hazard2k

iTrader: (10)

Currently I have a TR224 cam installed with texas-speed 7.400 pushrods on the stock heads. I am about to be putting some patriot LS6 heads that have been shaved down .030

My question is if I will need new pushrods with this setup or will the 7.400 be fine? I am not sure if the TR224 has a smalled base circle than the stock cam. If it does, I guess I have been running a tad bit longer pushrod than needed for a year.

I was debating getting a pushrod length checker, but I don’t know the proper way to check it once I get the tool. Any help here would be great too.

Thanks, Jeff

ss.slp.ls1

iTrader: (36)

Get the adjustable pushrod. Going purely off memory, should be something along these lines: Mark the top of the valve stem with a marker. Adust the pushrod go a certain length, tighten down the rocker, and when the lifter is on the base circle (valve closed) wiggle the rocker. Loosen and remove the rocker and you should see a line across the valve stem where the rocker came in contact with the valve stem. The line should be 1/3 the way in from the intake side.

vettenuts

iTrader: (4)

Here is how to measure noting pushrod length has no bearing on wipe pattern or where the rocker contacts the valve stem.
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Each turn of the pushrod is 0.050". When fully closed, it is 6.800". This is pushrod "gauge length" so you can't measure it directly as the pushrod length is actually based on the length between the ball ends where the ball end measures 0.140" in diameter. Assuming you are using stock rockers or a non-adjustable rocker.

1. Open the adjustable pushrod to the same length as your stock pushrods
2. Close it down two turns
3. Put your rocker rail on the head
4. Make sure you cylinder (typically #1) is at top dead center on the firing stroke so both valves would be closed
5. Put the pushrod in place on the intake valve and make sure it is in the lifter cup
6. Install the rocker and snug down the bolt (don't need to torque, just make sure it is snug)
7. Lift rocker tip up and down, if it "ticks" the pushrod is too short. If you can't easily move the rocker the pushrod is too long.
8. You can try and adjust the pushrod in place buy my fingers are too fat so I end up pulling the rocker and adjusting the pushrod length. Go either shorter or longer 1/2 turn and try again.
9. You are trying to get to the point where the lifter doesn't "tick tick" with the pushrod in place nor is the rocker snug. When you get the pushrod length such that you just barely get rid of the "tick tick", you have found "zero lash".
10. When you have found zero lash, carefully remove the rocker and pushrod without rotating the pushrod.
11. Tighten the pushrod until it is fully closed counting the turns as you go.

To figure out your pushrod length you do the following. Lets assume it took 10-1/2 turns to close the pushrod down to its shortest length after you reached zero lash. Each turn is 0.050".

Your length is then: 6.800" (fully closed length) + 10.5 X 0.050" (number of turns times the length change per turn) = pushrod length minus preload. So for this case:

6.800 +10.5 X 0.050 = 7.325"

This is the length you measured to zero lash without any lifter preload. Now lets say you want to have 0.075" lifter preload, you add that to the measured number and you end up with 7.400" pushrods.

Now repeat for the exhaust valve to verify the length. If you have something like Yella Terra's, it is the same procedure but you must snug down the rocker pair rather than the single rocker.

ss.slp.ls1

iTrader: (36)

Good to know.

What affects the wipe pattern then, I read it somewhere.

vettenuts

iTrader: (4)

With any fixed rocker (non-adjustable) the wipe pattern can be changed by moving the pivot point of the rocker, typically shims to raise the pivot point. However, sometimes you encounter the situation where the rocker is too high (wipe it too close to exhaust side of valve). Then you either need to do machine work or use lash caps to alter the valve stem height and move the wipe pattern back towards the intake side of the valve stem.

Since he knows his milling, he can likely go with 7.375" pushrods since the head will lower by 0.030" but it is always best to measure after setting geometry (wipe).

hazard2k

iTrader: (10)

awesome info guys thanks!

Does anyone know the base circle on a stock cam? Its a tad bit larger than that of a TR224 correct?

vettenuts

iTrader: (4)

I don't have exact numbers, I seem recall that the differences between stock and aftermarket are generally about 0.025" radius but best to check or find the real numbers as I may be wrong.

farmdawg

Sorry for the hijack here, but:

I followed your steps listed earlier in this thread, and at 7.4 pushrod length, I could turn the pushrod fairly easily with my fingertips, so I started there and increased by .025 until I could no longer get the ticking sound by pushing on the rocker arm and listening. On the intake it went 1.5 more turns to an equivalent of 7.475 and on the exhaust side it went 2 turns to an equivalent of 7.5. This left the plunger solid and no more flex or tick sound when pressed on. So I counted the turns back in and intake was 13.5 to closed and exhaust was 14 to closed. So using your method, I would add my preload to those numbers then, correct? Meaning if I wanted to use .080" preload then intake would need 7.555, and exhaust would need 7.580 length pushrods, is that correct, or should I just use pushrods long enough to keep the lifter solid feeling and not flexing when I push down on the rocker arms?

That seems a little on the long side to me, my cam specs are 226/234, .598/.599 and a 117 lsa. I think my car is a freak, someone esle had the same setup I'm running and with 7.4 pushrods ran fine, mine ran ok, but was hella noisy in the valvetrain, and would get louder as the engine warmed up. The rest of my mods are in my sig and I just put new lifters in, but with the old ones I got the same figures, I thought that I had too much bleed off so I changed the lifters out and put some new ones in.