team39763

iTrader: (3)

I followed this procedure below and I came up with 1.5 turns.

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1. Using the EO/IC method, get the lifter to the base circle of the cam.
2. Using a known length pushrod (7.400" is a good start with stock rockers) run the rocker arm bolt down to zero lash. This is easily done with your fingers "wiggling" the rocker, the point at which the "slack" is just gone is zero lash.
3. Set your torque wrench to 22 lb./ft. Tighten the rocker to full torque and count the number of turns it takes to get there. 1 full turn wtih a stock 8mm X 1.25 bolt is ~.047" preload as measured at the pushrod/rocker interface.
4. I normally shoot for 1 1/4 to 1 3/4 turns with stock type lifters like Comp 850's, LS1, LS7 etc.

For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter...

I might not know everything but I will tell you that this method has worked for me year after year cam swap after cam swap. We average 3 cam swaps a week here so you can do the math.

If you are not familiar with the EO/IC method for determining valve events in a 4 stroke engine, its very simple:
For a given cylinder as the Exhaust valve is Opening, the intake lifter will be on the base circle of the cam and lash/preload should be checked for that intake valve.
For a given cylinder as the Intake valve is Closing, the exhaust lifter will be on the base circle of the cam and lash/preload should be checked for that exhaust valve.

THIS METHOD ALWAYS WORKS!!!
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The guy that had the heads done told me they were warped pretty bad and they were milled ten thousandths because of this. .0010(other guy expressed it like this) doesn't seem like it would fix a warped head, so could he mean .0100? In that case wouldn't the stock 7.4" pushrod be too long? When I tried the above method, it checked out fine. I don't have a pushrod length checker yet, but I'm hoping to get one soon.

01ssreda4

iTrader: (96)

If you got 1.5 turns you are good. I personally have used that method several times and it turned out perfect each time.

vettenuts

iTrader: (4)

Since pushrods (unless you get custom) are only available in length increments of 0.025", you would have to mill more than 0.010" to affect the pushrod length much.

team39763

iTrader: (3)

Ok thanks guys. I think I was confusing myself with the tens, hundredths, thousandths thing. I'll go buy some good 7.4" ones now.

vettenuts

iTrader: (4)

Are you using the stockers for this measurement? Note they are not 7.400", they are 7.385".

team39763

iTrader: (3)

Yes.

I don't know why i thought 7.4 was stock, must have misread something. I'll see if I can find that size. I'm using a aftermarket cam if that makes a difference, but it sounds like I need the stock length pushrods. Thanks.

Edit: Why do most cam kits come with 7.4 pushrods? The last three cam kits I installed came with 7.4 pushrods - one with slightly milled heads and two with stock heads.