T&D Rockers - Very Minimal Clearance between Rocker and Retainer.

Wanted to post this diagram up that I just pulled down off Manton’s website, which is very instructive.
This is also what I’m seeing now in terms of movement across the valve tip.

565CamaroSS said:

No worries man. I’m grateful for the assist.
I understand what I need to do.
I just checked the intake again and it’s not .043, and without a different shim set I can’t get to that number. It’s closer to .035” as best I can measure it. That’s with a .040” shim under the intake stand.
On the exhaust without a shim and the lash cap on it, the gap between the tool and the rocker shaft is too big, something like .070. So I stuck a .040 shim under that stand and it’s pretty close to perfect at about .032 - 0.35.
It is a bitch to hold the valve up without a spring on it, whilst keeping the tool square against the valve stem and measuring the gap with a feeler gauge. But it looks like I’m getting there.
Thanks again for your help.

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Just for the sake of accuracy, I wanted to report in here that I did a very careful re-measurement of the rocker heights tonight. I discovered that the intake actually didn't have .035” of clearance between the tool and the rocker shaft with the .040” shim under the stand like I stated, but only close to .010”. I have no idea where I got that from. Maybe I confused the intake with the exhaust.

So, I took the shim out and bolted the intake stand directly to the head, and remeasured the gap and it came out to .046-0.050”, as measured with a mini feeler gauge. I made sure to keep the checker tool square and the intake valve up, so I’m sure that’s as accurate a measurement as anyone could get with the tool.

Then I put a checker spring on it, used a marker on the valve stem and rocked the valve open several times as close to the full lift as possible. I used a checker spring on it and measured the open height with a caliper. I took a picture of the pattern on the valve stem, and it looks pretty good to me:


So, it looks like the intake stands are actually pretty damn close to where they need to be without any shims under them, and I’m pretty sure that I’m going to install it without any shim under the intake stand. I’ll check the other head to make sure it’s the same.

Then on the exhaust, I decided that although I only have about .005” between the tool and the rocker shaft without any shim under the stand it, even though I need .033” of clearance, I would try it like that (without the lash cap) and use the Manton instructions to see where the roller sits on the valve stem at closed, mid-lift and full open.

The weird thing is that the sweep on it looks very close to what I’m seeing on the intake. So, although according to the T&D instructions, the stand “needs to be” lower, the sweep across the exhaust valve looks pretty damn good anyway (according to the Manton diagram). So, I’m wondering now if I shouldn’t run it like this or whether to use the lash caps and shim the stand to get the desired .033” clearance?

Here‘s where the roller tip sits with the valve fully closed:



And here’s where it is with the valve fully open ( I measured the open height with a digital caliper):


So, since I’ve ordered a bunch of shims, some .060 lash caps and the recessed locks, I’ll check the sweep again with the lash cap and some different shims once I get those things, to see if I can get as close as possible to the required .033”, but I’m pretty sure I could just bolt these damn exhaust stands on without any shims under them and let it eat without any problem.

bigblockmark said:

Permatex #2 nonhardening brown sealer in a tube works for rocker stud threads. Shelden at T&D has exchanged stands with me for $200 for special stands. Had to move rocker bolt positions up .040" to get pattern in center on valve stem before on Dart and AFR heads. Still offset left to side .030" on stems after that. Tuff to get done from out of 48 states? On shaft rockers pushrod length or lash caps should not be needed to get pattern correct. Stand height is all you need. Just measure for pushrod length after pattern is correct. Don't even need heads on block to do. With checking springs, just lift rocker thru sweep. I use red dry erase markers for checking pattern on stem. They don't supply less than .040" shims because they will deform under use according to Sheldon. The .080" shims can be ground on a magnetic base surface grinder to less thickness.

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Thanks for all of this. I read your thread on your struggle with setting up your rockers and what I have here is nothing compared to that, I think, lol.
After what I saw last night, I wondering whether the reason T&D don’t supply a wide range of shims like Jesel does is because stand height doesn’t change the contact pattern as much as you think.
I say that because on my exhaust valve, the contact pattern or “sweep” of the rocker tip is pretty much the same with the ~ .033” lower stand height (achieved with an .080” lash cap and a .040” shim) as it is with @ ~.005 ( you can barely see a gap) without the lash cap and with no shim.
I get it that you’re not supposed to use pushrod length with a shaft rocker setup, because the rocker height is fixed, whereas with a traditional rocker pushrod length can be used to change the geometry, since the pushrod itself, together with valve height is what holds the rocker in its position.
But I think there’s nothing wrong with using lash caps as a tool to change the valve stem length in order to set the geometry of the rocker shaft. In fact, that’s what Jesel’s instructions tell you to do if you can get the stand low enough.
I’m personally no fan of lash caps, simply because I’m paranoid about having tiny little pieces of metal inside an engine that aren’t fixed or “trapped” somehow. But the truth is that they are trapped and as long as a pushrod doesn’t bend or break or the adjuster doesn’t come loose, they really aren’t going anywhere, sort of like the needle bearings in the rocker fulcrum.
In any event, if I had Ti valves, I’d need to use them anyhow.
The positive thing about them that I see is that they create a wider contact patch for the roller and they protect the valve tip from wear, if that’s even a problem.
I have a set of Jesel shims on the way as well, which includes .025 and .050 shims, so that, along with a set of .060” thick lash caps, will give me the ability to set the rocker shaft height more precisely.
Once I see what that does with the rocker sweep/position, I’ll decide what to do.
Thanks again.

