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So I know what it is.
Never experienced it to my knowledge.

How do you tell?
Is there lots of noise?
Sudden unexpected loss in power at high rpm.

I have aggressive cams with the standard 58lbs springs. They would be the originals.
I have a new set lined up. 66Lbs
I max out at 7200 B6 motor
But currently it power disappears at 6500 rpm. It used to go all the way to redline.
Can't hear any unusual noise.....

If you are getting valve float due to lack of valve seat pressure, it will come thru like a misfire up high. As for power dropping off lower than normal, check your fuel filter isn't partially blocked.

Ok. No misfires.

I'll check the filter.
Cheers

Valve springs in mine died at around 170,000kms. Standard springs, valves and cams. 31 out of 32 springs failed to meet Mazda's tolerances in a spring compression test. Power fell off progressively from 6,500. No other symptoms. Swapping to Supertech duals (eventually) restored power to linear up to 7,600 red line but I went through a lot of drama before that with aftermarket "performance" springs that broke.

I was floating my valves at 8500rpm but only just. They got hammered into the head and eventually the engine was having issues starting due to compression losses. I still had full power at revs though and even set my pbs just before rebuild.

New valves, guides and remachined seats were required.

Thank you chaps,
Ive been back on 98 for about 4 weeks. Changed the filter twice while on E85. Ive got another one on the way.

Interesting stories madjack & manga- blue. I don't have plans to rev the crap out of Patchy. It will be interesting when the new valves get installed . how she runs.

I definetaly don't have broken valves at this moment. I don't have any backfires at 7000 rpm either.

perhaps worn out valves....don't spring pressure measuring tool. Id rather spend that money on other stuff.

manga_blue wrote:Valve springs in mine died at around 170,000kms. Standard springs, valves and cams. 31 out of 32 springs failed to meet Mazda's tolerances in a spring compression test. Power fell off progressively from 6,500. No other symptoms. Swapping to Supertech duals (eventually) restored power to linear up to 7,600 red line but I went through a lot of drama before that with aftermarket "performance" springs that broke.

Very interesting...

StanTheMan wrote:Thank you chaps,
Ive been back on 98 for about 4 weeks. Changed the filter twice while on E85. Ive got another one on the way.

My car is on e85 and I tend to change filters after every 5 race meetings. I run a pre surge tank filter and a pre rail filter. When I pull them out after 5 races I would say they are 50 percent blocked. The e85 must do something to the filter, because I drain my tank and it is crystal clear.