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Discussion Starter · #1 ·
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:
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Discussion Starter · #3 · (Edited)
Cam specs are 286/300 @ .050”, .836”/.816”. Pretty sure I need a triple spring for that.
To use lash caps I would have to change the locks (which isn’t a big issue) but I will most likely need a new set of stands from T&D, or at least some longer bolts, since I’m using a thin (.040”) and thick (.080”) shim under the intake stand as is.
 

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I have T&D rocker stands also, but with Dart 355 cc heads, and triple springs.. I would not use the taller stands, unless you have taller valves than what the heads were manufactured for. The taller stand brings roller alignment with the valve problems. Same goes for lash caps, unless you have Ti valves. The little tool supplied with your set gets you your correct height. With a .040 and a .080 shim, you are raising the stand .120. There are .125 taller and .250 taller stands available. They swap out stands, as long as the engine has not been run. Your best bet is to call Sheldon @ T&D. Taller stands do not automatically mean longer stand bolts, as the taller stands are raised in the area above the bolt.
Make SURE you are using the absolute longest stand bolts your heads allow without bottoming out in head. With triple springs you want as much thread attachment as possible. They have many different length bolts available for this.
Advise you print their Parts page for reference as to what's available in bolts, but stand bolts must be flanged style.
I'd measure the retainer clearance with a wire gauge before you call Sheldon. Have exact information written down before you call.
 

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Looks like you have +.05 locks. Are these longer valves than came with the heads?
You don't need any where near a triple spring but that's another subject.
How are you setting up the stand height? Stand height dictates rocker geometry and rocker geometry is all that matters. It looks to me like you need more shim...more stand height but that may not be the case. Use the tool and follow the instructions to the T. Don't "guess". Do NOT use lash caps to correct a geometry issue.
 

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Cam specs are 286/300 @ .050”, .836”/.816”. Pretty sure I need a triple spring for that.
To use lash caps I would have to change the locks (which isn’t a big issue) but I will most likely need a new set of stands from T&D, or at least some longer bolts, since I’m using a thin (.040”) and thick (.080”) shim under the intake stand as is.
I run 9000 rpm, 1200 lbs open with .950" lift with a small diameter PAC dual spring.
 
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Discussion Starter · #7 ·
Thanks guys. I’ve read and re-read the T&D instructions to the letter, as well as anything else I could get my hands on. My kit came with the .750” tool, so I followed the instructions and subtracted half the difference between .750” and the lift on the intake and exhaust, respectively, from the required amount of shim. That’s my understanding of what you need to do, based on the instructions, which leave a lot to be desired, tbh.
I had to make do with the shims I had, which were only .080” and .040”, so I’m not saying it has precisely the right amount of shim, although I was pleasantly surprised that it was close.
I’ll post up the numbers later, as I wrote them down but left them in the garage.
 

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Discussion Starter · #8 ·
Looks like you have +.05 locks. Are these longer valves than came with the heads?
You don't need any where near a triple spring but that's another subject.
How are you setting up the stand height? Stand height dictates rocker geometry and rocker geometry is all that matters. It looks to me like you need more shim...more stand height but that may not be the case. Use the tool and follow the instructions to the T. Don't "guess". Do NOT use lash caps to correct a geometry issue.
Thanks for your advice.
I’m not sure what locks I have. Those are the same locks and retainers that came on those heads when I bought my original motor from Shafiroff in ‘08. The springs are new CC #948 springs, which I ASSumed I needed, since that’s what came on those heads as well.
I’m happy to change the springs and retainers, if someone can tell me what would work with those specs?
The valves are longer than stock Chevy length valves: the intakes are +.350” and the exhaust .100”, iirc. Spring installed height is 2.10”, as specified, and that required the intake springs to be shimmed, but not the exhaust, which were all very close to 2.10”
I did follow the instructions supplied by T&D, and I did use the tool they sent, which was the .750”, although as I said, I couldn’t get the exact height I needed, as the kit only came with two thickness of shim (.080” and .040”).
I really have no intention of using valve lash caps.
 

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Discussion Starter · #9 ·
I run 9000 rpm, 1200 lbs open with .950" lift with a small diameter PAC dual spring.
Wow, what diameter spring is that? I have no intention of turning my motor more than 7500.
 

