I for one want to say I appreciate your efforts.

oops!

 

I use checker springs and the adjustable pushrod. I watch the roller on the tip of the valve, if in a complete turn of the engine the roller travels equal on one side of the valve tip centerline as the other and at half lift the rocker looks to be near 90 degs I call it day. I do it all by eye on some expensive pieces. Good video though

 

That's pretty much how i do it except i use sharpie on the top of the valve stem to witness mark the travel and bought a checker that you slide down the rocker stud and and rest on the valve and use the adjustable push rod to make contact.

oops!

 

Shaft rockers with the adjustment at the pushrod end might be a special case because the rocker bearing does not move, I think you can extend out the pushrod for preload if the regular valve springs are on or add an allowance for the preload to the measured length if you have checker springs on.

 

Yes you are probably right, the checker spring won't be able to push the rocker back in position because the internal spring in the lifter is stronger than the checker spring!
But then the video is wrong

 

That's the logic I was using. Not exactly sure what you mean about the video being wrong. It was dealing with the trunnion on the stud, whereas the shaft mount have the bearing fixed on a perch using the stud hole. I didn't read Chris's post about adding 0.050" for the preload until after I wrote the post you are commenting on, but Chris's comment implies that maybe he would be adding some additional length as allowance for lash on solids and preload on hydraulic applications.

 

You use shims under the shaft rocker stands to get the proper geometry, T&D also sends you a little height gauge so you get it perfect.

 

What kind of tolerance range are we talking here? What happens if you are in the ballpark but off by maybe .150 - .250" as this case might suggest. That sounds like a lot to me...

 

Hello Wayne,

I've got the T&D set-up and the pedestals are shim-equipped based on the gauge. I had the shaft rockers from a previous engine and got a new gauge and shim set from T&D, since I didn't set it up the first time on the other engine.

 

I want my valve guides to last a long time......I don't give a crap about this " mid lift 90 degree " mumbo jumbo......I'll keep using my marking compound on the valve tip looking for a minimum centered contact pattern......you do it your way run the motor for 25000 miles and then we can pull our valve springs and do the C6 Z06 wiggle test....if your pattern isn't good and centered...I'll win!

 

I am by no means an expert on this topic but I have spoken to someone who is…my builder for the bottom end of my L-82 355. This guy is relatively young and has LOTS of experiencing in this area and a footnote to SolidLT1, my builder recently wrote a technical article in one of the automotive trade publications on the Z06 wiggle test (he checked mine recently-all good). He has a fix that he uses to correct the cylinder head issue with the Z06 valves. He KNOWS what he is doing….and its published.

He was very clear and specific with advice when I did the roller cam and pushrod checking… witness mark/observation-check more than twice..good to go. Unless the engine is going beyond 6,500+ RPM, the rest is totally unnecessary for a street engine. This reminds of the cam button issue….way overly complicated

 

With a roller tip rocker, side loading is minimal as the roller tip 'rolls' across the valve tip vice a regular rocker tip that 'slides' across the valve tip resulting in side loading of the valve stem and hence, wear on the valve guide. When I converted to a Howards retro HRC, I also used their hydraulic rollers and their suggested push rods for the retro HRC conversion. The length was 7.15" or 7.144". Anyway, I installed a push rod and lo and behold, it was dead on using the sharpie test method. Car runs fine with no unusual sounds coming from the engine.

 

And some believe that the adjuster is used to make up for pushrod length. This is NOT correct. The adjuster should NEVER be more that 1.5 turns OUT.

 

We have a set of AFR 335 here with "Centered" pushrod swipes. Engine has about 5 hours of run time on it, 1 hour of that is idle time in his garage trying to line out an EFI system. The engine suffered from in correct pushrod length and fuel wash during this time. 16 new guides x $12 and $150 to install and hone new guides.

I would suggest doing it your way then trying this way and see what you come up with. I learn everyday in this industry...that's part of the fun I have.

