Z head installed but spark plugs leaking compression now

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Model T Ford Forum: Forum 2016: Z head installed but spark plugs leaking compression now
Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Monday, July 18, 2016 - 11:43 pm:

It seems silly but I'm afraid to tighten more on the aluminum threads. I transferred the plugs from my stock head since they are only a few weeks old.

After warming it up with a first drive I am now wondering if I should crank the spark plugs tighter? I have a history of breaking things and hope to avoid stripping the head.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, July 19, 2016 - 01:52 am:

Wrap white Teflon tape or aluminum foil around the threads.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George n Los Angeles CA on Tuesday, July 19, 2016 - 02:54 am:

I use foil and anti seize


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Tuesday, July 19, 2016 - 07:00 am:

Chris, I would nip them up a bit more once you have run them. If the problem persists, you could try sealing the threads, but it really doesn't matter all that much.

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 07:42 am:

Thank You


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Tuesday, July 19, 2016 - 08:13 am:

Chris:

What spark plugs do you have ??? My experience with the newer reproduction Champion X plugs is that they do have compression leaks due to bad threads.... its probably not your new head threads that are leaking.


Try older Champion X plugs, if you have access. and see if the problem still exists.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Humphrey on Tuesday, July 19, 2016 - 08:19 am:

Just putting in my 2 cents in... Instead of foil wrap some steel wool around the threads of the plug.. I've used this trick many times to tighten up loose threads....and good luck


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Pawelek Brookshire, Texas on Tuesday, July 19, 2016 - 10:01 am:

If you are not showing the T put in the 14mm adapters and use more modern plugs. That way when you remove the plugs you can leave the adapters in and not further wear out the threads.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 11:56 am:

Thank You

I'm using Autolite plugs because they were the only plugs that "fit" supplied by O'Reillys that day.

I would like to consider the adapters if it won't reduce combustion efficiency by moving the electrode further away from the combustion chamber. Thoughts?


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Menzies on Tuesday, July 19, 2016 - 12:16 pm:

I think the threads are not compatible a different manufactured tap and spark plug die. If a matched set of tap and die were used may improve performance. A non matched pipe thread is difficult to seal and most do leak some. I had one so bad that I used resin on the thread.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Pawelek Brookshire, Texas on Wednesday, July 20, 2016 - 10:01 am:

I use the adapters with Champion RN14YC plugs and they work quite well with my Z head.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Wednesday, July 20, 2016 - 10:31 am:

What size and he range of modern plugs do you recommend? Also, still a .30 gap?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erich Bruckner, Vancouver, WA on Wednesday, July 20, 2016 - 10:47 am:

Do not tighten them down in the aluminum head while it is hot from running as that greatly increases the odds of stripping the threads. My vote is to stay with real model T plugs. Heck, I can send you a set of used good champion X plugs that will work great and Look like they belong. I may be nuts but I think the T will be happiest that way, lol.

There are so many vintage plugs out there that were made for the T. It is fun to run them and the T does seem to like them. I had real good luck with many of the vintage plugs made for the model T.

I use the copper anti-seize paste on the pipe threads and tighten them down by feel. They should not leak, but like Allen said, a little leak is no big deal. I like a .025 gap on the champion X plugs. YMMV

Let me know.


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