocker that will accomplish that goal, it would be interesting to see which, if any, of the other rocker arms on the market are manufactured with the optimum angle. I'd suggest we all encourage Miller to start production again, clearly it does work as he describes with the correct length pushrods. Note that I have a 396 Chev 325hp engine, the lengths are different between intake and exhaust as well as different amounts longer than stock. Each engine must be measured and checked with the actual cam you will be running. If you change lift it will likely change the pushrod length required, as will milling the block, heads, longer valves etc. The pushrods need to be determined last, to ensure getting the best geometry. Just my 2 cents worth on an excellent subject.....

[lash540]

I will tell you a situation we had just a little while ago, we kept lengthening a pushrod on a big block chev until we got maximum lift, about .013 thou over the pushrod with the "right" geometry. I had been reading a lot of talk on this forum and we were going on the dyno with it so I decided to take a set of long pushrods in with us. They were pretty long but nothing was binding up. To make a long story short the longer pushrods made a few more horsepower, not a lot but it was there. We then put 1.8 rockers on the exhaust with the same pushrods and gained 10 horsepower. If it matters the engine was a 760 horse 454. Now do I tell the customer we have to put the shorter pushrods in and make less power to make the geometry "right". I know this engine won't have problems because I have seen it done for many years. All theories need to be tested ,not just drawn on paper or swipe patterns but on the dyno or race track and they need to be tested back to back. All Jim Millers website has is theories, sarcasm and negativity to other companies. This gets too complex for the majority of people whether you like it or not, and these are a big portion of the customer base. I have viewed both sides of the story and believe this whole thing has been blown out of proportion for a stud mounted rocker and that's probably why it hasn't really caught on and why he doesn't make them anymore. Grant 4060, did you test his rockers against the comp rockers on the dyno? and if not how can you know for sure that they worked for you? All I am saying is too much classroom and not enough real testing.

[oldbogie]

Originally Posted by lash540

I will tell you a situation we had just a little while ago, we kept lengthening a pushrod on a big block chev until we got maximum lift, about .013 thou over the pushrod with the "right" geometry. I had been reading a lot of talk on this forum and we were going on the dyno with it so I decided to take a set of long pushrods in with us. They were pretty long but nothing was binding up. To make a long story short the longer pushrods made a few more horsepower, not a lot but it was there. We then put 1.8 rockers on the exhaust with the same pushrods and gained 10 horsepower. If it matters the engine was a 760 horse 454. Now do I tell the customer we have to put the shorter pushrods in and make less power to make the geometry "right". I know this engine won't have problems because I have seen it done for many years. All theories need to be tested ,not just drawn on paper or swipe patterns but on the dyno or race track and they need to be tested back to back. All Jim Millers website has is theories, sarcasm and negativity to other companies. This gets too complex for the majority of people whether you like it or not, and these are a big portion of the customer base. I have viewed both sides of the story and believe this whole thing has been blown out of proportion for a stud mounted rocker and that's probably why it hasn't really caught on and why he doesn't make them anymore. Grant 4060, did you test his rockers against the comp rockers on the dyno? and if not how can you know for sure that they worked for you? All I am saying is too much classroom and not enough real testing.

Think Jim's concept works better on engines with very long rockers like those of the Ford Shotgun Hemi 429 where the angles, dimensional relations and lengths warrant close attention to the distortions of circular movements.

I do run a set of his rockers on my Franken-mouse 350, but while a pretty stout engine, it is a daily driver not a race engine. They've been there for nearly 200,000 miles without issue.

