SBC push rod checker?
 

i read the entire discussion about push rod lengths. all very interesting.
so i want to know your thoughts on the push rod length checker [manley or proform].
what is the correct way to use this and what are the secrets to success using this checker?
thanks rod in AZ

Re: SBC push rod checker?
 

If you're talking about the old red plastic "tool" that slips over the rocker stud, the best way to use one of those is to use it to take up space somewhere out of the way.

What you need is an adjustable pushrod length checker, Comp Cams has them. Use that on your engine, either mocked up completely (head gasket thickness included) or assembled, combined with a dial indicator that you can use to read valve lift at the retainer. Adjust the pushrod length checker until you get the correct lift and geometry for each valve and each lobe. Measure the over all length of the pushrod checker with a dial caliper, and order the correct pushrod. Thicker wall and larger diameter is better.

Re: SBC push rod checker?
 

What most of the checkers that you see or saw on the market dealt with trying to get the rocker arm in the middle of the valve. At that time, most people thought that was the best rocker arm geometry. Today, we know that is not true. You may end up with a rocker in the middle of the valve, but you just got lucky. In today's racing mode with angle milling heads and moving of valve guides even slightly, being in the middle of the valve is damn lucky. And also what contributes even more to this is the accuracy or lack of, is the rocker geometry. The short side of the rocker could be accurate and the long side could be long or short or vice versa. So you may could never get the valve in the middle.
reed

Re: SBC push rod checker?
 

Alan, I have just been working through this on my BB chev stocker, but after reading the previous thread am not so sure I'm correct in looking at just correcting the spec lift at the valve by lengthening the pushrods. I noticed that the longer pushrods create a wider "swipe" pattern on the valve stem, even as the lift is increasing at the valve. In my case, my cam lobe lift is .240" so would theoretically produce .408" at the valve with a 1.7 rocker. In fact, with light checking springs it was more like .420", way over spec. With a race spring and the same .120 wall pushrod, valve lift dropped into the low .380" range, to my thinking a huge difference. After installing a .100" longer pushrod, lift increased into the upper .380's, still way short of my legal max at .398".
The rockers are the re-inforced Holroyd units w/ his oversize studs, so hard to imagine that kind of deflection mainly in the rocker body, but these are the numbers I've been seeing. I'm now questioning whether the objective might not be to achieve the narrowest contact pattern on the stem tip, thus minimum side thrust and drag, then consider grinding even more lobe lift into the cam? Another poster suggested that, if I understood him correctly, that the pushrod tip and valve stem tip should each be at 90 degrees to the rocker stud and in line with each other with the lobe and valve both at half lift. I'd like to hear more feedback on those points from anyone who's researched this topic. I'm an old dog, but still tryin' to learn a few new tricks. Thanks to all who are contributing to this interesting subject!
Grant Eldridge
E/SA 6650

Re: SBC push rod checker?
 

Grant says
" I'm now questioning whether the objective might not be to achieve the narrowest contact pattern on the stem tip, thus minimum side thrust and drag, then consider grinding even more lobe lift into the cam? "
Bingo, you got it...

Re: SBC push rod checker?
 

The correct rocker arm geometry WILL result in the least amount of swipe across the valve. Setting the correct lift is not getting the correct rocker arm geometry. You can check for correct rocker arm geometry without even having springs on the head but do use the checker push rod to get you the correct length. But remember that is the correct length unloaded. Some where along the line, you will need to assemble the head to get the correct length LOADED. The length doesnt change, but when loaded, the pushrod may no longer be that length.
reed

Re: SBC push rod checker?
 

The only problem with the idea of altering lobe lift is this: If you alter your valvetrain geometry so that you reduce the lobe lift necessary to achieve near maximum lift, you may change your rocker arm ratio so that it is outside the legal limit for your particular engine.

This can go either way. You could end up needing more lobe lift, meaning your rocker arm ratio has been effectively reduced at maximum lift. However, you could also end up needing less lobe lift, because you have eliminated lost motion, and effectively increased your rocker arm ratio. As far as I've read, and from the answers I've been given, if you end up with less than maximum rocker arm ratio, and needing more lobe lift, you are technically legal. If, on the other hand, you end up needing less lobe lift, because you end up above the maximum rocker arm ratio, you are illegal, even though you have legal rocker arms.

