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

5970 Views 97 Replies 10 Participants Last post by  565CamaroSS, 
565CamaroSS
2
Just setting up some 3128 T&D Rockers on my Brodix -3Xtra heads. I’m pretty sure I have the stands shimmed as close as I can get it to perfect.
But, the rockers look pretty damn close to the retainer to me. I realize that the rockers don’t move up and down like a regular rocker does on the stud when the pushrods flex at rpm, but I figure there must be some minimum clearance to keep the retainer from kissing the rocker body at high rpm, no?
Or am I being paranoid?
The pictures below might not be the best angle, but it’s not much more than what you can see there. Intake and exhaust respectively:
Automotive lighting Automotive design Automotive mirror Motor vehicle Automotive exhaust

Automotive tire Coil spring Tire Tread Automotive exhaust
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565CamaroSS
Yes, thanks very much for taking the time to explain in detail how it’s done. Very grateful for that.
I think your diagram confirms the Manton instructions as well, which dictate that roller tip starts on the “inboard side” (closer to rocker fulcrum) of the valve stem and as the valve opens, it moves outwards away from the fulcrum so that by mid-lift, it’s an equal distance across the center on the “outboard side” of the stem, then rolls back to where it started.
It’s very useful to know what the width of the sweep should be (0.050”) so many thanks for that.
The only reason I‘m considering lash caps on the exhaust valves is because I couldn’t get the exhaust stand low enough to meet the T&D instructions, which call for my exh rocker shaft to be .033” lower (.816“ lift) than the tip of the tool. So I added the lash caps to lengthen the valve and then shimmed the rocker stand to try to hit that number, and I can get real close to it (~0.035”) doing that.
But the strange thing is that I can’t see a better pattern doing that anyhow, although the lash cap is harder to read. But I’ve looked at this damn thing now until I’m cross-eyed, so I’m going to put it together with the recessed locks on the exhaust - so that I can use lash caps if I “need” to - but will use a test spring and roll the motor over until I can get a reading on the valve stem and see what that gives me.
Because at the end of the day, it’s where the roller meets the valve stem, and how much it moves across it that matters.
Thanks again for all the help.

Wait…”pushrod geometry“ you say??? JK, I’m confused enough as it is now, lol.
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scott foxwell
565CamaroSS said:
Yes, thanks very much for taking the time to explain in detail how it’s done. Very grateful for that.
I think your diagram confirms the Manton instructions as well, which dictate that roller tip starts on the “inboard side” (closer to rocker fulcrum) of the valve stem and as the valve opens, it moves outwards away from the fulcrum so that by mid-lift, it’s an equal distance across the center on the “outboard side” of the stem, then rolls back to where it started.
It’s very useful to know what the width of the sweep should be (0.050”) so many thanks for that.
The only reason I‘m considering lash caps on the exhaust valves is because I couldn’t get the exhaust stand low enough to meet the T&D instructions, which call for my exh rocker shaft to be .033” lower (.816“ lift) than the tip of the tool. So I added the lash caps to lengthen the valve and then shimmed the rocker stand to try to hit that number, and I can get real close to it (~0.035”) doing that.
But the strange thing is that I can’t see a better pattern doing that anyhow, although the lash cap is harder to read. But I’ve looked at this damn thing now until I’m cross-eyed, so I’m going to put it together with the recessed locks on the exhaust - so that I can use lash caps if I “need” to - but will use a test spring and roll the motor over until I can get a reading on the valve stem and see what that gives me.
Because at the end of the day, it’s where the roller meets the valve stem, and how much it moves across it that matters.
Thanks again for all the help.

Wait…”pushrod geometry“ you say??? JK, I’m confused enough as it is now, lol.
Click to expand...
All sounds like reasonable compromises and lets face it...an engine is nothing but a series of compromises. I would mill the stands myself and not use the lash cap.
Pushrod side geometry...yes...the pushrod side of the rocker needs to have the same geometry as the valve side to be "right". The imaginary c/l of the rocker on the pushrod side needs to be 90* to pushrod at mid lift. See if this makes any sense;
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This drawing makes perfect sense to me, makes it easy to understand what you are trying to achieve.
Scott, with the rocker adjuster being 1 turn down from full up make the pushrod end a true 90 degrees? Wait,.... I think it would only make the pushrod longer or shorter....or did I just get more confused?
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565CamaroSS
It makes sense to me as well.

