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05-29-2020, 09:29 AM #1Member
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Repairing stripped plug holes, round two
After being told that I don't know how to machine or weld, i figured it was time for an experiment. I took three GRM cylinder heads and faced them down for 1/2" reach plugs. The first one was countersunk from both sides and all remaking threads were rotary filed out. Using my Syncrowave 350 I welded as far as I could from one side and then flipped it over and welded from the other side. I then faced off both sides and drilled and tapped 14mm. The threads were perfect, no inclusions in the weld.
Second one I drilled and tapped for a 3/8 pipe plug (not the 1/4 I originally mentioned) Cleaned it up and wound in a brass pipe plug using a dab of Loctite 630. Faced it off and drilled and tapped it 14mm.
The third one I ran the 14mm tap through, but really did not need it.
I then mounted a cylinder in my milling machine vice and bolted on the welded head. I put anti-seize on the threads and face of the spark plug. Using an old Craftsman 1/2 drive torque wrench I would in the spark plug. The threads failed at 35 foot pounds.
I then mounted the original thread head. Got to 55 foot pound and broke the spark plug. I then welded a nut to the end of my 14mm arbor. It made it to 80 foot pounds.
The brass pipe plug repair went 100 foot pounds without failing, but my arm was done. I am going to try attaching pictures, but I am much better building race motors or driving race boats than I am on a computer.
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05-29-2020, 09:35 AM #2Member
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Like I said, not that good on computer.
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05-29-2020, 11:21 AM #3Member
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h
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05-30-2020, 05:53 AM #4Member
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rgsauger liked this post
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05-30-2020, 06:15 AM #5Member
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rgsauger liked this post
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05-31-2020, 06:48 AM #6
Ive worked in the industrial repair field for almost 40 years as a welder and a machinist and repaired countless threads using many different methods. Somehow I never thought of this one.
I like itlimited skills
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rgsauger liked this post
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05-31-2020, 07:29 AM #7
Mike, even though your repairs with the brass plug look great, and I would run it any day, you STILL don’t know how to machine or weld!!!
1990 Shadow bass boat w/ 2.4 200 Merc. Totally resto'd boat and love it!
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05-31-2020, 10:31 PM #8
You could have made a slug out of Inconel , and maybe went to 300 ft/lbs … but what's the point.
Most sparkplugs seat at 20 ft/lbs .. you have a 15 pound cushion .
#1 ) Are you happy with that .. ?
#2 ) I'll ask again .. what size was your finished hole ?
#3 ) What size tap did you use .. ?
#4 ) The hole you chased , did the tap go through by hand or did you have to drive it .. ?
It's not personal .. it's just metal .
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06-01-2020, 06:46 AM #9Bud Conner "Heathen" "Defending Our Constitution"
FOR ALL ENGINE APPLICATIONS
DRY Film Lubricant for Piston Skirts & Cranks + Thermal Barrier Ceramic Coatings for Piston Tops, Combustion Chambers, Valves etc !!
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06-01-2020, 02:59 PM #10
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06-01-2020, 05:24 PM #11
Cool experiment, thanks for doing it and posting it! I don't have any skin in this game, or any opinion to share on the subject but its a cool test and thank you for doing it!
www.InjectorService.com
Call/Text - 204-326-0390
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06-01-2020, 06:01 PM #12Member
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1 No. When we tow 1000-1500 miles to race, the last thing I want it to pull the threads out of a plug hole.
2 Ran a 31/64th drill through. Correct tap drill is 12.8mm (.504") If you measure a fresh cylinder head the I.D. of the threads measure .488". I have been using 31/64th (.484") since the mid 70's when I started building Konig cylinder heads.
3 Just a generic 14 x 1.25 McMaster Carr 4 flute tap. Bought a new one for this experiment.
4 Started it with a T handle tap wrench and ended up running it through by hand (no wrench at all) took out dust.
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loop liked this post
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06-01-2020, 11:20 PM #13
#1 ) I agree 110% For me it was about melting the plug mushrooming what's left of the body to where it wouldn't come out .. same end result I reckon ..
#2 ) I think you'll find the when the hole is properly sized , the tap will "roll" a bit of material to the peak .
#4 ) I know , I cant count .. My problem was I would run a tap thru a perfect plug hole and it would take out material … that was my clue I needed to learn about taps .
#3 ) Yes , my beloved McMaster Carr .. is limited in scope to what's needed.
I did buy a "good" 12.5 mm drill bit from them .492"
A .500" and a .503" ream from them to go along with a set of adjustable's I already had . I like going in a bit of undersize as well , and only used the .503 a couple of times . I try to go slow and keep the wibble~wabble to a minimum . My .500" comes out as aprox .501 and it's not going on the Space-X … More effort than most people put into sizing a hole . My friends say I need to get out more often ..
The sizes you mentioned , are right in line with the parameter's on the McMaster page. You left out the key ingredient …
Where it says : "pitch diam. limit" D4
They are speaking of : "class of thread"
Murican , threads are L for low H for high.
Fer~in~orr , threads are U for low D for high.
CHART 1A Pitch Diameter Limits for taps to 1" diameter inclusive:
L1 = Basic to Basic minus .0005
H1 = Basic to Basic plus .0005
H2 = Basic plus .0005 to Basic plus .0010
H3 = Basic plus .0010 to Basic plus .0015
H4 = Basic plus .0015 to Basic plus .0020
H5 = Basic plus .0020 to Basic plus .0025
H6 = Basic plus .0025 to Basic plus .0030
Taps larger than 1" dia. are ground to a .0010” tolerance on the pitch diameter and are, for example, H4 (Basic plus .0010” to Basic plus .0020” ).
CHART 1B Pitch Diameter Limits for taps to 1" diameter inclusive:
(Metric taps generally have more manufacturing tolerance than .0005 to the minus side.)
U1 = Basic minus .0005 = min. tap P.D.
D1 = Basic plus .0005 = max. tap P.D.
D2 = Basic plus .0010 = max. tap P.D.
D3 = Basic plus .0015 = max. tap P.D.
D4 = Basic plus .0020 = max. tap P.D.
D5 = Basic plus .0025 = max. tap P.D.
D6 = Basic plus .0030 = max. tap P.D.
A 14mm plug is really 13.8 mm in diam. .5433
14 mm = .5512 + D4 .002 = .5532 - .5433 = .0078
Looks like .008 to .010 on a good day ...
My experiment was to buy from a little higher on "Dee" list ...
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06-02-2020, 04:58 AM #14
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06-02-2020, 02:31 PM #15
It's printed on the back of the Sonny's BBQ menu, under "good ol boy tips and tricks"
Speakin of tips … Here is why "maff" is so important …
Maybe another reason ...
Lets just say these new billet heads were machined in China or Crackistan ..
Don't really like the exposed threads ( detonation starters ) but it is what it is. And I can always blend them in .
Need to cc the chambers to see where we're at ...
The magic bubble that never goes away ...
And What The _ _ _ _ Heck is running down my arm ...
Gotta be Crackistan ..
Little mud-dobber action should hold long enough to get a measurment ..
These POS things were held in place with a hollow roll pin that went within one ta two threads from entering the chamber .. can't make this $hizzle up ..
Now that the garbage has been taken out to the dump .. How am I gonna keep these masterpiece's from warping ... Ohh this looks like a good fixture, with the water cover off .. they fit either , flipped or flopped ...
While inserts might work for some .. And yes I have all the popular ones and even some that went out of buizz decades ago … I usually see the tard side of installations .. so forgive me for being a bit biased ..
A new start , for a new part ...
P.S. Chaz = thinkin, I really like how tungsten-carbide bits .. cut …
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