Help a metric person with a tap size on US engine

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cmyers_uk

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Hi, 2000 4.3GL PEFS S/N 4012018114

I took out the cylinder block drain plugs for winter and need to clean the threads to put new plug (part no 3850802) back in. Been to local tool shop and cant find anybody helpful that can tell me what tap I need. I want buy a blue point or snap on set but have no idea what type of bolts , plugs etc the engine has. Can somebody point me in the right direction please , even better does anybody know what tap I need?

Any help on a set that would cover me for this engine greatly appreciated. I have slowly brought tools but taps are what I need.

Many thanks
Chris
 
Bondo

Bondo

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Re: Help a metric person with a tap size on US engine

Ayuh,...

The Drains are tapered Pipe threads,... Either 1/8", or 1/4" Pipe....

Most of the Snap-on/ Blue point sets will have All the usual taps,+ dies...
In my set, there's the 1/8" pipe tap, but no 1/4" pipe tap...
 
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WizeOne

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Re: Help a metric person with a tap size on US engine

NPT, I believe, is the correct designation for the tapered taps that Bondo-o speaks of.
 
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cmyers_uk

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Re: Help a metric person with a tap size on US engine

Thank you , I now know there is a pipe thread, I assume its NPT? I have measured the plug and the bottom is 0.52 inch and the to is 0.54 inch so would that be 1/2 inch pipe NPT?

Thanks again Im sorry that Im really slow at picking this up but its threads are something I cant get my head around what with Metric , Imperial , now pipe and then the different pitches. I wish when I brought the plugs it just told me the thread !

Cheers
Chris

(Sorry wiseone are posts crossed. Thanks so that confirms NPT!)
 
bigbob_FTW

bigbob_FTW

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Re: Help a metric person with a tap size on US engine

yes its a 1/8-27 npt or a 1/4-18 npt.
 
Fishermark

Fishermark

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Re: Help a metric person with a tap size on US engine

cmyers_uk said:
I have measured the plug and the bottom is 0.52 inch and the to is 0.54 inch so would that be 1/2 inch pipe NPT?
Click to expand...

Actaully that sounds like it makes sense... but that would make it too easy! :D Pipe is measured different ways depending upon the material - copper pipe, galvanized, etc. Bottom line - you do not want a 1/2 tap, you want the 1/4 X18 NPT (National Pipe Taper) that Bigbob mentions.
 
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cmyers_uk

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Re: Help a metric person with a tap size on US engine

Your all very kind thank you . Ive ordered a set with 1/4 NPT X 18 and 1/8 NPT X 27.

Thank you all you put a real smile on my face, had one of those mornings but now smiling.

Cheers

Chris
 
fat fanny

fat fanny

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Re: Help a metric person with a tap size on US engine

Remember when driving a pipe tap into the hole only go in about 7 to 8 threads in on the tap so as to maintain the taper for the plug or you will just end up with a tapped hole to the size of the tap no taper. A good rule of thumb just go in in increments of 3 threads each time and back out especially in cast test fit plug each time until you get about 2/3's fit snuggly.
 
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cmyers_uk

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Re: Help a metric person with a tap size on US engine

Thank you for that tip. I hadnt given that any thought. Youve saved me a costly mistake. Thank you

Chris
 
Don S

Don S

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Re: Help a metric person with a tap size on US engine

One other note. When you take a pipe plug out to drain the engine, after draining, put the plug back in with a little grease. Keeps them from rusting up the threads and needing to be tapped each time. A quarter turn from solid should be enough to clean the threads.
 
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