For example, let's say you are allowed 0.520" lift, using the rectangle port solid lifter big block Chevy cam engines. You're allowed a 1.7:1 rocker arm ratio, according to the blueprint spec, and your lobe lift will be approximately 0.306". Suppose you correct your geometry, and eliminate the scrubbing and thrust caused by lost motion, so that 0.306" lobe lift yields 0.540" at the valve. You have effectively increased your rocker arm ratio, even though you have not changed the rocker arm. So, your rocker ratio at max lift is now 1.76:1. You now need a 0.295" lobe lift, to get your valve lift down to 0.520". We'll ignore the fact that you really want it around 0.515" so that you're safe going through tech.

The problem is, if you go back and read NHRA Division 3 tech guru Travis Miller's posts, is that NHRA is not going to like your new effective rocker ratio, since it now exceeds 1.7:1, the maximum allowed.

Now, you might get through "basic tech" where they pop a valve cover or two off and check lift at the valve, but if they check lift at the valve and lift at the lobe, or even the end of the pushrod, and do the math, guys like Travis are known to do so, you may fail tech.

A rocker arm is not a constant ratio device, it is a constantly variable ratio device, the ratio changes as you move through the lift curve. You alter that ratio as you change pushrod length and or valve length, and the relationship between them, as well as where the rocker arm is on the stud when valve lash is adjusted.

Yes, as Bub stated in reply to Grant, getting the scrubbing and the thrust to a minimum, thereby reducing the force necessary to open the valves, is what you want. However, in Stock Eliminator, if you substantially alter the rocker ratio in the process, you can find yourself in an unhappy situation in the tech barn.

Remember, when you change camshafts, you may or may not get the same exact base circle, if you do not, you will have to start all over again. You will also find that your cam grinder may not have the lobe design you need with the lift you want. Now, if they use a CNC grinder, they may be able to easily go in and change the lobe lift. However, in doing so, they may alter the lobe design. If their Stock Eliminator cams are ground from masters, or they are unwilling to write a new CNC program, you may be stuck. This is where you need a really good relationship with your cam grinder. Adding or subtracting a few thousandths of an inch of lobe lift is not nearly as simple and easy as changing deck height or pushrod length.

Re: SBC push rod checker?
 

A few years ago, my pushrod length was off and I had to come up with something to make it easy for me to believe. My guy at the time said you could mark the valve stem and measure how far it walked across the valve stem and try to make it the minimum distance. I ended up making a dial indicator that was mounted on the valve retainer, and have the tip of the indicator against the center of the roller tip. It would measure how far it swept across the stem and I would have a number for a certain length pushrod. You change the length of the the pushrod and it changes how far it swept. Made it real easy. This was on stud mounted rockers. I picked up considerable et, and everything seemed to work. Now I got new heads with the valve cover rail real high and I can't use that tool for these heads. But I got my video camera and used it to look at the movement across the valve with different length pushrods and made my length off of what I seen in the video. i have seen a advertisement a few years back and it was called Off Your Rocker, and he sold a package with for a dial indicator that basically did the same thing. I am no expert, but I have seen other people ask mne what I did to drop the et and they ended up using it to find out where they were. Just think about what you are trying to do. I had to put in a lot longer pushrod and then put head washers under the rocker stud to get it up where it needed to be. It is fun when you can see the change.:)

Re: SBC push rod checker?
 

First lets make sure that we understand. You cannot make the rocker arm have any more rocker ratio than what it is. If it is a 1.7 then it is 1.7. None more nor non less. If you want to delay the full ratio to come in later in the lift, then yes you can have the cam read too large on lift, but only if the cam is GROUND wrongly to start with. By wrongly, I mean it was not ground correctly to start with to get minimum scrub pattern and minimum friction losses thru out the variable ratio of the rocker arm. The cam grinder ground it to have the pushrod some length other than perfect use of the rocker geometry. Is that what you want? I dont know any good cam company today that doesnt use a CNC cam grinder some place in their facility. And believe me they can repeat within a couple of tenths of a thousands. I have worked in a facility that would grind a 100,000 shafts per week and hold +/- .0002 per shaft. That camshaft will be much closer in tolerance than you will ever be able to measure. If you want the camshaft to your spec, they can grind it. If they cannot, why are you purchasing from them? One thing I do know, you never ever get what you do not pay for. If they cannot hold the accuracy, whether it be master or CNC, on one lobe, then what makes you believe that all 16 lobes are exact. No matter what push rod length you have, the lobe has to be correct to start with and no matter what lift you have, YOU want to get to that lift with the least amount of frictional losses available. TO ME any thing else is unacceptable.
Damn here i go again on my .02 cents worth. Geez I sorry
reed

Re: SBC push rod checker?
 