I suppose the way to explain the need for it is if that 90*/90* relationship doesn’t exist, then you not going to get the lift from your cam that the lobe and rocker ratio predicts?

xlcr77, I was wondering the same thing. I’m thinking that if the adjuster is extended too much, it will lower the pivot point of the pushrod, so (in addition to starving the oil flow into the rocker), that will also adversely affect lift, no?
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scott foxwell
xlcr77 said:
This drawing makes perfect sense to me, makes it easy to understand what you are trying to achieve.
Scott, with the rocker adjuster being 1 turn down from full up make the pushrod end a true 90 degrees? Wait,.... I think it would only make the pushrod longer or shorter....or did I just get more confused?
Click to expand...
565CamaroSS said:
It makes sense to me as well.

I suppose the way to explain the need for it is if that 90*/90* relationship doesn’t exist, then you not going to get the lift from your cam that the lobe and rocker ratio predicts?

xlcr77, I was wondering the same thing. I’m thinking that if the adjuster is extended too much, it will lower the pivot point of the pushrod, so (in addition to starving the oil flow into the rocker), that will also adversely affect lift, no?
Click to expand...
What I see; moving the adjuster in or out can be a way to adjust pushrod-side geometry. The numerical ratio of the rocker is a function of the distance from the center of the cup to the center of the trunnion. If that changes, the ratio changes. Since we're working with linear vs radial movements here, it would be real hard to move the adjuster and not change the ratio (some) unless it was moving along a radius as well. So...saying that, the change in ratio is also very slight within the adjustment range of the adjuster. However, the change in geometry will be more obvious. A change in geometry can definitely effect how the information from the lobe is dictated to the valve. That's why all this geometry stuff is important and mid-lift, 90* geometry is, as well. We're trying to convert linear motion to radial motion, back to linear motion, with the least amount of lost movement or lost information. There is a horizontal element and a vertical element to the movement. On the valve side, we can see the horizontal movement in the sweep on the valve tip. When we optimize this, we get the least amount of horizontal movement (narrowest sweep) and the maximum vertical movement (lift). We work on the valve side because poor geometry can have really detrimental effects on the guides and possibly the valve and spring causing bad harmonics and we can easily enough address that but the pushrod side is another story. It can have detrimental effects as well if the geometry is whacked, but it's not necessarily going to wear parts out or cause other issues but it can definitely effect what the valve sees as far as timing of events. We have the same vertical vs horizontal movement we're trying to optimize for the same reasons.
LOL... and to top all this off, all this is static thinking, static checking. None of this takes into consideration what's going on dynamically although the Jesel rocker design does seem to address some dynamic issues.
Now multiply all this by 50-60 times a second or more. ;)
You can watch the movement of the pushrod side to see if it's close. Because the rocker is moving in a radial motion, the pushrod cup will "sweep" just like the roller tip and you basically want the same movement. It's an A-B-A movement and you also would like to see the adjuster and pushrod in-line with eachother at mid lift although that isn't 100% critical. The pushrod movement is.

