ConcoursMustang Forums
Restoring - General discussions that span across many different groups of years and models => Processes, Products & Techniques => Topic started by: jwc66k on December 15, 2014, 08:36:14 PM
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I've asked around, including a PM on this subject, and still have questions. In net searches, it appears that Heli-Coil is owned by a company in India, and "simple" technical data is lacking, torque specifically. There also appears to be no US sales representatives for Heli-Coil, only distributors that sell Heli-Coil and I would prefer to talk directly to a Heli-Coil rep.
The subject: a 66 289 "C" code with a stripped head bolt on number 4 cylinder, the upper outside hole. It's a 7/16-14 thread and Heli-Coils are available in that size.
The question are:
- Will the Heli-Coil work?
- Will the Heli-Coil take the 70 foot-pounds of torque per Ford requirements?
- What material Heli-Coli, stainless?
Are there other remedies?
The question is rhetorical, a different solution was used.
Jim
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I helicoil will work and will be stronger than the original thread if installed correctly.
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In my 25 years as a tool designer I can't think of one instance where we used heli coils to repair heavy duty threads. We always use threaded inserts (key inserts) for high torque applications. It is also standard procedure to use threaded inserts in aluminum if you have screws that will be removed repeatedly. Aluminum threads just don't hold up over time. Here is a link to Carr Lane to see an example.
Bill
http://www.carrlane.com/catalog/index.cfm/26605071F0B021118070C1C510D020609090C0015480013180B041D1E173C1B08535A (http://www.carrlane.com/catalog/index.cfm/26605071F0B021118070C1C510D020609090C0015480013180B041D1E173C1B08535A)
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We always use threaded inserts (key inserts) for high torque applications.
These were considered but thickness of block material near the location of the bolt became a concern. Also, the question was about cast iron not aluminum. The aluminum reference may assist others later on.
I've checked with a couple of automobile machine shops and the use of Heli-Coils was not frequent but was used a couple of times on stripped head bolts. I don't know what the long terms reliability is as the shops didn't know. The general consensus was to get another block.
Jim
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I've checked with a couple of automobile machine shops and the use of Heli-Coils was not frequent but was used a couple of times on stripped head bolts. I don't know what the long terms reliability is as the shops didn't know. The general consensus was to get another block.
Jim
Yes, a rather popular repair on ALUMINUM blocks, I worked at Cadillac (GM factory trained specifically on the 4100 and other engines produced by General Motors) when the aluminum V-8 was introduced (the Vega V-8, we used to called it) and that was a factory approved repair on the 4100 which eventually called out for Torque-to-Yield bolts to help alleviate the problem(s). Those style bolts were beginning to become the common (in the 80's, on most everything) because of the pulled threads, particularly in aluminum. The design is to do a basic torque, in pattern, a low torque value first, say of 45 ft.lbs., then a re torque of say 60 ft. lbs. then a rotate of say 90 degrees,(or 180 degrees) then a final turn of say 90 degrees, the specs varied between locations of torquing and various applications.
I mention the above because of any added friction that might be produced by using a Heli Coil. If it were good enough for warranty repairs, I would think it would be good enough for a basic 289 also.
Personally, on a standard performance 289 2V, and/or a Show Only car, I would use a Heli Coil rather than hunting down another doner block. If it were a Daily Driver or Performance engine or had higher than normal compression ratio, maybe a cause to pause and consider another block first.
Good luck, but if done correctly, you really should have no problems. I might, with using new head bolts and a "test"(sacrificial) head gasket, install the head on the bare block (if you are intending on rebuilding the engine) and "feel" how this one torques as compared to the other head bolts.
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another option:
http://www.timesert.com/
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Looks promising. I'd like to try some of those. Basically a threaded insert that uses a lot less real estate.