Thread: Adjustable push rods / roller rockers on 4.6 V8?

Usually it is part of a head service to level the valves.
Regards Philip A

I went through this recently.

I bought steel rockers from Turner Engineering in the UK as replacements. One of the pads came off my old alloy rockers at high revs. The aluminium then disintegrated, sending metal through the motor.

I also bought adjustable pushrods from Smith Brothers in the US. I called them and ordered direct. It cost nowhere near as much as other sites advertise. I did have to drill out the pushrod holes in the heads to a slightly bigger size though. Smith Bros make the push rods to your own length specs, so from memory, I chose the length so that the midway of adjustment was equal to the standard pushrods length.

Result is that the steel rockers are working perfectly, and all lifters have the same preload, resulting in no ticking from my motor. Very happy.

Regards
Andre

I've got a set of new alloy rockers that came with a new engine, but I got a set of steel ones from Turner to use instead. Highly recommended.

Are your wonky valves all seated by the same amount?

Looks like I'll have to remove the heads (damnation!) to widen the holes if I fit the pushrods...

thanks Philip A. I'll call the machine shop tomorrow - I don't know how much they skimmed the heads by -they assured me it was less than 0.5mm...

I used new composite (Elring) head gaskets - that's as far as I got before I had to "cease and desist"! for 4 weeks. I torqued them down with ARP studs so they should be OK. I'll get new gaskets.

Thanks Davo, I'll contact Turners.

I like the idea of the adjustable pushrods so will contact Smith Bros...
Andre, can you remember what diameter you widened the pushrod holes to ?

thanks again...most appreciated..will report back!

Unfortunately I can't remember the size drill bit I used. I found it mentioned on a forum and just used the recommended size from there.

Just a bit of advice on setting the preload if you get adjustable pushrods. Use a feeler gauge between rocker and valve stem as you lengthen the pushrods to feel for drag when the slack is taken up. This will give you an accurate start point for preload. To set preload, I simply measured the chosen distance on the threads, and counted how many flats the the top section had to be screwed out by after the slack was taken up. Then lock with the lock nut. I also bought a couple of 3/8 spanners to make the job easier.

Cheers
Andre

FWIW: Just an update on "steel" rockers. I'm not sure whether they're steel or cast iron. However, the lass at Turners who took the order told me that the ones they sell are a matched set ...they buy a lot of them and then measure them up into sets for their own production engines as well as sales. If so, the extra few $$ seems worth it to gain some semblance of Quality Control.... she also mentioned that "most of today's orders seem to be headed to Australia!"

The steel rockers (plus 3 sets of shims) arrived from Turner Eng. and got them fitted last week.

There are three issues: The heads had been machined (for the first time) and I used composite (Elring) head gaskets. The originals were steel! Further, running a straight edge across the tops of the valve stems, there was a significant discrepancy as mentioned in another post (20thou...)

I don't know how much they took off the heads (I suspect close to 0.5mm which approximates to 20 thou. No doubt this is offset by the thickerhead gasket.

Measuring the preload with various bits of bent wire was a disaster. There had to be an easier way...there is:

I have a $40 digital vernier caliper which I calibrated for consistency and accuracy. It is as precise as a friend's $200 version! It has a "step" measuring function: when the jaws are separated, a thin rail appears from the other end, allowing one to use it as a depth gauge.

I took a couple of new lifters and measured the depth of the face of the piston below the top edge of the lifter several times on each lifter : average was 109 thou +/- 0.5 tho. This is then the zero position of the lifter at "rest".

I was then able to measure the preload of all 16 lifters at TDC by resting the base of the caliper across the top of the lifter and opening the jaws until the rail touched the top face of the lifter piston.

For consistency, the calipers stood upright but parallel to the face of the inlet ports which meant they sat 'flat' on the top edge of the lifter. I was surprised to find that on the RH bank the values varied between 71 and 103 thou while on the LH bank, the corresponding values were between 74 and 101 thou. I then rotated the crank again and remeasured. The second lot of readings confirmed the originals.

Modelling the results in a spread sheet and using a ratio of 1.55 discovered that using the 31.5 thou shim set gave best results for both heads.

Preload values for the RH bank: 4 were grouped in the mid-20s and the other four between 45 and 50. For the LH bank 5 were in the mid 40s, the others 25,34 and 52 thou.

Fitted shims and remeasured...all within 1-2 thou of the calculated numbers.