Strange spark plug problem. I can't get #3 threaded in properly.

[toolmanmike]

YES! I believe that I'm going to have to use the "reverse thread chaser" that was linked to, it has a center fluted "spreader" that appears to allow the threaded end to be inserted into the spark plug hole, then as the fluted part is pulled into the 4 way split threaded area, it expands the diameter to fit into the threads. Rotate ccw as though you're removing it, and it "cleans" the threads on the way out, WITH the several times recommended grease to grab the shrapnel.

I've had no problem with Autolites, a significant number of Mopar people use them, my local engine builder recommended them, as did a couple of other "gurus". I have a 572 in the process of getting all the components together to have built, and the builder in Florida has a lot of them, and more are paid for, still more to buy, but the point is I hope to retire the 440 within the next year. The aluminum block and heads in the 572 will eventually get either platinum or iridium spark plugs, but I may start with Autolites until I have my A/F ratio and heat range figured out. I will very likely use spark plug specific anti seize on them.

If the old plugs screwed in and out with ease, Your new Autolite plug is the issue. If it were me I would try a different plug (or a different set of plugs from a different manufacturer.

 

[4406bbl]

You need to start measuring spark plugs now, I just put a set in some aluminum heads, one would not tighten up. Pulled it back out and the threads in the head looked perfect. It turns out the new plugs were .030 smaller than the champions I took out.

 

[toolmanmike]

You need to start measuring spark plugs now, I just put a set in some aluminum heads, one would not tighten up. Pulled it back out and the threads in the head looked perfect. It turns out the new plugs were .030 smaller than the champions I took out.

Damn. Exactly my point above.

 

[biomedtechguy]

I am replacing the exact same spark plug as I am installing. I've already successfully installed 2 other cylinders.
Thanks.

 

[dual fours]

Damn. Exactly my point above.

Quality control was 'let go' many years ago.

 

[65Fury440]

A brass brush on a drill, with maybe a 90 degree adapter to gain access to the plug hole might be a good place to start. The brush will pull any leftover thread out, and the direction of the brush rotating will pull the debris out the hole.
As mentioned, try the old plug, and try a couple of the other plugs.
I'd imagine the factory uses dies that can wear out, and stacked tolerances of a marginal plug on a mrginal plug hole could bring you to where you are at now.
Or you could try a 1/2" impact.
Just remember...working on cars is fun.

 

[biomedtechguy]

I'm going to try cleaning out the threaded hole with what I have available that won't be likely to push metal or carbon in to the cylinder.
One more try to thread a spark plug in (or maybe 2 tries) and if that doesn't work, I'm getting the fluted reverse thread chaser.
Thanks again.

 

[biomedtechguy]

you could try a 1/2" impact.

I have a battery powered ½" impact. Using more force isn't the problem, I'm restraining myself from doing that, and making it worse.

 

[toolmanmike]

I'm going to try cleaning out the threaded hole with what I have available that won't be likely to push metal or carbon in to the cylinder.
One more try to thread a spark plug in (or maybe 2 tries) and if that doesn't work, I'm getting the fluted reverse thread chaser.
Thanks again.

I sold many of these over the years.


Amazon product ASIN B001SOHXLQ

 

[RemCharger]

I have a battery powered ½" impact. Using more force isn't the problem, I'm restraining myself from doing that, and making it worse.

That was a joke lol.

A standard chaser with some silicone grease packed in the flutes will work well. There should be next to no filings coming off anyways.
Also, if restricted for room to get the plug in straight, you can put a tight fitting firm rubber hose on the plug, to use as a flexible installing tool.

 

[RemCharger]

 

[biomedtechguy]

That was a joke lol.

A standard chaser with some silicone grease packed in the flutes will work well. There should be next to no filings coming off anyways.
Also, if restricted for room to get the plug in straight, you can put a tight fitting firm rubber hose on the plug, to use as a flexible installing tool.

Yes, lol.
I already tried the rubber hose, and guided the plug with my fingers on my other hand.

I sold many of these over the years

That's the style. Fluted, so it goes in and then the tapered end gets pulled into the split threaded part, spreading it to the right diameter, then reverse it out, with grease on it, and hopefully problem solved.

 

[mopar 3 B]

You need to kick the last person in the (fill in the blank) that installed spark plugs the last time.No reason to be stuck with this kind of stuff.

 

[Don Frelier]

You need to kick the last person in the (fill in the blank) that installed spark plugs the last time.No reason to be stuck with this kind of stuff.

It may be him

 

[Photon440]

You need to kick the last person in the (fill in the blank) that installed spark plugs the last time.No reason to be stuck with this kind of stuff.

He didn't say there was a problem in removing the old plug, and it didn't appear cross threaded.

 

[mopar 3 B]

He didn't say there was a problem in removing the old plug, and it didn't appear cross threaded.

They don't have to be cross threaded if the threads were pulled when the last one was installed.

 

[biomedtechguy]

I installed all 8 last time, roughly 5 years ago, and there's no way I'd cross thread a spark plug.
I cleaned the black off the threads on the Autolite 85 that came out, and the threads look fine, definitely not X threaded, but some debris I will need a pointy thing to clean out of the threads to try to identify. May just be plug thread grease residue, because I used that last time (silver gray sparkley looking, comes in the tiny "bag" hanging by the register of the parts counter) Anyway, the plug was difficult to remove, but I figured it was because it's so hard to get to.
Keep the replies coming, I'll post what I find.

 

[mopar 3 B]

Not sure what the inspiration is to put thread dope on plug threads in a Chrysler cast head. The head was designed for a plug with seal ring. Unlike Cheyby and some Ford's that thought the tapered seat was a better option. Without some type of antiseze they liked to stick. Then some foolishly used the same design with dissimilar metals.
The original Chrysler design didn't require any type of plug lube or sealant and was used for over 30 years. So my question is why now?

 

[1 Wild R/T]

Not sure what the inspiration is to put thread dope on plug threads in a Chrysler cast head. The head was designed for a plug with seal ring. Unlike Cheyby and some Ford's that thought the tapered seat was a better option. Without some type of antiseze they liked to stick. Then some foolishly used the same design with dissimilar metals.
The original Chrysler design didn't require any type of plug lube or sealant and was used for over 30 years. So my question is why now?

The point of Anti-Seize on plugs is aluminum heads, not iron.... Plugs can & do seize and gall in aluminum heads so Anti-Seize is a cheap & easy solution.... And FWIW they sell a copper impregnated Anti-Seize specifically for spark plugs in aluminum heads....

 

[biomedtechguy]

Although I haven't taken "one last try" at cleaning the threads, I went ahead and ordered the reverse thread chaser.
I have the feeling I'm going to need it.
$14 on Amazon with Prime (free trail) delivery tomorrow included.

Not sure what the inspiration is to put thread dope on plug threads in a Chrysler cast head.

I thought it would ease installation and removal.