Bogie

[Grant4060]

Originally Posted by lash540

I will tell you a situation we had just a little while ago, we kept lengthening a pushrod on a big block chev until we got maximum lift, about .013 thou over the pushrod with the "right" geometry. I had been reading a lot of talk on this forum and we were going on the dyno with it so I decided to take a set of long pushrods in with us. They were pretty long but nothing was binding up. To make a long story short the longer pushrods made a few more horsepower, not a lot but it was there. We then put 1.8 rockers on the exhaust with the same pushrods and gained 10 horsepower. If it matters the engine was a 760 horse 454. Now do I tell the customer we have to put the shorter pushrods in and make less power to make the geometry "right". I know this engine won't have problems because I have seen it done for many years. All theories need to be tested ,not just drawn on paper or swipe patterns but on the dyno or race track and they need to be tested back to back. All Jim Millers website has is theories, sarcasm and negativity to other companies. This gets too complex for the majority of people whether you like it or not, and these are a big portion of the customer base. I have viewed both sides of the story and believe this whole thing has been blown out of proportion for a stud mounted rocker and that's probably why it hasn't really caught on and why he doesn't make them anymore. Grant 4060, did you test his rockers against the comp rockers on the dyno? and if not how can you know for sure that they worked for you? All I am saying is too much classroom and not enough real testing.

Lash540- I did not dyno the Comp rockers, or dyno test different length pushrods. We wanted to achieve the least lost motion then compare with our previous engine testing from a few years ago. We set the National Record with the old engine, and knew we had 500 hp at that time. We have done several things to try and improve the engine, a different valve job, lightweight valves and the Miller rockers, and 7/16" .120" wall pushrods to gain the 18hp. But, we've also lowered the cam lift from .460"/.480" to .398" lift for the lower horsepower rated engine so we are very happy with the results! Our car can now be 160 lbs lighter and is making 18 hp more, running in the same class.
Yes, it is more trouble than most would bother to do, lots of measuring, checking, adjusting and then ordering the custom length pushrods for $13. each, but these areas are where you need to look for incremental gains on a rules limited class racing engine. Our engine is more efficient now, as indicated by the Brake Specific Fuel Curve compared to the previous tests, so should accelerate quicker. As someone posted earlier, there is no extra cost if you are building your own engine, you'll be buying pushrods anyway.
It is an interesting experiment, you can see the pushrod deflection change with a dial indicator as you change the pushrod length, and also observe the swipe pattern on the valve tip with gear marking compound or bluing.
Obviously, you took offense with Miller's remarks regarding the manufacturers, however he has a point. At our machine shop we've had many, many parts from "name" major manufacturers that were incorrect, mis-designed and did not fit or function out of the box as they were intended. Even after the problems were reported, no changes were made in newer orders of the product!! I'm still hoping someone will post here that has tested various brands of roller rockers to let us all know if there are any that check out well using the Miller Mid Lift approach...

[lash540]

Interesting points. Good luck with your car.

[cobalt327]

Grant4060, what class are you running in? Are there restrictions on the valve and seat angles? I ask because at those low lifts I'd be curious to know what an angle less than 45 degrees would do for the low lift flow.

[Grant4060]

Originally Posted by cobalt327

Grant4060, what class are you running in? Are there restrictions on the valve and seat angles? I ask because at those low lifts I'd be curious to know what an angle less than 45 degrees would do for the low lift flow.

We run NHRA stock eliminator with any valve job allowed. I'd encourage you to do some flow tests and see what your particular head likes at low lifts. Pay attention to the .200" and .300" lift numbers. Some Ford and GM engines use a 30 degree seat from the factory on low lift street engines. Seem like high lift engines use 50 or 55 degree seat angles on high flow heads. Just like the pushrods, it's a lot of work. It will likely be a combination of angles- the top cut, the seat itself and then the throat where you might consider more than one angle or on the exhaust a radius might be beneficial. The valve itself may want a backcut, or not. Then what angle backcut? We tested with 32, 30, 28, and 24 degree backcuts as well as none on each set of seat angles we tried. Some like a tiny chamfer on the outer edge of the valve. I'd use a spare casting, we probably have 50 pages of flow tests because there are so many possible combinations to try. No one will tell you exactly what works best, even if they know on your particular combination because it takes so much time and effort to figure it out. You always wonder too, if you could have gotten it even better with more tests, more different widths of cuts or angles. If you can find a real expert, it might save a lot of effort to pay to have a guru do your good castings. Just my 2 cents, good luck!

