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Discussion Starter #1 (Edited)
Hi All,

I wanted to post this in hopes that others can avoid ruining their blocks with crappy Chinese taps brands that have poor or next to no quality control regarding their products. To make a long story short, I had drilled and tapped my block stud holes to prepare for time sert installations. On the first attempt to install the time sert, it noticed how sloppy the newly threaded hole was against the time sert. At first I thought it was because the last three thread revolutions on the cert expand, but such was not the case. Every type of M12x1.5 bolt had the same kind of slop.

I went back to the parts store selling these taps to double check to see the other taps being sold were oversized, and sure enough, they all were.

The tap measurements were M12 x 1.5, and that means the tap is supposed to be 12mm in diameter? This tap measured 12.079mm flat and 12.11 (as you rotate the tap). That doesnt seem like much, but when you consider the true OD of a M12 bolt measures on average at about 11.84mm. The difference is 0.239mm. The slop is very noticeable.

I suppose the next questions; do I attempt to install the time serts and torque the head down? What would you do in a case like this?
 

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Damn, that's brutal.

'fit class 5' I guess.

In your shoes, I think I'd try it, fully expecting it to fail. Maybe an industrial high- temp epoxy?
OR an oversized time- sert, if they make such a thing. Give the company a call- I'm sure they've
seen this before, and maybe they'll have some better advise.

I have to admit, I've been checking fasteners recently, after a bad experience with some low-
quality studs, but I wouldn't have necessarily thought to check a tap.

Outsourcing is good for... profits.
Anyone who tells you differently may not be selling something.

t
 

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I would install the m10 Big-Serts using kit 1090BS. This kit includes the proper drill, tap, jig, and threaded insert to save your block.

I do have the kit which I loan out to fellow forum members for a modest fee... PM me if interested.
 

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Discussion Starter #4
I would install the m10 Big-Serts using kit 1090BS. This kit includes the proper drill, tap, jig, and threaded insert to save your block.

I do have the kit which I loan out to fellow forum members for a modest fee... PM me if interested.
I'm extremely interested. PM sent!
 

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I would install the m10 Big-Serts using kit 1090BS. This kit includes the proper drill, tap, jig, and threaded insert to save your block.

I do have the kit which I loan out to fellow forum members for a modest fee... PM me if interested.
I'm extremely interested. PM sent!
I was going to suggest that was a perfect solution for you. :thumbsup:
 

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I don't think the tap bit had caused the sloppy. If you drilled and tapped on a solid block of aluminum, the timesert would not be such sloppy using the same tap bit. The difference is that the engine block old threads after drilling out made a slightly larger hole compared to a solid block. Was the installed Timesert (the Timesert driver expanded the Timesert bottom few threads to lock it) able to backout or locked in the tapped hole? If it locked then it is not that loose.

I would just clean the block threads really good with acetone or alcohol then coat the hole threads and Timesert with JBweld and install the Timeserts. It is good idea to JBweld the timesert threads anyway.
 

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This is the first time I even hear someone to try to prep holes for installing Time-sert sleeves using a non-original tap.

It's ok to use non-Timesert drill bits of the same diameter, you may even get away with different brand drivers. But the tap itself shouldn't be anything but Timesert, especially in head bolt or spark plug applications.

Luckily there is enough space to go with Big serts in this case...
 

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The tap measurements were M12 x 1.5, and that means the tap is supposed to be 12mm in diameter? This tap measured 12.079mm flat and 12.11 (as you rotate the tap). That doesnt seem like much, but when you consider the true OD of a M12 bolt measures on average at about 11.84mm. The difference is 0.239mm. The slop is very noticeable.
You don't understand thread cutting and thread clearances. The tap will be noticeably larger than the corresponding bolt 100% of the time!!!

You didn't explain what you actually did and what went wrong. I assume you were trying to clean up a threaded hole.

1. We can assume the thread already had damage if it needed cleaning up. How much material came out with the bolt that was in that hole?
2. Did the tap start correctly?

I could go on and on, but more than likely the hole was already beyond repair, or you didn't use the tap correctly.
 

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Discussion Starter #9
You don't understand thread cutting and thread clearances. The tap will be noticeably larger than the corresponding bolt 100% of the time!!!

You didn't explain what you actually did and what went wrong. I assume you were trying to clean up a threaded hole.

1. We can assume the thread already had damage if it needed cleaning up. How much material came out with the bolt that was in that hole?
2. Did the tap start correctly?

I could go on and on, but more than likely the hole was already beyond repair, or you didn't use the tap correctly.
Go back to the my original post and re-read it. I know it may be complex for you, but try again.
 

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While an M12x1.5 tap is pretty close to the specified M10x1.5 STI tap, it's about .006" larger on pitch diameter at the upper end of the tolerance. That may not seem like much, but for pitch diameter it is. If the shop failed you, it was specifying the wrong tap. The correct tap would be marked "M10x1.5 STI"
 

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Hi All,

I wanted to post this in hopes that others can avoid ruining their blocks with crappy Chinese taps brands that have poor or next to no quality control regarding their products.

Avoid these bastards at all cost:

http://www.centurydrill.com/
Well, you used the wrong tap. According to Time-Sert datasheet, for M10x1.5 time-sert the correct tap major diameter is 0.474" or 12mm measured. Your tap is too big but it's not the manufacturer error; it's you.

https://www.timesert.com/html/catalog.pdf

BTW, your photo shows the tap was made in Japan and not China.

What is the length of your Time-sert?
 

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Discussion Starter #13
Well, you used the wrong tap. According to Time-Sert datasheet, for M10x1.5 time-sert the correct tap major diameter is 0.474" or 12mm measured. Your tap is too big but it's not the manufacturer error; it's you.

https://www.timesert.com/html/catalog.pdf

BTW, your photo shows the tap was made in Japan and not China.

What is the length of your Time-sert?
Wow. I ****ed up. I cant believe I used a 12M tap for a 10M thread. Ill be able to use oversized time serts on the holes for a massive fail recovery.

The packaging on the tap says "made in China".
 

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Wow. I ****ed up. I cant believe I used a 12M tap for a 10M thread. Ill be able to use oversized time serts on the holes for a massive fail recovery.

The packaging on the tap says "made in China".
Don't kick yourself too hard.
I'm sure everyone has had an equally bad "dear god what I have done" moment with e46s.

Well, at least the M12 with have more thread engagement than the M10.
 

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Timesert does a poor job with the tap specs. The kits obviously include the recommended tap. For the sake of this thread the major diameter of a internal M12x1.5 is 12-12.406mm for a 6H tolerance thread. This would be the OD of the tap, but would not define the fit of the thread which is defined by pitch diameter.

http://www.timesert.com/html/faq.html#18

I simply don't buy Chinese cutting tools, unless they are expected to be disposable. Even then, for something like a tap, it would be tested on a piece of scrap first (and pray the tool survives to make more than one part). And *(#$%&^@$* them for making counterfeit and marking other brands and country of origin.
 

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If the new tap strategy creates issues, I want to plug modern epoxies which someone else noted. The epoxies nowadays are stronger than the steel in our blocks. You could likely install the loose time sert with a recommended epoxy and have a crazy strong hole.
 

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Cast aluminum is ~40ksi (275MPa) tensile yield. Epoxy with filler will be maybe 6ksi (41MPa). Add >100°C temperature?? Don't kid yourself, plastic is not metal. For a valve cover stud? Maybe. Head bolts? No way.

Bigsert is the answer.
 
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