05 LS2
OEM lifters
OEM heads
TSP dual valve springs
TSP 228/232 112 LSA
I’m using pushrod length check tool. On base circle intake I get 11.5 turns ZERO lash hand tight.
11.5 x .050 = .575 + 6.80 = 7.375
So now I add .070 for OEM lifter preload giving me a total pushrod length of 7.445??
If yes do I use a 7.450 pushrod which will give me .075 preload?
thanks

 

You don't need to be concerned with those 11.5 turns of the bolt.

1. With the stock 7.40" pushrod installed along with your OEM valve lifters, turn the engine so the lifter your checking is on the base circle of the cam

2. Then turn down the bolt until you get resistance on the bolt (that's zero lifter preload)

3. Then count the turns of the bolt until it's to the torque spec of 22 Lb/Ft.

You have the correct length pushrod and the correct lifter preload if it takes between 1 and 1 1/2 turns of the rocker bolt.

Recommended lifter preload is between .070" and .130" (If it takes 1 1/4 turns of the bolt, you will have approx .110" preload on the lifter)
____________________________

If the preload your checking is ok, no real need to check all of them ... they will be the same as long as all the pushrods are the same length.

BTW ... Aftermarket cams for these engines have just a very slightly smaller base circle than the OEM cam has, but in most cases, the OEM 7.40" long pushrod will still give you the correct preload with your aftermarket cam.

 

Ok did exactly what you stated to do.
My TSP 7.4 pushrod on base circle.
zero lash finger tight rocker
when torquing to 22 lbs I went 1/2 turn then started to do another 1/2 for torque wrench clearance. Only got about 1/8 more turn before hit 22 lbs.
so I’m hitting 22 lbs before I even get close to 3/4 of a turn.
I’m so confused.

 

That would indicate you need a shorter pushrod (if) your lifter was in fact on the base circle of the cam lobe.

But, if anything, these aftermarket cams in most all cases have a slightly smaller base circle than the OEM cam, so if anything, they would need a longer pushrod.

I am confused ..... I am thinking that your lifter was not exactly on the base circle of the cam lobe when you checked it. There is no way in hell that your aftermarket cam has a larger base circle than the OEM cam.

Again, the stock 7.40" pushrods should be perfect for your LS2 with that cam you now have ....... Are you sure your rocker arms and lifters are OEM in that engine?

.

 

A 7.45" pushrod is way too long for your LS2 (that's 50 thousands of an inch too long).

Again, you should be using 7.40" rods

 

Lifter on base circle and using a stock 7.40" pushrod ... check how many turns it takes from zero preload to 22 Lb/Ft torque

 

all stock rockers. All I did recently is a CHE trunnion upgrade.
I’m the second owner and as far as I can tell all is OEM.
I’m on base circle. I did the EOIC method.
Turned crank over until exhaust pushrod came up slightly then checked off the intake side.
Checked both # 1 and 2 cylinders with same results using checking tool or method you described.
also used TDC method same outcome.

 

I will try “stock” pushrod tomorrow. It’s actually 7.385 length.
I still not getting why the pushrod measuring tool isn’t accurate. Or am I missing something?

 

Sorry, but I'm lost here

All I can tell you is that if you have the stock length valves, stock rocker arms, stock lifters and the heads have not been milled down too much; . with that cam, you need to use a 7.40" pushrod.

That's the best I can provide ...

 

That's a fact, the OEM pushrod may be advertised as 7.40", but it's actually just slightly less (7.385" seems about right)

 

Ok I just tried It with “Stock” pushrod. Only got barely 1/2 turn to 22 lbs from zero lash.

 

Sorry ..... I am clueless at this point

I would get on the phone and talk to one of the big engine builders on this forum ... I am sure they would give you a couple of minutes of there time.

Good luck with all this

 

Just for the hell of it ..... Install the stock pushrods and put the piston on TDC (all the way to the top) on the compression stroke and check it then ... should only take you a couple of minutes to do.

 

Thank you for your time.
Hopefully someone else can chime in to what is going on.

 

For whatever reason, you need a longer push rod that will increase preload. You're really close in your initial post. I turn the engine over until one valve is wide open and do the measuring on the other valve on that cylinder. I know that's not the "approved method of finding the base circle on the cam, but it works for me and is easy to do. Measure the adjustable length push rod after you get it to 0 lash. Add .1" and you're there. I've never seen any appreciable differences between valves, but it's easy to check a few once you get what you think is 0 lash on the push rod checker. I check all four corners and call it good. Again, the purists will say check them all and you may need a different size pushrod on every lifter. On a stock long block, that's a total waste of time.

 

were did you come up with .130? TICK likes to go .100 on OEM lifters and that's considered tight. To the OP I think you had it right the first time, this **** will drive you mad!. pick one as you have a lot of room for error, I've got like five "used" sets if you want to experiment

 

ahp ...

 

In order to set preload correctly this way, you have to make SURE that you find zero lash, otherwise it’s a waste of time.
If you’re looking for resistance to tightening the rocker bolt, you’re doing it wrong, because the plunger in the lifter will depress significantly before you feel any resistance to turning the bolt, so you won’t actually be starting from zero lash, which may be the problem. What you need to do is start with the rocker loose, lifter on base circle, then carefully and lightly hold the pushrod (without touching the rocker) between your index and thumb and rotate it back and forth while slowly tighten the bolt with your fingers, without putting any pressure on the rocker body. Tighten carefully until you feel slight resistance to rotating the pushrod. Stop there. That’s zero lash. Then pay close attention to the amount of rotation from there to where the torque wrench clicks at 22 ft. lbs. Most folks say anywhere between 1-2 turns is fine for the stock lifters. The stock lifters have a lot of tolerance built into them.
Also, bear in mind that with hydraulic lifters, too much preload will tend to cause lifter pump-up/valve float earlier in the rpm range, so it’s actually best to run as little preload as possible (shorter pushrod). The real risk with running too short a pushrod is that if it’s not long enough to keep the plunger from hitting the retaining clip, the lifter could come apart a high RPM, especially with stock lifters that are held together with a wire retainer, rather than a proper cir-clip.
I’ve run stock LS lifters at ~3/4 - 1 turn before myself, with no issues.
To be safe I would aim to get the recommended ~1 - 1 1/2 turns on the bolt from zero preload and call it a day. But if it ends up being only very slightly short of 1 turn, I wouldn’t lose any sleep over it.
As mentioned before, if you’re working with a stock deck height, stock gaskets and stock, unshaved heads, then a 7.4” pushrod will work 99% of the time.

 

Thanks CI GS I will try tonight and confirm results...

 

OP ....

Do what you want, but if everything in your valvetrain is stock and your heads have not been shaved ... just install a set of aftermarket hardened 7.40" pushrods and forget all the rest of this stuff.

Like I said before, these mild aftermarket cams have a base circle just 'slightly' smaller than your OEM cam (slightly, meaning the aftermarket 7.40" pushrods will be fine).