Spark Plug Thread Re-Tap - Chevelle Tech
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post #1 of 20 (permalink) Old Apr 8th, 20, 1:14 AM Thread Starter
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Steve
 
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Unhappy Spark Plug Thread Re-Tap

Hey its been awhile. Was checking my plugs on aluminum head 427 BB and the helicoil insert thread came out with the plug. This is on # 7 way back of motor. I do not think I can replace with the same insert .

What is correct action to take short of pulling the head? There wont be any way to smack on an insert thread having no smack room at the back of the motor.

Any different brand or product someone out there has tried. I am looking at time sert 4412 / M14 but rather pricey for the insert and tap kit.

Thanks all and stay safe

( we need all you seniors healthy to keep this thing going)
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post #2 of 20 (permalink) Old Apr 8th, 20, 5:58 AM
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Re: Spark Plug Thread Re-Tap

OUCH! This really ought be in the Engine forum to get more views, esp from the professional machinists. Last time I helicoiled heads was in 1993, and I do recall setting the helicoils somehow so they cant spin out.

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post #3 of 20 (permalink) Old Apr 8th, 20, 7:01 AM
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Re: Spark Plug Thread Re-Tap

Is this a "normal" Helicoil, the type that looks like a spring ? Or one of their "sav-a-thread" kits with the solid insert ? If it is the solid insert I would just put it back in and dont worry about it for now. Maybe put some High Temp Red Loctite on the outside of the insert and hope it stays in next time.

Since it has already been repaired once, the only Timesert kit that is going to work will be a "Bigsert" and I would not recommend trying that with it on the car.
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post #4 of 20 (permalink) Old Apr 8th, 20, 12:13 PM Thread Starter
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Re: Spark Plug Thread Re-Tap

It was a solid insert installed at the machine shop , not the spring type
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post #5 of 20 (permalink) Old Apr 8th, 20, 12:27 PM
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Re: Spark Plug Thread Re-Tap

I used the Time-serts for my BMW after a shop messed up the threads. Bought them off Amazon. Pricey but cheaper than pulling the heads.

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post #6 of 20 (permalink) Old Apr 8th, 20, 12:29 PM
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Re: Spark Plug Thread Re-Tap

Quote:
Originally Posted by 427elco View Post
It was a solid insert installed at the machine shop , not the spring type

If it is the solid "Sav-A-Thread" insert with the "teeth" around the top that are supposed to lock it in place then I would just put it back in with the plug and run it for now. I personally hate them and would never use one. Once the head has been tapped oversize for that type of insert it is very difficult to make a Timesert work. The timesert tooling depends on the original threads to keep it centered while you cut the counterbore for the top of the insert. You can do it on the bench but I cant imagine trying to do it with the engine in the car.

Bill Koustenis
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post #7 of 20 (permalink) Old Apr 8th, 20, 2:39 PM
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Re: Spark Plug Thread Re-Tap

Well elco heres my two cents on this i agree with a lot of what bill k has to say but i would like to say a few things .if its a pring type helicoil its a 3/4 reach. Who installed this originally? Maybe it was installed wrong . Sometimes on a spring type you have to cut a few threads off it so it wil fit properly i have seen people cut off the bootom with a sharp pair of diagonal cutters and ruine it then grind so it will go in . Thats wrong you cut off the top with a disc and dremel ot th like so its clean that bottom piece you break off is the lock for the coil. If thats the case i would try another. If its what i call the sleeve type like timezert or the k / d tools one what i found works well with the k/d one is when you install it use red or green locktite on the outside threads. When you install it use a new gasket on the bottom of the spark plug and tighten it down good so the gasket mashees the lip down good . Let it sit a minute then use an air gun to quickly remove the plug. Once the plug is out heat the area with a smll torch just get it warm and that locktite wont let it back out . I have never had one come out on me and i have done many. Infact i had a pretty good reputation with my customers for getting out brocken bolts exhaust studs stripped thread plugs broken off in the car etc . I would take my tools to the customer and tell him leave me alone i need acord light and air. This is probably because when i worked in my uncles machine shop there would be days that i would spend ten twelve hors doing just that on job after job . Some days it would be boring clys all day or sets of connecting rods all day. Monotonous yes but i thank him for teaching me and all the little tricks when all else fails. I learned a lot from him and all the other first class machinists that woked for him. We fixed and rebuilt every thing from an allis chalmers to a waukeshaw. My uncle once told me " we have done so much with so little for so long that we can now do just about anything with nothing . In his case that happened to be true. Alex
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post #8 of 20 (permalink) Old Apr 8th, 20, 3:05 PM
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Re: Spark Plug Thread Re-Tap

I am pretty sure this is what he has except longer:
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Bill Koustenis
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post #9 of 20 (permalink) Old Apr 9th, 20, 2:57 AM Thread Starter
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Re: Spark Plug Thread Re-Tap

Yep that's the one . My threads are torn up on it , should I try a fresh one?
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post #10 of 20 (permalink) Old Apr 9th, 20, 7:02 AM
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Re: Spark Plug Thread Re-Tap

Quote:
Originally Posted by 427elco View Post
Yep that's the one . My threads are torn up on it , should I try a fresh one?

Thats about all you can do. If the threads on the insert are messed up, how about the threads in the cylinder head ? Can you post a picture of the plug with the insert that came out ?

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post #11 of 20 (permalink) Old Apr 9th, 20, 12:26 PM Thread Starter
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Re: Spark Plug Thread Re-Tap

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post #12 of 20 (permalink) Old Apr 9th, 20, 12:31 PM Thread Starter
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Re: Spark Plug Thread Re-Tap

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My machine shop pal says I can borrow his kit ( spreader ) to save costs. do I need to recut or chase the threads ?

Where to buy this insert economically?

What thread locker do I use ?

Thank You

SK
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post #13 of 20 (permalink) Old Apr 9th, 20, 1:04 PM
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Re: Spark Plug Thread Re-Tap

Steve,

The tool in your picture is the Timesert tool and will not work with the insert like you have. The insert you have uses a tool that you just smack with a hammer and it expands the toothed part of the insert. The Timesert is a totally different approach and they are not interchangeable. I dont think the entire Sav-A-Thread kits are very expensive anyway. You can probably buy the whole kit for $30 Do you know anyone at an auto repair shop ? A lot of those guys use the type you have because they are cheap and easy. Maybe someone would loan you the tool.

Almost all of the parts stores sell the kits. I know Advance Auto and Autozone have them in my area. I would bet they would have the inserts separately also. If you can find some High Temp Red Loctite that would be best but regular red will probably be ok too.


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Bill Koustenis
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post #14 of 20 (permalink) Old Apr 9th, 20, 1:50 PM
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Re: Spark Plug Thread Re-Tap

Are you anywhere near North Jersey or NYC I could loan you that tool if you need it.

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post #15 of 20 (permalink) Old Apr 9th, 20, 2:43 PM Thread Starter
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Re: Spark Plug Thread Re-Tap

Its the smack part Im worried about

don't think I can get a good whack at it down at #7
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