Posted: Tue Apr 08, 2008 2:18 pm Post subject: helicoil to head bolts f-head
hello,
in my previous head gasket change,the threads of the block from the back bolt of the engine hook blown up.
the machinist came to my garage and repaired.
now i want to retorque again the bolts to the f-head.and afraid for the same.
can i use helicoil to that?what dimension should i use?because here in Greece we are not very familiar with inches.
i see some kits on ebay.are they worth?
http://cgi.ebay.com/NEW-7-16-20-Helicoil-Thread-Repair-Kit-in-Pouch-5528-7_W0QQitemZ290219448317QQihZ019QQcategoryZ303QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
7/16-20?
7/16-16?
after that i will use thread sealant at the bolt?i have to use red loctite to the helicoil?will the torque specifications be the same?
I would first see if the area around the threaded hole has sufficient material for a solid threaded insert. These seal much better and can stand full torque applications a little better. Also I usually consider switching to a stud when I have to repair threads in head bolt situations. They are not turned in and out so often. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
my machine shop insterted one solid replacement made fron a tube of steel in the lathe.
is it clever to replace all the head bolts with studs?the bolts are old and i'm seeing that i'm starting to have thread problems with the block now.
have you do that?
what type of studs do you say to use?and they will need the same amount of torque?or i will start to experiment?
You must remember the use of studs will make it more difficult to lift the head straight up high enough to remove when it's installed in the chassis. Studs will normally use the coarse NC thread in the block and the Fine NF thread at the top for the nuts. The torque will be a slight bit lower with the fine thread nuts. The coarse threads are only required to screw in completely by hand. If you use studs you can use a harder drying sealant. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
The depth of the hole in the head will give you the necessary grip length (un-threaded portion of the stud). Then measure the length of the current bolt's threaded portion. This is the length of the coarse (NC) (7/16-14NC) portion of the stud. Now the top of the stud's fine threads (NF) (7/16-20NF) must be adequate for the nut and leave at least two threads protruding above the nut when it is torqued. The reason I didn't talk about the thickness of the head gasket is it's my way to make sure the grip length (smooth/un-threaded portion) does not protrude above the top edge of the bolt hole on the head.
You also want to get quality grade 8 studs preferably with a cadmium or similar plating. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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