Bud you have a PM. Thanks.

Re: SBC push rod checker?
 

Well, here I am at 6:07 AM on a Monday reading this. Here's two more cents. Since most of these stocker cams are ground with more precision and consistancy as to lobe lift and profile, which can be verified by checking all 16 lobes with the cam in the block, then the places correction is necessary would be in the rest of the valvetrain. If all 16 lifters check,then the pushrods, rocker arms, and the valve stem lengths have to be considered. The post regarding minimizing the sweep of the tip of the rocker arm across the tip of the stem revealed the secret to minimizing valve train friction, that sounds like the optimum goal. Variations in rocker arm ratio and valve seat depth and variations in stem length are the only variables left to play with. The actual ratio of rocker arms vs. effective ratio is one more thing to concern yourself with. Seems like these two threads have revealed more areas of thought to be considered than anything else I've seen in a long time.Yes, push rod length is more critical than most persons have probably thought.

Re: SBC push rod checker?
 

I was told by an engine builder that if you have your geometry right ,this will give you maximum lift. Would anyone have any info on how much lift is lost through hydraulic lifters due to spring pressures at race rpms. Thanks, Pat.

Re: SBC push rod checker?
 

Greg
Several years ago, I made myself a rocker ratio checker. It is simple. Take a flat piece of metal and install a stud. Really needs to be what ever stud diameter your rocker system. Since I was using a small block chevy, I used a 5/16 steel ball out of a roller bearing. I then placed this on top of a gage block. It seemed easy to put 1 inch lift on small side of rocker ratio was easiest to use. I then put a dial indicator on the large ratio side. You can then measure the correct ratio of the larger side. I then went thru every stamped rocker arm I could find. I then put 8 together for the intake and 8 more for exhaust. All as close to each other as I could get. While doing this, for my stock rockers, I decided to check some roller rockers that I had (used-couldnt afford new ones). Man was I ever surprised at what I found. You have to remember this was several years ago and I found out later that some companies was still repeating the wrong way to build a rocker arm. I had no idea what was wrong but I knew it was wrong or the rockers did not make 1.5 (SBC). I was at one of the first PRI shows in Nashville, Tenn and I went to a presentation by Smokey Yunick. I waited until after his presentation and asked him. His comment was " Damn son, dont you know that cause it is new does not mean it is right" He then splained the world too me in a language that embarrassed me then. I came back and got a set of rockers (used)like he told me to get and they checked all the way thru a rotation. Apparently, people like he and Bill Jenkins new this but I had no clue.
reed

Re: SBC push rod checker?
 

I had already signed off and went to balancing a crankshaft but I would like to take a second to expound on this. I will never tell you this is correct but I BELIEVE it to be so. If you measure and set the correct rocker ratio, you will always have the smallest swipe pattern across the valve. Yes you can set rocker ratio by measuring the swipe pattern but that length is the result of correct ratio so why not set the correct ratio to start with, but proper ratio can be measured and attained by several methods. Choose your poison
reed

Re: SBC push rod checker?
 

It's Bub... BUB

Re: SBC push rod checker?
 

Sorry about that Bub...

Re: SBC push rod checker?
 

I'm surprised that no one has meentioned grinding the rocker arm tip. . .
If roller rockers are accepted next year, this discussion expands arithmetically.

Re: SBC push rod checker?
 