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565CamaroSS
Thank you very much for this. This is brilliant stuff. I’ve learned more from you guys about valvetrain geometry and spring setup over the last few days than I’ve learned in the preceding 25 years.
This thread should be a sticky, sans all my bullshit questions, of course, LOL.
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565CamaroSS
BTW: At least I’ve gotten the valve springs sorted. I’ve stripped out the inner spring and installed the intakes at 2.03“ IH and the exhausts at ~2.02“.
They're not all absolutely perfectly the same height down to the last .0001”, but they’re all very close.
I verified that coil bind was actually at 1.10“ with the retainer on it.
I just got an LSM on-head valvespring seat pressure tester yesterday. Once I figure out how that works, I‘ll check and record the seat pressures on each one and make a record for future reference.
I checked about 5 springs in the vice with my little cheap proform tester and they were right around 300# at 2.02”.
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bigblockmark
Hope your LSM will work on your intake positions. Some heads it won't clear the valve cover rails with the rocker at lash position.
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565CamaroSS
bigblockmark said:
Hope your LSM will work on your intake positions. Some heads it won't clear the valve cover rails with the rocker at lash position.
Click to expand...
Good to know. I hope it works too. Will try it later and report back.
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One thing to keep in mind if you use a LSM valve spring checker. When you hook the checker onto the rocker, make sure the line on the roller of the checker is centered on the middle of the rocker C/L. I've found the reading is off a little if it's not centered.
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565CamaroSS
Thanks. I’ll try to figure out how to use it properly, lol.
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565CamaroSS
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Don’t want to make this thread any more overbearing than it is already with all my “mental masturbation” on this topic, lol, but just want to update the thread.

I had already decided I wouldn’t use any shims or the intakes, since they’re damn close to perfect (the intake stand is only about .007” too low), but I’ve been agonizing over not getting the exhaust closer to the ideal (.033” lower) measurement with the tool.

I’ve now decided to use both sets of stands without any shims, even though according to my measurement with the dinky little T&D tool, the exhaust is about .025” too high.

Here’s why I’ve decided that:

After dicking around with the lash caps, I was reminded why I had an unused set of them and about 5 different sets of unused pushrods in storage, from 15 or so years ago when I was setting up the stud/roller rocker valvetrain on the 540 in my old boat. I HATE those damn little things, because it doesn’t take anything for one if them to get loose and bounce around and end up in the motor. The second time I dropped one of those, I decided to forget about them.
I know that Manley makes some high-priced “snap-on” lash caps, but I think I’ve invested too much in spare parts on this deal already.

Here’s the thing, I can’t really see any significant difference in sweep on the exhaust with the .080“ caps and a .060 shim, which gives me a gap close to the T&D spec (.033”) between the tool and the rocker fulcrum, vs. using no lash cap and no shim. Mind you, it’s next to impossible to see any discernible sweep on the lash cap anyhow, since they’re too dark to see shit on, using any colour marker.

Here’s what the exhaust sweep pattern looks like, sans shim and lash cap:
Automotive tire Gas Auto part Rim Camera lens


I’ve also checked the seat pressure on my springs using my fancy new LSM tool and according to that, the seat pressure on the intake is right around 320# with the inner spring stripped out @ 2.03” IH:
Automotive tire Bicycle tire Automotive lighting Gauge Motor vehicle


Big thanks again to everyone for your invaluable advice on this.
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565CamaroSS said:
Don’t want to make this thread any more overbearing than it is already with all my “mental masturbation” on this topic, lol, but just want to update the thread.

I had already decided I wouldn’t use any shims or the intakes, since they’re damn close to perfect (the intake stand is only about .007” too low), but I’ve been agonizing over not getting the exhaust closer to the ideal (.033” lower) measurement with the tool.

I’ve now decided to use both sets of stands without any shims, even though according to my measurement with the dinky little T&D tool, the exhaust is about .025” too high.

Here’s why I’ve decided that:

After dicking around with the lash caps, I was reminded why I had an unused set of them and about 5 different sets of unused pushrods in storage, from 15 or so years ago when I was setting up the stud/roller rocker valvetrain on the 540 in my old boat. I HATE those damn little things, because it doesn’t take anything for one if them to get loose and bounce around and end up in the motor. The second time I dropped one of those, I decided to forget about them.
I know that Manley makes some high-priced “snap-on” lash caps, but I think I’ve invested too much in spare parts on this deal already.

