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Regrinding The Crank On A Race Engine?


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#1 grizzler73

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Posted 20 March 2018 - 10:35 AM

Hi Everyone

I have a std/std CAM 6232 crank for my GTM engine, my question is, is it ok to regrind to +10 on a race engine? as I have to use 1 1/4" SU's I can't see it revving much past 7000 rpm. I read somewhere that a 10 thou regrind has a negligible affect on the strength, is that true? Also on the same theme, is a centre strap necessary on a A+ block?

 

Ta

S



#2 Dusky

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Posted 20 March 2018 - 10:40 AM

Nothing wrong with a regrind.
I dont like centerstraps, they re way too expensive after line honing and do nothing some hardened washers couldnt do. Wich is what I use

#3 Northernpower

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Posted 20 March 2018 - 10:43 AM

If you talk to Keith Calver, who's built a few race engines in his time, he doesn't fit a centre strap, just some APR washers on the main bolts.



#4 racingbob

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Posted 20 March 2018 - 11:27 AM

my historic 1293 Cooper s was ground 10 thou no problems

#5 grizzler73

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Posted 20 March 2018 - 12:45 PM

I have to admit I was never convinced by the centre main strap as an idea anyway, the A+ one looks very strong. Can you clarify the washer comments? Do you add the ARP washers instead of the lock tab, any loctite used on the bolts?

Thanks



#6 Northernpower

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Posted 20 March 2018 - 01:46 PM

No locktabs and no locktight on the bolts. You'll probably have to grind the end cap heads down a little to give clearance on the box due to the extra thickness of the washers.

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#7 hhhh

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Posted 20 March 2018 - 02:21 PM

Why no Loctite? Thanks.



#8 Steve220

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Posted 20 March 2018 - 02:24 PM

Why no Loctite? Thanks.

 

You won't get an accurate torque.



#9 hhhh

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Posted 20 March 2018 - 02:32 PM

That makes sense that it would change the net clamping force, but I'm sure some engineer somewhere could calculate the adjustment required though for the wet torque. According to this: http://henkeladhesiv...ationship-2.pdf , torque is more consistent with Loctite than without since it reduces variability.


Edited by hhhh, 20 March 2018 - 02:37 PM.


#10 nicklouse

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Posted 20 March 2018 - 02:40 PM

always run a strap on both A and A+ but we were/are pushing 8.5k



#11 Northernpower

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Posted 20 March 2018 - 02:48 PM

always run a strap on both A and A+ but we were/are pushing 8.5k

If I were revving to 8.5k I'd be like you and fit a strap but the OP says he's only going to rev to 7k. A complete balance would be better value than fitting a strap.



#12 nicklouse

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Posted 20 March 2018 - 02:51 PM

 

always run a strap on both A and A+ but we were/are pushing 8.5k

If I were revving to 8.5k I'd be like you and fit a strap but the OP says he's only going to rev to 7k. A complete balance would be better value than fitting a strap.

 

I would not not balance it anyway whatever the RPM I doubt the last build I did will see 6k but was fully balanced. (no strap by the way).



#13 Northernpower

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Posted 20 March 2018 - 03:57 PM

 

 

always run a strap on both A and A+ but we were/are pushing 8.5k

If I were revving to 8.5k I'd be like you and fit a strap but the OP says he's only going to rev to 7k. A complete balance would be better value than fitting a strap.

 

I would not not balance it anyway whatever the RPM I doubt the last build I did will see 6k but was fully balanced. (no strap by the way).

 

I don't understand, why wouldn't you balance the bottom end of an engine?



#14 grizzler73

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Posted 20 March 2018 - 05:07 PM

 

 

always run a strap on both A and A+ but we were/are pushing 8.5k

If I were revving to 8.5k I'd be like you and fit a strap but the OP says he's only going to rev to 7k. A complete balance would be better value than fitting a strap.

 

I would not not balance it anyway whatever the RPM I doubt the last build I did will see 6k but was fully balanced. (no strap by the way).

 

 

I think Nicks use of a double negative confused you, that is generally what they do  ;D



#15 Northernpower

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Posted 20 March 2018 - 06:43 PM

Ok I understand, I just misread it; doh!




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