<VV> failed helicoils

[djtcz at comcast.net]

If the main line and cam bores measure straight and the correct sizes it may be worth fixing threads. 

Tap drill for 1/2-13 in aluminum is 27/64  or .422 inch.  EMHART (maker of heilicoils) lists the major diameter of a 3/8-16 helicoil tap at around 0.46 inches, so pulling a 3/8-16 helicoil would leave a hole at least that big.

many Solid inserts are based on a 1/2 inch thread. Normally coarse threads are considered stronger in aluminum. The tap drill for 1/2-13  (coarse) is about 0.422 inch, so there is a pretty good chance the helicoil tore a bigger hole (0.46 +/-) on its way out


Keensert is one brand of thick walled thread repair insert
http://www.kvt.ch/cgi/04medien/medieninfo_0401/bilder_lowres/keensert-72dpi.gif

re-nu-thread is another - 1/2-20 (fine) outside thread - http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=365&PARTPG=N2DRVSH&PMT4NO=24768109&PMITEM=53316865&PMCTLG=00&PMT4TP=*LTIP

http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=2144677&PMT4NO=24768109



Dan Timberlake

-------------- Original message -------------- 
> From: Grant43 at comcast.net 
> Subject: Stripped out helicoil 
snip - 
> Hello again fellas: 
> Well, my head troubles have been narrowed down to three stripped head stud  casings and a broken lifter. ..... So... what do you do when 
> the case has already been tapped out and repaired and then pulls through again?  Is there an alternative type of repair in this case, do you just use an over sized helicoil for round 2 or do you just make the case a boat anchor? Thanks 
> again! 
> 
> Grant Richardson