Long ago stocker racer here, I still like the idea of putting my mechanical
knowledge or lack there of to the test. Years back my co engine builder
and I were trying to work thru some of these exact same problems.
We had a couple of coffee cans of CHEVY SB rocker arms and were
testing them on a base engine. Then we started to grind them and we were told by some smarter, older guys that it wasnt a good idea to grind rocker arms because the rocker tips were only hardened a few thousands into the metal and once you got past that point you would chew through them very quickly,So unfortunately we stopped working in that area,. Anyway this subject lends itself to a real cause and effect
senario. I dont think I have to worry about setting a record and being in a tear down barn anytime soon,but I think one of the main subjects of this thread is, how do the tech guys check cam lift and is there consistency from division to division. If I was currently racing that is something that I
would like to get established so when I built my motor during the off season ,I could build it and check my cam lift just like the tech inspectors were going to do in the new season. ed

Re: SBC push rod checker?
 

Dwight
Grinding a rocker tip has been done several times by such people as Smokey. And yes I have been following the thread on roller rockers. I know this may be the easiest and cheapest way out for many racers BUT I have a big big problem with this. I get upset when I hear people talk about the amount of technology and development that has been put into Pro Stock, Top Fuel and all our pro classes. But do you know what I feel is the most technological advanced class in racing today. NASCAR was included in that short list but no longer. Stock Eliminator is the most advanced. Think about how many people and for how many years have racers and engine builders been tweaking on stock parts to make things more frictionless , more advanced than they were ever intended to be. Sure the cost went with that but this is what has made the class what it is today. Look at how much science has just been discussed on rocker arms here on this forum and now we want to take that advancement all away and turn it over to vendors and let them just build us a set of roller rockers. Look at how many parts we have scienced out and now turned over to vendors to capitalized on. Let NHRA and NASCAR leave us alone and we will find a way to make it better. It is no longer race on Sunday and sale on Monday. Every month stock eliminator gets closer to being a Super Stock. Leave the parts alone and stop the cheating. Let us as racers tweak and build the best we can. Let us accel in developing our rides and our power plants and receive the fruits of our labor and OUR ingenuity not some damn vendor that wants to do nothing but make money off us. If we break it enough, we WILL make it better. Let US play in our sport and be the best not some vendor for hire. If we can make our one part better and we are faster, great that is what makes our labor of sweat and tears worth that extra .1 on Sunday and then I go home and try to beat your .1 for the next Sunday. Let us use OUR brains not them.
Damn got on a rampage already this early. Woman come git me off here whilst I am aspoutin
reed

Re: SBC push rod checker?
 

Reed, I am very new to this site,but I really have enjoyed listening to
what everyone has to say regarding their class" stock eliminator".
I also read what you had to say about the large amounts of knowledge
thats posessed within the stock class . If we were to state that
we had more or equal knowledge of engine design and theory to the folks at the NASCAR shops of Hendrix and Rousch we might get a few
funny looks,with that said, I strongly believe the people in Stock Eliminator do more with less than any other class hands down. ed

Re: SBC push rod checker?
 

[QUOTE=eddie c;290895]Reed, I am very new to this site,but I really have enjoyed listening to
what everyone has to say regarding their class" stock eliminator".
I also read what you had to say about the large amounts of knowledge
thats posessed within the stock class . If we were to state that
we had more or equal knowledge of engine design and theory to the folks at the NASCAR shops of Hendrix and Rousch we might get a few
funny looks,with that said, I strongly believe the people in Stock Eliminator do more with less than any other class hands down. ed[/QUOTE


Eddie
What I am talking about when I reference NASCAR is that none of those engines are no longer "stock". They are all race bred and have nothing to do with a stock car. They are tweaking and changing something that we cannot even purchase. It most definitely is not race on Sunday and sale/purchase on Monday. There is no longer a Chevy, Ford, or Mopar. It is what NASCAR has allowed the sport to grow and evolve too. It has even evolved further than our on Super Stock, so for me to say they are ahead of us on technology is just like saying Pro Stock and Top Fuel and our on pro categories is ahead of us. All of these categories have clearly a different playing field with totally different rules. They are allowed to take something and totally make it from scratch. We have to work with what we have and make it better. They make better what ever they have today. Tomorrow, they may have something entirely new to work with. We still are improving the 350 SBC or the 427FE Ford. So yes, I firmly believe we are the best at what we do and guess what, if NHRA doesnt stop letting us substitute new parts, we will either be another Super Stock class or another NASCAR. That 67 Ford will be nothing but a 67 Body going down the track with all modern parts under the hood. No technology, just purchased parts.
Damn come git me woman, I am aspouting agin
reed