Spark plug gap?

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Model T Ford Forum: Forum 2017: Spark plug gap?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Faulkner on Saturday, August 26, 2017 - 11:28 am:

Anyone have spark plug gap recommendation for champion x plugs? 1917 runabout and mutt depot hack.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Saturday, August 26, 2017 - 11:55 am:

The Bible says 1/32" (.03125"). Some say .025" is better, but I go with the book.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Saturday, August 26, 2017 - 05:23 pm:

Champion Spark Plug suggests .025" gap.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Saturday, August 26, 2017 - 05:30 pm:

Dan Trase picture




Picture saved from Dan T....Thanks !


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Lloid on Saturday, August 26, 2017 - 05:41 pm:

I run repo x plug @ 25 - 30" on all of my Ts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Harper - Keene, NH on Saturday, August 26, 2017 - 07:42 pm:

Hi Chris'

The spark plug manufacturer recommends .025".

The vehicle manufacturer recommends 1/32" (.03125).

Many folks here gap their plugs at .030", or .032", or even up to .035". and are quite satisfied with the results.


Why don't you try all of the above listed settings and find out what works best in YOUR engine as some are happier with one particular gap more than another.

It is a bit like a marriage in that what works in one household (or in this case-under the hood) may not work so well elsewhere. Good luck with your project, Bill


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Saturday, August 26, 2017 - 09:21 pm:

Bill Harper's got the best idea, try different gaps between .025 and .035 and see where yours runs best. Me it's .032-.035
Condition of coils and whether running on battery or magneto may affect the gap you use.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Pawelek Brookshire, Texas on Saturday, August 26, 2017 - 09:34 pm:

And the fellows do not mean try a different gap on all four cylinders at the same time! :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Saturday, August 26, 2017 - 09:54 pm:

LOL I was thinking about someone doing that as I posted! :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Faulkner on Saturday, August 26, 2017 - 10:22 pm:

Thank you all very much.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erich Bruckner, Lake Oswego, OR on Sunday, August 27, 2017 - 12:04 pm:

I would be interested in hearing the results if anyone does do the gap performance comparison test. Should be some relatively easy scientific method combined with seat of the pants measurements? Or perhaps some out there could do some more refined measurements????

Selfishly, I am most interested in such a test being performed with the stock Ford coil setup instead of modernised "improvements".


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Sunday, August 27, 2017 - 01:38 pm:

I wonder if perhaps the fact that the early T's had a higher compression head would have then used the .025 gap which is electrically about the same gap as .03125 with the later and slightly lower compression head. Just my musing here - not stating a fact in evidence or proof of anything.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Smith, Lomita, California on Sunday, August 27, 2017 - 05:05 pm:

Years ago, I read somewhere one thin dime!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Sunday, August 27, 2017 - 08:16 pm:

The reproduction Champion X wrapper says it all..... and recommended by their engineers for a gap of .025".

Why don't we use this as a fact and gap accordingly ??????

Try it, your engine will like it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Sunday, August 27, 2017 - 08:19 pm:

Our 1950 Buick Special, with a 6 volt system, used a spark plug gap of .025".

Used .025" gap on our '26 Runabout, started easier on battery and magneto, and had seat of the pants pep at speed to boot !


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Monday, August 28, 2017 - 07:41 pm:

Chris Falkner.... was this helpful ???


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Monday, August 28, 2017 - 08:13 pm:

I laughed out loud at the notion that something is "recommended by our engineers"!

I also know that in the 1950's, 4 out of 5 physicians preferred Camels!

Folks, gap 'em like you want to...different cars thrive on different gaps...it's highly unlikely that any engineer had any input to that little piece of advertising wrapped around the spark plug.

Engineers design stuff. Ad men sell it...and sell it by any means necessary. The LARGE font is especially impressive and carries more weight than regular font. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Tuesday, August 29, 2017 - 07:42 am:

Scott: Believe what you want, .025" gap works for me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Tuesday, August 29, 2017 - 10:10 am:

What I believe is that most "T"s with healthy coils will run just fine on pretty much anything between .025 and .031", with a few "T"s being a bit particular one way or another.

