Spark Plug advice

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Model T Ford Forum: Forum 2018: Spark Plug advice
Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Juhl - Michigan's Thumb on Wednesday, October 10, 2018 - 06:06 pm:

I need advice on new spark plugs for my Z-Head T engine when I get it back from the rebuilder. I'm sticking with the 1/2 inch pipe thread type plugs.

I have two Blue Crown TF's that I could probably use but likely will install new plugs on all cylinders.

I see great variation in price from one brand to another but I'm more concerned about performance than price... Any suggestions?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon N.E.Ohio on Wednesday, October 10, 2018 - 06:23 pm:

I use Champion X, Rockauto has them for about $25 each.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon N.E.Ohio on Wednesday, October 10, 2018 - 06:25 pm:

I should note, mine are NOS, not the reproduction ones.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Wednesday, October 10, 2018 - 07:08 pm:

Repo Champion X here. Work great. Never had a problem with them.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Wednesday, October 10, 2018 - 08:28 pm:

What ever plug you get, start at least with a set of NEW not this and that. Motorcraft, Autolite or find a set of NEW vintage plugs. I am not a fan of Champion plugs esp the repo non take apart ones, and for sure not old used ones. There is a reason that plugs get replaced, they do wear out. Cleaning will only get you so far. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Wednesday, October 10, 2018 - 08:59 pm:

I'll agree and disagree with Mark. Some old used plugs are no good and some are just fine. It's also true that some NOS plugs are no good and some are just fine. You can attach wires to the plugs, lay them on top of the engine, and watch them spark. But as John Regan always points out, this is not a real test because it doesn't show you whether they spark under compression. The real test is with a plug tester made for the purpose. You may be lucky enough to find one at a swap meet, or you can make one.

I don't use the new Champion X plugs because they're so ungodly expensive. There are plenty of old ones that work fine, and I pay no more than $5 for them unless they're early ones and very nice. I saw several of the common Champion X plugs for sale today at $5, and I sometimes buy them for $2 or $3.

A modern plug I've used is Autolite 3095. It's the least expensive Model T plug available and works fine, at least for a year or so. My local O'Reilly store doesn't keep it in stock, but can have it here the next day.

Here's a page on those Champions: http://dauntlessgeezer.com/DG95.html


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Coiro on Wednesday, October 10, 2018 - 10:24 pm:

For the sake of appearance and historical correctness, I replaced my Motorcraft F11 plugs, which up to that point had worked just great, with Champion X plugs, which you'd think come from Krypton by the way people talk.

As a result, my engine lost a lot of power and ran rough. -That was surprising.

I shrugged off the mild disappointment, re-installed the Motorcraft F11 plugs and disguised them with the shiny brass thumb-nuts that Lang's sells.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John P. Steele on Wednesday, October 10, 2018 - 10:47 pm:

Tim word of caution. I believe all spark plug threads for T's are going to be 14 or 18mm. Don't use NPT or standard thread taps.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Juhl - Michigan's Thumb on Wednesday, October 10, 2018 - 11:11 pm:

I believe the Z head is 1/2 npt. Same as the original.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon N.E.Ohio on Wednesday, October 10, 2018 - 11:16 pm:

The aftermarket heads are available with 14 mm threads or the stock 1/2" NPT.

I have a brand new set of Autolite and haven't tried them.
So far the Xs have been working fine. If it works, leave it alone.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Reid Central WI on Thursday, October 11, 2018 - 12:05 am:

I use champion 25s which are cheaper then the xs. They seem to hold up ok. The are the 1/2 thread.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Whelihan Danbury, WI on Thursday, October 11, 2018 - 06:09 am:

I have been unable to find vintage Champions at any kind of price at auctions around here, but I did find a set of vintage Varcon plugs. They ran OK for a while. Replaced them with new Champion X plugs and was disappointed with the performance. Tried Champion 25's as well. Not much better that the X variety. Had the best performance out of Motorcraft F11's gapped at .032. Never tried Autolite plugs. The F11's seem to holding up fairly well too. Every spring I rotate the plugs front to back, then move every one up a hole to the front after inspecting them.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe Helena, Montana on Thursday, October 11, 2018 - 11:27 am:

Keep watch for some old gambles dual electrode plugs. They are very good. Firestone are also great. In my experience the new autolite and champions are not as good.


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