[millerrockers]

[QUOTE=lash540]I know this topic has been talked to death already but I just wanted to put my 2 cents in. I looked into this stuff about 5 years ago and stopped looking at it as fast as I started. It looked like somebody trying to re-invent the wheel. I have been building engines from stock smallblocks to race ready big blocks for the last 10 -15 years. I consider myself fairly knowledgeable but not a genius by any means. A friend of mine recently asked me what I think about patterns on the valve stem and pushrod lengths and I kind of just brushed it off. Soon after, I was doing some work on my own race engine and decided to look into Miller's website, his parts and tech again. Now I understand what the whole principle is here and I am not disagreeing with how it works but I don't get what all the fuss is about. 99% of the stud mounted roller rockers out there are not Miller rockers so the majority of people are not going to be able to duplicate his results 100%. Now I know for all you high tech guys and perfectionists out there that think Miller is a god and can do know wrong, there is no other way to think about this topic. But there is another way. I know for a fact there is more people in the real world finding pushrod lengths with a " toy closed valve pushrod checker" than not with great success and nowhere near spitting parts out there exhaust. From my experience I have never seen engines eating themselfs apart because of using the regular checking method. Now my opinion is if you have valve lift .500 or smaller checking this to death is going to give you minimal to no gains in horsepower and is not going to kill your guides. If you have .700 or more you should be looking at a high quality shaft rockers that give better results anyway. What I don't like is someone like Miller talking like cam companys are bad and everyone that doesn't follow his methods and buy his products are wrong. Everybody should realize that Miller products is a business just like any other company and he wants your money too. His method is just another method, not right or wrong, it may work better but how much better? I don't really here anybody talking horsepower gains/loss or how much wear you have accumulated using the other method, all I keep reading is theory. So it sounds like a matter of opinion wether it's worth it on a low powered stud mounted motor. I guess what I'm trying to say in my rambling is if you don"t follow his teachings it doesn't make you wrong or an idiot. As he says, " I'm not trying to slam anyone here" but the logical thing for most people to do is buy a good quality rocker and do the best you can with it. That extra .050 thou + or - on your pushrod is NOT going to give you that extra ten horsepower or stop your motor from self distructing.[/QUOTE]

Gee, I never thought of myself as professing any "teachings." But rather than try to dismantle the logic professed in these comments, here's the bottom line, and you can call it "theories" or "teachings" or whatever you like.

If you buy a cam that is supposed to be 265 degrees at .050" tappet lift, and after you've decided to just follow any old quickie fixed so called "pushrod checker" method, you find you only have 255 degrees of VALVE reaction, because you just let 10 degrees go SOUTH with the .165" in-and-out Push-rod motion, instead of the .017" that it should be... would that be a theory that you probably didn't do something right? Is that even a decision of "right or wrong?" (It's a rhetorical question.)

You're entitled to your opinion, but I never said any cam companies were bad. I just said they either don't know what "better" is (read: EFFICIENT), or they just don't care, because they hung their hat on rhetoric and advertising about rocker arms long before I published what "correct" rocker geometry is.

CORRECT rocker geometry, like anything in engineering, is "efficiency." It makes little sense to have something moving more than it needs to transmit information from the cam to the valve, ending up with excessive motion, excessive drag coefficients; excessive heat (friction); excessive HARMONICS (the worst bi-product), and excessive WEAR on parts. Now, if you're definition of efficiency is something different, then you're entitled to your opinion.

You don't need to spend ten cents with me on MID-LIFT parts to confirm or deny what the consequences are. You can make the geometry changes with any rocker system made, IF you spend the time doing it.

One last point, CHRYSLER and CHEVROLET didn't adapt MID-LIFT for their race teams because it was a "theory." When cam companies like Comp Cams, who KNOW BETTER, continue to misinform engine builders with their totally opposite efficiency illustrations as they have, I don't really know what to call them, but "bad" is a good start.