 

Exactly my experience with Howards retro roller cam and the length-rockers are comp cams 1.52 roller tipped-7.15 pushrod length….

 

Good morning guys. I've been asked to come on here and here and help clear up some confusion on this subject and I'll start by responding to this post because it's the most widely repeated method, the probably the most incorrect.

First, also, let me address the lash/preload issue since admittedly it was an oversight on my part to not mention it in the video. We'll try and add an edit to correct that and get the info included.
Regarding solid roller lash...you need to subtract the amount of lash from the gross lift number on your cam card, then divide that by two in order to get your half-lift number.
With hyd lifters, I recommend following the video to determine your pushrod length, then add whatever your preload will be to that number. If you come up with a 7.150 pushrod length, and you're using one full turn on a 7/16 rocker stud, then add .05", so your final pushrod length would be 7.20". If you're using 1/4 turn, then add .025", and so on. If you have a 3/8 stud, then you have ~.042" per turn of preload, so figure that.
Cam should be on the base circle for all of this.

Now, regarding the below mentioned method of finding pusrod length; if you follow this method I guarantee your pushrods will be too short by a significant amount.
Proper roller tip movement or "sweep" across the valve when your geometry is correct will be the following:
The roller should begin moving away from the rocker stud as the valve begins to open. Lets say it starts at zero. At mid lift, when the rocker is 90* to the valve, it should be at it's furthest point of travel. As the rocker moves past half lift, the roller should stop and change direction and begin moving back toward the rocker stud, and at full lift it should be right back at zero where it started.

Here's a little diagram I did a while back. You can see that when the rocker is at 90* to the valve at mid lift, there is an equal amount of rocker travel (arc) above mid lift, and below mid lift. Also note the travel of the roller tip. This is ideal rocker geometry on the valve side of the rocker. The method mentioned below won't get you even remotely close to this, will result in terrible rocker geometry, promote excessive guide wear and unwanted harmonics in you valve train and show a loss of power.

 

The critical part of this method is getting the initial 90* relationship correct. That's why I stresses that several times. Once you do that, the rest is simple math. There is no real reason to roll the engine over to check this. It doesn't hurt, but it's not necessary if you follow the steps.

 

I'll take that challenge any day of the week, and for the pink on your Z06, or whatever you drive. I guuarantee the OEM's use the mid lift engineering on thier valve train. They design it so that the wear pattern is centered on the valve tip since that's ideal, but the 90* geometry is the critical design. Anything other than that will cause more side loading on the valve stem than not having the pattern perfectly centered. If you're using the location of the wear pattern on the valve tip to set your pushrod length without cehecking 90* geometry, I can just about guarantee your pushrods are the wrong length.

 

Hi Super6. Thanks for teh questions.
I addressed lash/preload in my first post, but since you asked, I'll address it again. I will admit that this was an oversight on my part in the video, not mentioning these. Hopefuolly we can get an edit in there to add the information.
On lash; you need to subtract the lash from your gross valve lift before you start. This will give you your net valve lift. This is the amount the valve will actually open. Once you have that, then divide that by two, and use that for your half-lift number.
On hyd. lifters, I don't figure preload into the geometry because it will change the geometry. Simply follow the video and add the amount of preload to the final pushrod length.
All of this is done with the cam on the base circle. If everything is done correctly, the rocker will (should) be perpendicular to the valve stem at mid lift. That is what we are trying to accomplish here.
With after-market heads and stud mount rockers, the sweep pattern is usually not going to be in the center of the valve tip. This is because of the heads having longer valves and more spring installed height for bigger lift cams. The angle of the valve and the angle of the rocker stud are converging...they are pointing at each other, so the higher up you go on either (or both) the closer they get to each other but the rocker stays the same length. As I said before, it's less important to have the pattern centered than it is to have the proper geometry, of course within reason. I use the center third pf the valve tip...if the wear pattern is in that center third, I'm happy.

 

Yes, exactly.