Valve spring bounce

StanTheMan · Postby **StanTheMan** » Sat Jun 24, 2017 11:44 am

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.....

Todd77 · Postby **Todd77** » Sat Jun 24, 2017 6:04 pm

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.

StanTheMan · Postby **StanTheMan** » Sat Jun 24, 2017 7:09 pm

Ok. No misfires.

I'll check the filter.
Cheers

manga_blue · Postby **manga_blue** » Sat Jun 24, 2017 9:04 pm

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.

madjak · Postby **madjak** » Sun Jun 25, 2017 2:22 pm

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.

StanTheMan · Postby **StanTheMan** » Sun Jun 25, 2017 6:55 pm

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.

SnaveSnavely · Postby **SnaveSnavely** » Sun Jun 25, 2017 8:31 pm

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...

Todd77 · Postby **Todd77** » Sun Jun 25, 2017 8:58 pm

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.