From my experience in dealing with 2 different sets of heads, old GM Bowtie, and Dart Pro 1, I would get confused, and frustrated. When I started to use a note book and wrote down every combination, and what the accurate measurements were with each thickness of shim supplied, it became clearer to me. Found it easier to only think of intake ONLY, then when it was right, ONLY exhaust. My intake stand is taller by .250 and my exhaust is taller by .125. My valves are intake +.250, exhaust are stock length, as required by Dart. I cannot understand, nor could Sheldon, why I needed the tall stands, but that is what was necessary for using the height tool supplied..
In speaking to Sheldon at T&D on different occasions, I gathered that the head manufacturers have sometimes moved the valves without notifying the rocker manufacturers. I know on the Darts I have, the exhaust valve is moved away from the intake by Dart by something like .040. This requires T&D to make an exhaust stand moved over by a like amount to center the roller right to left.
My combination on the Darts came out to be intake needed to be the shaft had to be .024 lower than the tool, with .040 shim it was .029 lower, off by .005.pattern very slightly to the outside of hole in lash cap. On the exhaust I needed the shaft to be .003 above the tool. With a .040 shim, it came out to be above the tool by.016. Off by .013. I found some shims in my extra junk that were .025 thick, so with those, the shaft seemed to be even with the tool, I couldn't get closer, that pattern is the same as intake, very slightly outside the hole in lash cap.
I've been running it this way since 2018, probably over 200, 250 runs, shift at 7400, and have been as high as 7800 at times when top end is slick, according to Computech EGT highest RPM..

I know the T&D rockers use a larger diameter shaft than Jesel does, so the Jesel tool will be off. I did my Darts with both heads on a table in the xtra bedroom, wife didn't care. It was still not fun, with all the combinations. I got one cylinder done on one head, then took the other head out the box, (mine were bare 355 CNC port), and noticed written on the head -005 in red marker. When I checked that setup it was slightly different than the first head, but I let er rip...One trick to keep in mind if head on the car, with all the plugs and PUSHRODS OUT, turn the crank till piston down maybe 20 to 25 degrees, take a piece of 1/4 inch rope and slide about 10 inches into the spark plug hole. It will coil up in the hole and then turn the crank again till it stops, Instant valve up holder! even pads the valve and dome for when you have to get violent!. When you're done with that cyl in. and ex., turn the crank backwards about the same, pull your rope out. Old country ass method, but don't tell anyone you did this, they tend to think less of ya.....
The reason I put the pushrod out, thought I'd be smart and just change the one spring in turning the crank to get the rope out, the other valve closed, pinched the rope, the rope nada coming out. Lesson learned.....until ya forget....

Wow. This thread sure changed directions.
Getting 90* geometry with shaft rockers is a challenge for sure, especially when they only give you either a .04 or .08 shim to work with...but that should also tell you something.
I haven't read the entire thread so forgive me if this is repeating something already said.
Rocker geometry is all about the relationship between the center of the rocker pivot (trunnion) and the valve tip and how much lift you have.
1) You NEVER use lash caps to correct geometry. That's not what they're for. At a minimum, you're just adding weight to your valve. Worst case, a hardened lash cap on a hardened valve tip is asking for a failure. Fix the problem right.
2) My rule of thumb for wear pattern location; if you're confident that your geometry is right and the pattern is in the center third of the valve tip, IMO you're golden. If not, you need to make some adjustments but don't compromise the geometry. if you feel you need to move the pattern front or back but your geometry is right, then order the rocker stands with the shaft moved one way or the other. Don't raise or lower the stand to change the location of the pattern unless the geometry requires it.

If you really want to get shaft rocker geometry spot on, you have to measure the sweep and adjust stand height till you get the least amount of sweep/narrowest pattern. This isn't easy. The little tool will work very well if you can use it precisely but that's almost impossible to do by yourself. If you can accurately measure from the top of the rocker shaft to the top of the valve, you can do some math and calculate what that dimension should be. For me, the easiest way is like I show in the pic below. I made a retainer that holds a dial indicator and reads the actual roller sweep on the valve tip. I use that in conjunction with measuring the lift to set my shaft rocker geometry. Using the method below, I set the sweep indicator at zero at zero lift. As I open the valve I watch the sweep indicator and it should reach max sweep at mid lift and then start back toward zero sweep asthe valve continues to open. At max lift the sweep indicator should go back to zero. That would be perfect 90* geometry...but it seldom happens. Depending on all the parts, a .04 shim will usually give me about a .010" difference in the sweep. If the sweep comes up short of zero at max lift, you add shim. If it goes past zero , you have to lower the stand. If I get the sweep to return within .005 of zero, I'm happy. At that point, you're picking pepper out of fly shit.
Once you get your geometry right, then you look at your sweep pattern. Again, IMO if it's in the center third of the valve tip, leave it alone. If not, then you either have to move it back or forward, but that shouldn't change the geometry. FYI, with ~.800"lift, I usually get right around .05 sweep on a BB Chev. One more FYI...Jesel does not build their rockers based on 90* geometry. You can't set a Jesel rocker like this. Reason being, the pushrod side geometry will be a mess. LOL...did I say pushrod side geometry?



I drew this years ago and it's been used all over the internet...gives you an idea of what you're shooting for;