Drilling Crank Throw Journals: How Much? - Team Camaro Tech
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post #1 of 9 (permalink) Old Jul 27th, 09, 09:33 AM Thread Starter
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Joe
 
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Drilling Crank Throw Journals: How Much?

I'm building a small journal 327, .030" over, which should make about 425 net HP @ 6500 RPM.
The crank throws are ground/polished to .020 undersize, which now makes them 1.980" OD. How much can I drill out the throws?

Thanks in advance.

Joe
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post #2 of 9 (permalink) Old Jul 27th, 09, 10:04 AM
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Re: Drilling Crank Throw Journals: How Much?

What kind of drilling did you have in mind?

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post #3 of 9 (permalink) Old Jul 27th, 09, 11:50 AM
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Re: Drilling Crank Throw Journals: How Much?

Talking about cross-drilling?
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post #4 of 9 (permalink) Old Jul 27th, 09, 12:07 PM
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Re: Drilling Crank Throw Journals: How Much?

This can be done but expensive, rebalance, re-champher oil holes etc, I would look into getting an aftermarket crank from Eagle/Scat/Callies, etc. and keep the 327 crank aside if its forged. Just my 2˘

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post #5 of 9 (permalink) Old Jul 27th, 09, 05:33 PM Thread Starter
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Joe
 
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Re: Drilling Crank Throw Journals: How Much?

It is an original forged crank from a SHP 327/365 horse engine (L76).
I want to lighten the throw journals, same as Scat/Eagle/Calles does, in order to cut recip weight. I have also installed ultralight wrist pins in order to further cut recip weight. The goal is to enable me to remove max amount from the counterweights via diameter reduction/knife edging. Aim to minimize windage and inertial weight of the crank.

I am not talking about cross drilling.

I am committed to keeping the engine with a short, 3.25" stroke, and so aftermarket cranks are out of the question. Furthermore, this assembly will be installed into a specially prepared small journal 870 block.
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post #6 of 9 (permalink) Old Jul 27th, 09, 05:55 PM
 
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Re: Drilling Crank Throw Journals: How Much?

What type of car or boat are you using this in. Are you racing with it.
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post #7 of 9 (permalink) Old Jul 27th, 09, 06:10 PM Thread Starter
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Re: Drilling Crank Throw Journals: How Much?

Quote:
Originally Posted by Rogers Performance View Post
What type of car or boat are you using this in. Are you racing with it.
Mike,

Engine is going into a '65 Corvette.
It will be for street/strip use.
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post #8 of 9 (permalink) Old Jul 27th, 09, 06:21 PM
 
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Re: Drilling Crank Throw Journals: How Much?

Joe,

The engine won't know what kinda crank is in it so I figure that you will be MONEY ahead to buy an aftermarket crank that you want!

You have already went way beyond a stock rotating assembly when you have talked about lightening everything up, so why worry about the crank now??

pdq67



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post #9 of 9 (permalink) Old Jul 27th, 09, 06:48 PM
 
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Re: Drilling Crank Throw Journals: How Much?

Don,t make it any lighter then it is. The car will need some crank weight to keep the engine spinning between shifts. If you make it to light the car will decelerate to much and to fast. Once you wind the engine up you need to keep the energy stored in the rotating assemble if you make it to light it will drop in RPM to fast.

I build a lot of circle track two barrel engines and some times i have guys complain that they can,t drive the car.
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