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Discussion Starter · #10 ·
I have T&D rocker stands also, but with Dart 355 cc heads, and triple springs.. I would not use the taller stands, unless you have taller valves than what the heads were manufactured for. The taller stand brings roller alignment with the valve problems. Same goes for lash caps, unless you have Ti valves. The little tool supplied with your set gets you your correct height. With a .040 and a .080 shim, you are raising the stand .120. There are .125 taller and .250 taller stands available. They swap out stands, as long as the engine has not been run. Your best bet is to call Sheldon @ T&D. Taller stands do not automatically mean longer stand bolts, as the taller stands are raised in the area above the bolt.
Make SURE you are using the absolute longest stand bolts your heads allow without bottoming out in head. With triple springs you want as much thread attachment as possible. They have many different length bolts available for this.
Advise you print their Parts page for reference as to what's available in bolts, but stand bolts must be flanged style.
I'd measure the retainer clearance with a wire gauge before you call Sheldon. Have exact information written down before you call.
Thanks. I’m starting to wonder if I need is some different locks to reduce the retainer height compared to the valve stem tip? That would then give me some additional clearance between the retainer and rocker. I haven’t checked to see what retainer locks I have.
The only problem that would cause is that the exhaust springs installed height might have to be slightly less (say, 2.05” vs 2.1”), although that might not even matter? I say that because I don’t have any shims under the exhaust springs, so I can’t drop them any deeper into the spring pockets.
Starting to think I don’t need these damn bigass springs, period, based on what you guys are telling me.
 

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Discussion Starter · #11 ·
Just checked the original build sheet from SRE. Those are indeed +.050 locks. Well spotted, Mr. Foxwell(y).
 
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Cam specs are 286/300 @ .050”, .836”/.816”. Pretty sure I need a triple spring for that.
To use lash caps I would have to change the locks (which isn’t a big issue) but I will most likely need a new set of stands from T&D, or at least some longer bolts, since I’m using a thin (.040”) and thick (.080”) shim under the intake stand as is.
With .836" on intake you can find several choices of dual, smaller dia. springs that will set up with less installed height. That will solve your problem. If you have a stack of shims under the springs, you should be able to get rid of them and the +.05 locks.
 

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Wow, what diameter spring is that? I have no intention of turning my motor more than 7500.
PAC has quite a few 1.50" duals with those specs. Certainly nothing you need.
If you go to a smaller dia. spring you'll need new retainers.
Do you have a spring p/n for what's on the heads? It would be good to find a more reasonable spring that fits your retainer. The PAC 1324 is a 1.625 spring that is good for .850" and will install @ 2.00". If you don't mind buying new retainers, you have lots of options in the 1.50-1.55 dia range.
 

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As stated, you should get an installed height down to bare head. You may be able to run a 0.030" spring locator, change locks to a standard height and give yourself an extra 0.050" clearance.

Now if you are in the mood to change everything up, I would look at the PAC-1373. Installed @ 2.050 will net 283lbs seat and 850lbs open. This is with a 1.430" OD dual spring.
 
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Discussion Starter · #15 ·
PAC has quite a few 1.50" duals with those specs. Certainly nothing you need.
If you go to a smaller dia. spring you'll need new retainers.
Do you have a spring p/n for what's on the heads? It would be good to find a more reasonable spring that fits your retainer. The PAC 1324 is a 1.625 spring that is good for .850" and will install @ 2.00". If you don't mind buying new retainers, you have lots of options in the 1.50-1.55 dia range.
The springs I have now are Comp #948: 1.645 diameter, 686 pounds per inch spring rate. They’re good for .910’ lift @ 2.1” installed height, so I’m thinking if I reduce the installed height to 2.05, by changing the locks to standard height, I should still be able to use the springs and retainers I have now and that should give me sufficient additional clearance between the retainer and the rocker, no?

What do you think the minimum clearance between the rocker body and the retainer should be?

I wouldn’t mind changing the springs, but these are brand new ones I just bought a few months ago, and I would need to change out retainers as well.
 

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I know you say your not gonna rev this eng over 7500 but things happen with power adders, you may also want to look at the installed height from coil bind to set these up, your coil bind is 1.130in + min gap for coil bind .055in + cam lift .836in = 2.02in installed height. New seat pressure would be 386 & open will be 950-960. Ex would be slightly different but alot closer .
Set up at 2.100 is way off on intake side .134 and ex would be .154 and a bit excessive to coil bind and you may get spring surge .055-.065 in from coil bind controls the valve more, you hiccup with nitrous from floatin valves or one sticking open your gonna hear a BOOM and see you hood move. Dropping your installed height may also fix your clearance issues on the retainer
 

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The springs I have now are Comp #948: 1.645 diameter, 686 pounds per inch spring rate. They’re good for .910’ lift @ 2.1” installed height, so I’m thinking if I reduce the installed height to 2.05, by changing the locks to standard height, I should still be able to use the springs and retainers I have now and that should give me sufficient additional clearance between the retainer and the rocker, no?