As a retired aerospace systems engineer, what I know is that a large company, particularly a publicly held company, will sell, run, fly or say pretty much whatever management decides will be most profitable and not necessarily what the engineers recommend.

Not trying to pick fights or be smart about it. It just is what it is.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Tuesday, August 29, 2017 - 10:49 am:

Very aware of the ways of the business world, didn't fall off the turnip truck yesterday.....

Scott: Believe what you want, .025" gap works for me.

Bob J.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Manuel, Lafayette, La. on Tuesday, August 29, 2017 - 11:50 am:

Chris, I suggest you get some of those plugs with two benders; set one at twenty five and one at thirty. Mark the thirty gap side of your plugs and install them toward the front and preferably with the car parked toward magnetic north if you plan on running on mag. That's the best way. Trust me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Manuel, Lafayette, La. on Tuesday, August 29, 2017 - 11:54 am:

Sorry, Chris, I just reviewed your original post and now realize one of your vehicles is a depot hack. Better to go perpendicular to the camshaft on that one.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Tuesday, August 29, 2017 - 12:00 pm:

I don't think it is a coincidence engines with Champions set up with 0.025" gap, concentric CAM shaft / timer alignment and coils set up for the same dwell time to fire consistently run exceptionally well.

In my opinion, stuff Engineers design well tends to sell themselves. Problems often arise when users fail to follow directions. Yes, other random combinations of the same variables involved MAY achieve acceptable results but doing so on a consistent basis typically proves to be elusive. Sound familiar? When all else fails, follow the directions. :-)

(Message edited by mkossor on August 29, 2017)


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Manuel, Lafayette, La. on Tuesday, August 29, 2017 - 12:33 pm:

I run Champion X plugs set at 25. My feeble attempt at humor was an effort to change the tone of the thread which I felt was getting a little prickly. As they too often do.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Tuesday, August 29, 2017 - 03:29 pm:

Damn right John !! And with good reason. Ain't nobody gonna tell ME to read directions !! Why, readin' a manual is just like cheatin' !!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Vern (Vieux Carre) on Tuesday, August 29, 2017 - 03:36 pm:

Happy 1 year forum anniversary Rich.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham on Tuesday, August 29, 2017 - 08:41 pm:

Wow !! A year already ?! ? Thanks, Vern !! It's been a very happy year, I love this place ! (and It only took me eight weeks to go from " just reading" to driving a T again)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Shirley on Tuesday, August 29, 2017 - 09:01 pm:

I,was always told, the gap should be the thickness of a thin dime.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ed Baudoux Grayling Michigan on Tuesday, August 29, 2017 - 09:43 pm:

I mean no disrespect to anyone on this forum, but I'd like to add that Champion Spark Plug sent Dad to Toledo back in the 1970's, for a technical seminar. It made a big impression on me, as Dad's shop was a one-man operation, and had been in business for 30 years at the time. They few dozens of sets of plugs he bought per year, surely did not warrant such extravagances. They flew him from Saginaw to Toledo and back on their jet. He told me about the great lengths the engineers went to, to design plugs. Remember the AMC 258 in-line six? Champion designed a special plug for them, with an extra long porcelain and center electrode. It improved driveability, horsepower, torque, and fuel mileage drastically. I thought it was space-age technology, when he told me about engineers reading the spark plug temperature of a motorcycle racing around the test track, through wireless communication. I'd follow the directions of the Champion engineers. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Noonan - Norton, MA. on Tuesday, August 29, 2017 - 11:56 pm:

I personally wouldn't trust any gap setting as Gospel, just because its written on fancy paper. Just think about all the the different setups we use in the T community. Different heads, carbs, intakes, ignition systems etc. I installed them straight out of the box at .025, and my T ran like crap, opened them up to .030 and it ran beautifully. Definitely experiment with different settings to see what your T likes the best, you won't be disappointed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Wednesday, August 30, 2017 - 07:42 pm:

Thank you Ed B. for sharing your father's learning experience.... learn something every day.


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