Working on a 2009 rebadged Holden Caprice with an L76 AFM engine.

The car had a few issues from the previous owner and had to tear half of the engine down to replace a whipped out Camshaft, lifters, timing chain tensioner, couple of bent pushrods, AFM valley cover. The cover was packed with silicone and clogged the oil passage.

So far got new parts that includes

Camshaft 12625438

AFM lifters 12645725

Regular lifters 17122490

New Cam gear

New timing chain

New chain tensioner

New AFM valley cover (VLOM)

Mahel gasket set and all the other necessary parts

Milled the cylinder heads 0.004" for cleaning

...........


Now to my understanding the OEM pushrods should be 7.325" in length for this particular engine but notice the pushrods that I've removed measured at 7.400" (my guess previous owner swapped them).

So i decided to get a pushrod length checker and measure the actual needed length. So i began to log the results for zero lash without adding any preload and saw different numbers through all of the valves, now i understand rocker arms along with valves get worn up after miles of use and whatnot.

But! The numbers seem a bit strange between AFM cylinders and none AFM cylinders...

AFM cylinders result no preload added (zero lash)

7.315"
7.304"

7.310"
7.327"

7.307"
7.304"

7.312"
7.304"

__________

None AFM cylinders result no preload added (zero lash)

7.265"
7.262"

7.267"
7.264"

7.261"
7.259"

7.258"
7.258"

__________

The AFM require longer pushrods than the regular cylinders as noticed for some reason. I did some math and couldn't come up with a single number that can work for all cylinders. I know i could get different pushrod length to each cylinder, but is this normal for that big of a difference between the AFM and none AFM valves?

I came up with 7.395" for the AFM after averaging the difference between the highest and the lowest number. And came with 7.342" for the regular ones (0.080" preload included).

I've tried averaging between all and the only number i come up with is 7.369" if that makes sense.... But i know with this number I'd be over or below the tolerance on some valves preload.

To my understanding 0.080" is needed by the repair manual, 0.060" is minimum and 0.100 is maximum from what I've gathered searching around. Any ideas or advice would be appreciated.

 

Stick a stock pushrod back in there, run the bolt down to zero lash, then count the turns to get the bolt tight and see what you get.

 

The stock pushrods according to the parts catalog should be 7.325"

the ones that were fitted when i remov the rockers are 7.400" and I don't have the originals in hand. All the measurements above are at zero lash and rocker arms bolted down to 22ft lb.

Is it okay to test your way with a pushrod length checker set at 7.325" or should i try it with the 7.400"?