[Land-speed] Destroking a Crankshaft...

[Larry Mayfield]

All, Skip, sleeving now is reasonably expensive.  You folk have no idea 
what I am thinking about for the destroked crank, the use there of.    I 
don't want a V6 motor. Sleeving two cylinders and using a 289 Ford crank 
does not get me where I want to be.  A hint, some drag races using ford 
small blocks are using the destroked cranks to make a high winding motor 
that has enjoyed some success, or at least I am told that. drag 
racing...hmmmm


I do want to thank everyone who did respond to the actual question 
though. And that was the practice of welding up a crank so that it's 
stroke could be changed, either more or less.  There were not many of 
you who did that though. Your answers confirmed my suspicions that this 
was not necessarily a good practice to follow.  I was not leaning that 
way but had had some folk chime in that it could be done quite easily 
and was a good choice.  Maybe if no other solution is available at all..

mayf

On 2/22/2011 6:46 AM, Skip Higginbotham wrote:
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> Easier and more economical to sleeve and pin all eight or even just a 
> couple of cylinders. As far as the crank is concerned, you might 
> offset grind it and chrome it back to -.020.
>
> Skip
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> At 10:34 AM 2/20/2011, Larry Mayfield wrote:
>> I have been toying around with an idea for a new motor for my Sunbeam.
>> But it would require a destroked crank to meet the displacement 
>> goals. I have been searching around for such cranks and they are 
>> pretty rare. Some are apparently used in a Nascar class somewhere 
>> which has a displacement limit.  I know about off set grinding to 
>> either stroke or destroke abit.  But, even with a brand new crank, I 
>> would not be able to get there.  So, my question... I know cranks can 
>> be welded up and reground. But how much can that be used?  If I 
>> wanted to take a crank down with a stroke difference of say 1/2 inch? 
>> That seems like a LOT, lol, as it would require a 1/4 inch or more of 
>> buildup on the inside of the rod  throw.   Even if I started with a  
>> 289 ford crank it would still be a lot.  And is that even doable with 
>> a cast crank?  I would expect it to be ok on a forged steel or billet 
>> crank, though.
>>
>> I'd like some responses from folk who have actually had something 
>> like this done.  Suggestions of changing motor blocks etc are not 
>> what I am looking for.
>>
>> And I am just fiddling around now. The Sunbeam may never run again as 
>> a race car..and that would no doubt please a LOT of people, lol...
>>
>> mayf