Sure does sound like a nice little engine.

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Obviously you will have to replace all worn bits and pieces but I would also take a close look at the rocker shafts for "out of round" where they are mounted on the posts. This can be caused by overtightening or softening of the material in the posts. I believe this can lead to the clearances between the OD of the rocker shaft and the ID of the bore in the rocker arm changing. Over time and with big revs and high rotational loads the "out of round" clearances can lead to lack of oil pressure at the rocker bore and some binding takes place. Obviously a slightly sticky rocker is the outcome and this can be hard to notice if your engine only does it at high revs. When left unnoticed this led to the failure in the engine I mentioned in the earlier post.
The T6061 spacers basically replace the springs between the rocker arms. In the standard spring set up you can watch the oil pumping out of the side of the rocker, the High tensile spacers dramatically reduce this spillage. If made to the right clearances they mean that the rocker bore sees better lubrication.
I kinda wish my coupe engine was apart and I could take a pic of the spacers.
If you decide to make some up, measure carfully because not only do you need to consider the diameters but also the end floats, both individually and collectively. When fitting to your engine you will have to measure each end float with feeler gauges and set up individually so you have the right clearances for good lubrication.
Was good cheap effective fix, just took a little while to set up but meant no more severe wear rates at the rocker assembly or the pushrods, cam and lifters.
I would also like to know the pushrod material you use.

The push rods are of lightweight material from Tomei. The push rods are not damaged.

At the risk of sounding totally stupid. Is it that the lack of oil flow from the rocker shaft/ rockers and down through the return ports over the cam and lifters wiped them out .

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Oil is pumped up one post and into a hollow rocker shaft then out through holes to feed the rockers etc.

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I am not saying that, just telling you about things I have noticed and hence improved on a highly strung A series. Your problem could very well be as feral suggests because he knows his stuff and his point is worth noting.
I had cam and lifter wear rates above the norm and as I said "it took a while to figure out". Basically had to measure and carefully inspect all contact surfaces for signs of wear or "out of round". The extra clearance at the rocker to valve stem due to a sticky rocker can lead to "hammering" of the lifter faces and cause excessive wear in lots of places because the materials eventually breakdown and in the worst cases fail.

You guys are the best . I will keep you updated throughout the repair process.

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There should be so much oil mist flying around in the crankcase, from the big ends & main bearings, that oil flowing down from the top would not be needed to lubricate the cam.

Yikes, the lifter face is completely gone on some of them.

Quote:This picture shows a standard lifter compared to an aftermarket lifter that has a larger radius lifter face. It's only a mm or two, but apparently makes a big difference:


Lifter comparison


Quote:Here's the picture:

Rocker arm spacers

Thanks dd,
Now members can see what I am talking about. Cheap effective modification for high rpm applications.
It should be noted that some extra weight can be removed from the spacers pictured. Obviously you need the OD to be the same as pictured (where they meet the rocker end faces etc) but you can machine off some of the excess material along the middle section of the OD to reduce the wieght.

one thing to note, the NISMO lifters for the A series engines are hollow, and the convex head will collapse if not treated properly.
If you're using 10k rpm you must be using them, the stock ones are just too heavy for these rpm.
You really need good oil and a proper warmup routine, and you replace them every 2 seasons. (around 1000k's)
The most I ever got was 5 seasons out of a set, and I wasn't doing anything like those rpm...