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Re: [Re: Race Prep]

To: WSpohn4@aol.com, mgs@autox.team.net
Subject: Re: [Re: Race Prep]
From: Matthew Trebelhorn <matttrebelhorn@netscape.net>
Date: 3 Aug 00 12:57:43 EDT
WSpohn4@aol.com wrote:
>With a stock cam you can use stock springs. I'm at work and don't have all my

> material here, but I believe the stock valve bounce is about 6200 rpm or so.

> The power peak on a stock engine is well below 6000, but you can run it to 
> 6000 all day without needing a cross-drilled crank. 6500 is the frontier 
> beyond which stock cranks should not venture!
> 
> If you are using a stock gearbox, you will _need_ to use 6000, so that you 
> hit somewhere near the torque peak in the next gear. 
> 
> Bill S.
> 
> PS - have fun!


I'm a bit slow following up on this, but I've got some questions.

First, what is "cross-drilling" the crank?  How does that help?  I assume that
this is a "find a good race prep shop" type thing, and not an off-the-shelf
item, yes?  What are the methods and reasons for strenghtening a crank?

Second, about the stock crank:  I have a slightly warmed-up cam, stiffer valve
springs, etc.  In my last autocross, I touched 6500 at the end of one
particular straight, on each of five runs.  

Once, a couple of years ago, the throttle stuck on a shift, and went from 6000
to well past 7000 in the blink of an eye, burying the needle on the tach.  I
shut it down ASAP, but still a bit worrysome.  

So, I'd say that my motor has spent maybe 15 seconds of its life at 6500+ RPM,
with maybe 5 of those at over 7000.  Is the crank just going to snap one of
these days, from the repeated abuse?  (Oh, it's a 5-main, from 1970, and it's
ground .020) 

Just trying to learn more about the bottom end -- any info. appreciated.

Thanks,
Matt

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