What do you think the minimum clearance between the rocker body and the retainer should be?

I wouldn’t mind changing the springs, but these are brand new ones I just bought a few months ago, and I would need to change out retainers as well.
Personally I don't think you need near that much spring pressure. I would take the inner spring out and see what you have at your minim installed height. You'll need a spring scale to do that. Don't rely on advertised coil bind. Put one of your springs in a vise with the retainer and squish it till it coil binds, then measure it. I agree with Saviour68 on how to go about it. Find your actual c/b, add .05" for clearance, then add your net lift (gross lift - lash) and that would be your minimum installed height. IMO if you have 280 seat and at least 800 open, you should be good to go. You should be running no less than a 7/16 x .165 pushrod. Straight wall on the ex, single taper on the intake. Minimum between the rocker...would like to see .06" but I think once you get this all sorted out you'll have plenty.
Don't take this the wrong way but running the wrong spring just because they're new isn't a very good reason. ;)
 

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Discussion Starter · #18 ·
I know you say your not gonna rev this eng over 7500 but things happen with power adders, you may also want to look at the installed height from coil bind to set these up, your coil bind is 1.130in + min gap for coil bind .055in + cam lift .836in = 2.02in installed height. New seat pressure would be 386 & open will be 950-960. Ex would be slightly different but alot closer .
Set up at 2.100 is way off on intake side .134 and ex would be .154 and a bit excessive to coil bind and you may get spring surge .055-.065 in from coil bind controls the valve more, you hiccup with nitrous from floatin valves or one sticking open your gonna hear a BOOM and see you hood move. Dropping your installed height may also fix your clearance issues on the retainer
Thanks,

I hear you on the over revving. I’m going to put a 7600-7700rpm chip in the limiter and shift it at 7200-7300 to make sure it doesn’t overrev, but I would like to stay off the limiter on nitrous for sure.
Are you saying that I can and should drop the installed height down from 2.1” with this spring, or that I should change out the springs?
I always ASSumed that the more clearance you had from coil bind the better? I learned something new tonight. Thanks for this.
I had no idea that I had way too much spring in this thing. I’m not a fan of using stiffer springs than necessary, and I know that a lot of people err on the stiffear side, which is just more stress on the valvetrain and robs a bit of power.
 

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Discussion Starter · #19 ·
Personally I don't think you need near that much spring pressure. I would take the inner spring out and see what you have at your minim installed height. You'll need a spring scale to do that. Don't rely on advertised coil bind. Put one of your springs in a vise with the retainer and squish it till it coil binds, then measure it. I agree with Saviour68 on how to go about it. Find your actual c/b, add .05" for clearance, then add your net lift (gross lift - lash) and that would be your minimum installed height. IMO if you have 280 seat and at least 800 open, you should be good to go. You should be running no less than a 7/16 x .165 pushrod. Straight wall on the ex, single taper on the intake. Minimum between the rocker...would like to see .06" but I think once you get this all sorted out you'll have plenty.
Don't take this the wrong way but running the wrong spring just because they're new isn't a very good reason. ;)
Thanks again for all the advice. It is greatly appreciated.
I don’t actually have a lot of faith in comp springs, although I previously ran a set of these 948s in my old 565 without any issues.
I was thinking I needed this stiff of a spring due to running stainless valves?
I don’t have a problem changing the springs out, and would much prefer to run the right spring, and from what I read, PAC and PSI makes better springs?
I’m certain I can get .06” clearance just by changing the locks to standard height, but now I’m thinking I need to change the springs and installed height to optimize coil bind as well?
Thanks for the advice on pushrods. Believe or not, my previous setup was running these springs with .080” wall 3/8 diameter pushrods. I was planning to run 7/16 .165“ wall tapered P/Rs on the exhaust and at least a .135” 3/8” dia on the intake. But it looks like I need less spring and more pushrod?
Thanks again for the advice.
 

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Wow, what diameter spring is that? I have no intention of turning my motor more than 7500.
They are 1.525" springs. I don't think you need a triple spring (I have never used one) and a smaller diameter spring would not only lighten your valvetrain up but it would give you ample clearance.

Lots of other guys in here giving advice, so I'll bow out. I'm a firm believer in there can be too many cooks in the kitchen. Good luck.
 
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