Here’s the thing, I can’t really see any significant difference in sweep on the exhaust with the .080“ caps and a .060 shim, which gives me a gap close to the T&D spec (.033”) between the tool and the rocker fulcrum, vs. using no lash cap and no shim. Mind you, it’s next to impossible to see any discernible sweep on the lash cap anyhow, since they’re too dark to see shit on, using any colour marker.

Here’s what the exhaust sweep pattern looks like, sans shim and lash cap:
View attachment 449313

I’ve also checked the seat pressure on my springs using my fancy new LSM tool and according to that, the seat pressure on the intake is right around 320# with the inner spring stripped out @ 2.03” IH:
View attachment 449314

Big thanks again to everyone for your invaluable advice on this.
Click to expand...
That pattern looks good to me as well, get that this running and FOG the shit out of it with the new N20 setup
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565CamaroSS
Saviour68 said:
That pattern looks good to me as well, get that this running and FOG the shit out of it with the new N20 setup
Click to expand...
LOL. That's the plan.
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565CamaroSS
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Just an update, after carefully measuring the length pushrods I needed, I ordered a set of 5 series pushrods from Manton: 9.24” length 7/16” dia with .120“ wall for the exhaust and 8.25” length 7/16 - 3/8“ single taper with .120” for the intake.
They’re not cheap (~$530 - plus $77 shipping and 25% import tax for the set), but I believe they’re more than strong enough for what I’m building. They almost look too good to put inside a motor.
Manton turned them around and shipped them out inside of 4 days too.
Office supplies Wood Writing implement Tints and shades Electric blue


I installed them and cold-lashed the rockers at .020 for the intake and .022 for the exhaust (cam sheet calls for .024 and .026 respectively. I’ll probably reset the lash hot once I’ve got the engine running.

The pushrods clear the heads nicely, thanks to the offset location of the set screws on the intake rockers:
Automotive tire Motor vehicle Gas Automotive exterior Engineering


Ready to button this sumbitch up and will drop it in the car soon:
Wheel Tire Hood Automotive tire Motor vehicle


Thanks again to everyone who offered their advice. Much appreciated.
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565CamaroSS said:
Just an update, after carefully measuring the length pushrods I needed, I ordered a set of 5 series pushrods from Manton: 9.24” length 7/16” dia with .120“ wall for the exhaust and 8.25” length 7/16 - 3/8“ single taper with .120” for the intake.
They’re not cheap (~$530 - plus $77 shipping and 25% import tax for the set), but I believe they’re more than strong enough for what I’m building. They almost look too good to put inside a motor.
Manton turned them around and shipped them out inside of 4 days too.
View attachment 451917

I installed them and cold-lashed the rockers at .020 for the intake and .022 for the exhaust (cam sheet calls for .024 and .026 respectively. I’ll probably reset the lash hot once I’ve got the engine running.

The pushrods clear the heads nicely, thanks to the offset location of the set screws on the intake rockers:
View attachment 451925

Ready to button this sumbitch up and will drop it in the car soon:
View attachment 451923

Thanks again to everyone who offered their advice. Much appreciated.
Click to expand...
Looks good, can't wait to see what she does.
Its always better when you put the hard work in and do things yourself.
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scott foxwell
565CamaroSS said:
I installed them and cold-lashed the rockers at .020 for the intake and .022 for the exhaust (cam sheet calls for .024 and .026 respectively. I’ll probably reset the lash hot once I’ve got the engine running.
Click to expand...
Good job! Looks great.
Just FYI, I would do .018/.020 cold. Those heads will grow ~.006" from cold to hot.
Keep up the good work!
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565CamaroSS
scott foxwell said:
Good job! Looks great.
Just FYI, I would do .018/.020 cold. Those heads will grow ~.006" from cold to hot.
Keep up the good work!
Click to expand...
Thanks Scott. I was on the fence about whether to set cold lash .004 or .006” tighter, and decided to err on the looser side.
I’ll take my time and do them all over at 0.018 and 0.020. Might leave them at that too. I can always check them hot after I get it running to see if they’re on spec.
Thanks again for taking the time to help me out, man. You guys are the people that make this forum great.
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