VerdeZ28

So I am finishing up my 02 z06 head and cam swap. I have the heads on and I measured the pushrod length using a pushrod checker tool by comp cams. thing is that I am getting two different measurements for intake and exhaust. I made sure that both intake and exhaust were on base circle. I got 9.5 turns for intake and 9 turns for exhaust to get to zero lash. I think this may be because my intake is LS3 turned down and the exhaust are ferrea stainless and the valve heights may be different. The lifters I am using are LS7 lifters.

If i average out the turns to 9.25 I basically have to choose between a 7.350 or a 7.325 length pushrods depending on the preload.

If I go with 7.350 the intake side will be preloaded .075" and exhaust will have .100 preload

if I go with 7.325" the intake side will have .050" preload and the exhaust will have .075" preload.

Which of these setups would be best? has anyone running a similar setup seen this phenomenon? the cam is 228/230 .571/.573 on 112 LSA and 110 ICL btw and the springs are PSI 1511ML. The lifters are LS7 lifters btw.

ckpitt55

iTrader: (4)

getting different lengths is normal. all 8 pairs of mine had between .020-.030" difference on average (exhaust were shorter).

if I'm reading this correctly your 9.5 and 9 turn measurements were at zero lash, correct? to get the appropriate length with preload, you'd have to add whatever you want on top of your zero lash measurement.

closed length + (#turns * .050) + desired preload = final length

What is best depends on what lifters you're using.

JakeFusion

iTrader: (7)

It's not uncommon. It's probably less the valves (I have LS3 intake and Ferrea exhaust and don't recall there being a difference), and more the cam lobes may be different intake to exhaust.

I'd order what you need for ideal preload. Go to Manton or Trend and get custom pushrods.

baronsmith98

iTrader: (2)

Just ran into this myself a few weeks ago. I was able to run .075" and .093" on mine using 7.350 length pushrods. I was aiming for .080" so I feel I will be ok.

VerdeZ28

Thanks for the response guys. So now that I feel ok with getting different measurements, what preload should I shoot for with the LS7 lifters? I am looking to achieve best valvetrain stability possible.

JakeFusion

iTrader: (7)

.060-.080" preload with LS7s.

poltergeist 02

iTrader: (65)

I had the same issue last year using Manley valves. I ended up using two different size pushrods to get the preload correct and the funny thing is I was running the same cam that you are now. If you are interested, I changed my whole setup and I have no use for the pushrods anymore. I have 8- 7.325, 8- 7.350, and 8- 7.375 I will let them go cheap. I don't even think they have 500 miles on them.

VerdeZ28

I double checked it making sure the the timing was right so that I would be on the base circle of the cam and I came up with 9.25 turns for both intake and exhaust.

For what's readily available I can go with .063" preload or .088". Which should I go with?

poltergeist 02

iTrader: (65)

The .088" will be quieter. I tried .057" and it sounded like a sewing machine, I upped it to .082" and it was much quieter with the LS7 lifters.

VerdeZ28

I went with the 7.350" pushrod. that should put me at .088" preload.