3.2 Carrera valve float
 

With a stock 3.2 Carrera, at what RPM do the valves float?
Thanks, Donn

About 8,000 rpm but it can begin to happen as early as 7,200 rpm...

But there is no benefit in exceeding the red line in your stock 3.2

8,200 rpm is on the extreme limits of your engine.

Hope you have good rod bolts.

Good point... I was thinking about valve float only.

Thanks for the input. I wasnt planning on running over 7000 on purpose. The error occurs when you miss a shift. Usally downshifting too soon under braking or accidently selecting 2nd when you were going for 4th. I have done this before with another engine and broken rocker arms.
I am putting together a 3.2 race engine for the Spec 911 class and just was figuring how much margin I would have. I am planning on running some aftermarket springs. I know what the stock spring pressures are and what the new ones will be. I was hoping to extrapolate to what the new limits will be.

Thanks again, Donn

Donn

Shortly after I installed some race springs I missed a shift and saw 10,500 rpm on the memory tach. Thought my weekend was done, but not so - no broken rockers, and a quick leakdown showed nothing amiss. Elgin 315 cam, decent lift, lots of overlap.

I had Racewear rod bolts on stock rods in a 2.7 race motor. The 3.2 probably has more reciprocating mass, and heavier valve train if mostly stock.

This may have shortened the lives of the springs, as some time later I had a spate of broken inner springs (valve float around 7,600 - felt like a soft rev limiter).

Then, again, the next set of springs started breaking outers.

Doesn't sound like something worth worrying about if your most efficient shift point isn't above 7,000 rpm. If you miss a shift, it is a crap shoot whether you have damaged something.

Walt

Here's a link to my thread that may be relevant... http://forums.pelicanparts.com/911-engine-rebuilding-forum/515242-rpm-limit-3-4-w-arp-bolts.html