[SEL] Hercules pistons and bores.

[Peter A Forbes]

On Tue, 11 Jan 2005 12:43:18 -0500, you wrote:

>Hey guys,
>I found the clearance spec sheet that someone posted several years ago 
>in the archives. I just put it on my website if anyone else wants it.
>http://www.oldengine.org/members/holland/images/PistonClearances/PistSpec.jpg
>or  
>http://www.oldengine.org/members/holland/images/PistonClearances/PistSpec.tif
>Curt
>
>Curt wrote:
>
>> Have some questions about the smallest Herc pistons and bores.
>>
>> On the 1 1/2 - 2 HP Herc was the bore exactly 3.250 when new?
>>
>> Measuring an old piston (some wear?) the following measurements are 
>> found:
>> Dia. Skirt is 3.243 (.007 clearance to bore)
>> Dia. Land 3 is 3.238 ( -.005, .012 clearance to bore)
>> Dia. Land 2 is 3.236 ( -.007, .014 clearance)
>> Dia. at Top is 3.232  ( -.011, .018 clearance)
>>
>> Do these clearances seem right for a bore of this size?
>>
>> This engine has been bored to 3.264 (or .014 oversized). I have made a 
>> new piston for it and am wondering if I should simply take the old 
>> piston measurments and add .014 to each measurement, or if I should 
>> make some changes.
>>
>> A long time ago someone posted an old chart showing the correct step 
>> dimensions to compensate for higher temperatures at the crown of the 
>> piston. Is that information still around? Glenn, do you happen to have 
>> any old Hercules information on clearances and steps for these pistons?
>>
>> Looking forward to your thoughts and comments.
>> Curt Holland
>> Gastonia, NC

I have scanned the Hepolite Piston Service Manual page with the recommended
clearances for various piston types and materials:

http://www.oldengine.org/members/diesel/Misc/Piston1Red.jpg

There are also ring clearance details as well.

It is quite a high res scan, but not the original, that was 19mb!

Peter

--
Peter & Rita Forbes
Email Address:
diesel at easynet.co.uk
Web Pages for Engine Preservation:
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