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Auto/Truck/Other Transportation If you use it to get from here to there, this is the place to talk about it and how to fix it.

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Old 11-22-2014, 08:44 PM
sethwyo sethwyo is offline
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Default size of holes ~ size of threading tap ?

If I drill a 7\8 inch hole~ what size threading tap needs to be used ? & what size hole will I have after the thread is cut ? Will it be one inch ?
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Old 11-22-2014, 10:14 PM
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Tim Horton Male Tim Horton is offline
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http://en.wikipedia.org/wiki/List_of..._and_tap_sizes
===
Here is just one of many charts available for tap/drill sizes...

Several of the secrets of drilled/taped holes are the correct hole size...
Strait hole through the material... Round hole as opposed to egg shaped etc... Yes drilled holes can be egg shaped, barrel shaped, hour glass shaped....
Always choose a quality brand name drills and taps... Even for 1 or two holes it is worth the price of good cutting tools...

Keep the tap strait to the hole, and use lots of cutting oil...

For your 1" taped thread, a 57/64" diameter hole would be better.... If your material is thinner maybe up to 1/2 thick, the 7/8" diameter hole would be OK... If your material is 1" or better thick, use the bigger drilled hole...

I got a BIG share of my tuition paid to machinist school by writing papers on drilled and tapped holes... The people reading the papers didn't know squat about drills or taps, but the Ts were crossed, punctuation and spelling were good... They were more into form than content...

Good luck....
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Old 11-22-2014, 10:51 PM
sethwyo sethwyo is offline
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the hole will be drilled cut into an aluminum head on a engine. then a one inch bolt is going to be cut off and modified to be threaded into the hole. the 1 inch bolt will have a hole cut in the middle of it that will also be threaded out on the inside to accept the spark plug.
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Old 11-25-2014, 08:49 PM
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-hope you haven't started drilling yet.

Helicoil makes spark plug thread repair kits: http://www.stanleyengineeredfastenin...pes/spark-plug

-makes it a lot easier. I'd be worried that the material in the bolt and the Al head would have different expansion rates on heating and lead to damage of the head. The HeliCoil avoids that problem and is a lot less work.

Last edited by doc; 11-25-2014 at 08:59 PM.
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Old 11-29-2014, 10:08 PM
sethwyo sethwyo is offline
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thank you for the link with the info.
The problem I have with the vehicle started out when its previous owner did not know to put a threading dope on the spark plugs when he put them into the aluminum head, then when the spark plug got jammed up in the alunimun head, as they always do, he broke off the spark plug in the head. then a drill bit was drilled through the middle of the spark plug leaving it a hollow sleeve stuck inside of the head .an 'easy out' was then driven into the hollowed out spark plug.
and he broke it off , the easy out , inside of the spark plug inside of the hole in the head, the easy out, the broken easy out, is there such extremely hard material that it cannot be drilled or ground out.

I figured to use a hole saw to cut the whole mess out of the head then fabricate a type of sleeve, that a new spark plug to be threaded into, to get the vehicle back on all cylinders again.

no, it was not I that broke off the easy out, or the spark plug in the first place. I have not yet cut anything into the engine block or done any real work on the vehicle.
I want to make sure I have a good method of repairing it before I do anything.
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Old 11-30-2014, 06:48 PM
oeb oeb is offline
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Default How 'bout a used replacement?

Aren't junk yard heads of servicable quality available for your engine? I'm thinking they probably are and you may want to consider using one to solve your problem if you can't get a threaded hole correctly done in your old one.

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Old 11-30-2014, 07:35 PM
Mad_Professor Mad_Professor is offline
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If you remove the head you should be able to drive the broken easy out, out.

Drill out most of what is left of the plug (left hand bit if you have one) and get the rest with another easy out.

Repair threads with a timesert or helicoil

http://www.timesert.com/html/install.html
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Old 12-01-2014, 01:48 PM
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Quote:
Originally Posted by sethwyo View Post
thank you for the link with the info.
The problem I have with the vehicle started out when its previous owner did not know to put a threading dope on the spark plugs when he put them into the aluminum head, then when the spark plug got jammed up in the alunimun head, as they always do, he broke off the spark plug in the head. then a drill bit was drilled through the middle of the spark plug leaving it a hollow sleeve stuck inside of the head .an 'easy out' was then driven into the hollowed out spark plug.
and he broke it off , the easy out , inside of the spark plug inside of the hole in the head, the easy out, the broken easy out, is there such extremely hard material that it cannot be drilled or ground out.
.
...and I don't know why she swallowed that fly. I think she'll die. The first owner obviously didn't know The Prime Directive of mechanical work: Never force anything. If it won't go, get a bigger hammer.

Bummer. Try putting a torch to the mess. The diameter of the spark plug hole is larger than the diameter of the spark plug, so it'll expand slightly more with heat. Maybe then you can give it a twist with an easy-out- or is there enuff of a stump protruding that can be grabbed with a visegrip? Can't you get a socket & impact wrench on it?

The HeliCoil is basically a ready made insert like the one you're proposing to fabricate.

As mentioned above, it's probably easier to work on this on a bench after removing the head [and safer if you're going to take a torch to it.]

Last edited by doc; 12-01-2014 at 01:55 PM.
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Old 12-02-2014, 09:38 PM
jvcstone jvcstone is offline
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sounds to me that it might be more cost effective to take the head to a machine shop and have someone with the right tools do it for you--or as suggested a scrap yard head, although it would probably need machining also.

JVC
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Old 12-03-2014, 03:09 PM
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Quote:
Originally Posted by jvcstone View Post
sounds to me that it might be more cost effective to take the head to a machine shop and have someone with the right tools do it for you--or as suggested a scrap yard head, although it would probably need machining also.

JVC
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Old 12-11-2014, 10:40 PM
sethwyo sethwyo is offline
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When a car was older than me, taking the head off & putting it back on was a job I could handle.

Now that the car is younger than me, taking the head off is not easy.

The cam shafts are in the head, the timing gears are in the head.
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Old 12-11-2014, 11:04 PM
jvcstone jvcstone is offline
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Know what you mean--I don't know what I'm looking at under the hood anymore. Try to keep a banger around (currently a 64 dodge D-100 PU) which is still younger than me by nearly 20 years, but has all the fundamentals--spark and fuel means a running engine -- rough running maybe,--but fixable under the old shade tree. My 1990 F-450 diesel on the other hand --I can't even see under the hood unless I'm up on a stool.

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