For those who do, how do you gap spark plugs? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**dmjlambert** · 02-25-2024, 06:25 PM

So back in the day I used the slotted bender built into the gap gauge to bend the electrode. But I have found on modern spark plugs the electrode is very hard and the slotted bender bends before the electrode and there is often not enough room to fit the slot of the bender in there to do the bend. On the last batch I clamped the electrode with vise grips and bent it, but it didn't feel very scientific to be doing that. What is the correct way? I know a lot of people just leave them gapped at whatever gap they are at when purchased, but sometimes I want do dial in my own preferred value. Considering how seldom I do this I'm not sure I would get some $100 tool for it, but perhaps I could.

**'68OrangeSunshine** · 02-25-2024, 06:34 PM

Gee, I'm still using the included gapper hook on the feeler gauge. But then I insist on copper electrode plugs. No fancy-dancy platinum for me -- you can't clean it up with an ignition file. Also I'm only going to .045. Both trucks have HEI.

The old Craftsman key chain round gauge, with an inclined plane on the circumference edge might help you if you have a way to drive it between the tip and the ''claw.''

If I were a Pro, and worked in a shop, I could write off the expense of the $100 tool and impress customers with my mojo by using it. But otherwise, no thanks.

**Steeveedee** · 02-25-2024, 08:27 PM

I was a pro and worked in a shop and used the tapered tool, and the one with bits of wire on it. Electrodes weren't that tough, back in the day.

**Rust_never_sleeps** · 02-25-2024, 09:59 PM

I could never find the damned tool, I always used whatever pliers I found first

Sicklajoie · 02-25-2024, 10:29 PM

What the heck type of plugs are you using?

**dmjlambert** · 02-25-2024, 11:19 PM

Autolite 24 copper resistor plug.

**70STOVEBOLT** · 02-26-2024, 07:58 AM

I use the round gauge like 68OrangeSunshine described.

**Palf70Step** · 02-26-2024, 08:33 AM

I have alll three os these in my tool box, but tend to grad the flat blade one and it's tool as that is what I am use to using.

MARKDTN · 02-26-2024, 11:37 AM

I have one each of these.

weq92f · 02-26-2024, 03:33 PM

.

I like how Derek of Vice Grip Garage does it...

He looks at the new plug and says "gapped."

-klb

**'68OrangeSunshine** · 02-26-2024, 03:44 PM

Quote:

Originally Posted by Palf70Step

I have alll three os these in my tool box, but tend to grad the flat blade one and it's tool as that is what I am use to using.

I have those too. The top type is what I use most, but I also have a later one for HEI, with .045 as the smaller setting.
It also has a thicker, beefier bending hook.

**71CHEVYSHORTBED402** · 02-27-2024, 03:15 PM

Quote:

Originally Posted by Palf70Step

I have alll three os these in my tool box, but tend to grad the flat blade one and it's tool as that is what I am use to using.

I have those too. Pick what works at the time.

bnorth · 02-27-2024, 06:11 PM

I find on newer plugs I am always closing up the gap a bit. Don't remember the last time I opened them. I use the round tapered gauge and just give a couple raps of the electrode on my vice to close them up.

**dmjlambert** · 02-27-2024, 08:30 PM

Do you insert the gauge at the setting you want while rapping it on the vice, or rap/measure/repeat?

**dmb** · 02-27-2024, 08:40 PM

The old knife blade aint bad for opening them up. Also good for cleaning finger nails, cutting wire and getting viennia sausage out the can lol

**'68OrangeSunshine** · 02-28-2024, 01:12 AM

Quote:

Originally Posted by dmb

The old knife blade aint bad for opening them up. Also good for cleaning finger nails, cutting wire and getting viennia sausage out the can lol

That last option is the most important.

**'68OrangeSunshine** · 02-28-2024, 01:16 AM

Quote:

Originally Posted by dmjlambert

Do you insert the gauge at the setting you want while rapping it on the vice, or rap/measure/repeat?

If the gap's too close, I bend the thingie back with the hook, then measure. If now too wide, I give it a smack with a 3/8 Ratchet handle. My old Craftsman has a rectangular cross section handle. Figure 1/1000th per casual whack.
Measure again til it's there..
The important thing is not to spill the beer.

bnorth · 02-28-2024, 08:32 PM

Quote:

Originally Posted by dmjlambert

Do you insert the gauge at the setting you want while rapping it on the vice, or rap/measure/repeat?

rap/measure/repeat

**dmjlambert** · 02-28-2024, 11:42 PM

Thanks for the education, I'll fix up these spark plugs just right.

02-25-2024, 06:25 PM	#1
dmjlambert Senior Member Join Date: Apr 2016 Location: Cypress, TX Posts: 3,816	For those who do, how do you gap spark plugs? So back in the day I used the slotted bender built into the gap gauge to bend the electrode. But I have found on modern spark plugs the electrode is very hard and the slotted bender bends before the electrode and there is often not enough room to fit the slot of the bender in there to do the bend. On the last batch I clamped the electrode with vise grips and bent it, but it didn't feel very scientific to be doing that. What is the correct way? I know a lot of people just leave them gapped at whatever gap they are at when purchased, but sometimes I want do dial in my own preferred value. Considering how seldom I do this I'm not sure I would get some $100 tool for it, but perhaps I could.

02-25-2024, 06:34 PM	#2
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,456	Re: For those who do, how do you gap spark plugs? Gee, I'm still using the included gapper hook on the feeler gauge. But then I insist on copper electrode plugs. No fancy-dancy platinum for me -- you can't clean it up with an ignition file. Also I'm only going to .045. Both trucks have HEI. The old Craftsman key chain round gauge, with an inclined plane on the circumference edge might help you if you have a way to drive it between the tip and the ''claw.'' If I were a Pro, and worked in a shop, I could write off the expense of the $100 tool and impress customers with my mojo by using it. But otherwise, no thanks. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

02-25-2024, 08:27 PM	#3
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,618	Re: For those who do, how do you gap spark plugs? I was a pro and worked in a shop and used the tapered tool, and the one with bits of wire on it. Electrodes weren't that tough, back in the day. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

02-25-2024, 09:59 PM	#4
Rust_never_sleeps Senior Member Join Date: Jun 2022 Location: San Ramon,CA Posts: 569	Re: For those who do, how do you gap spark plugs? I could never find the damned tool, I always used whatever pliers I found first __________________ 1970 C10 Custom longbed 350/350

02-25-2024, 10:29 PM	#5
Sicklajoie The Niner Join Date: Nov 2010 Location: Broad Brook, CT Posts: 2,498	Re: For those who do, how do you gap spark plugs? What the heck type of plugs are you using? Attached Images __________________ "A good racer is one whose head is in communication with his balls." - Richie Evans 1970 C/20 - 402/TH400/3.54s - 74K miles 2003 GMC Sierra 2500 - Wheatland Yellow Niner Progression Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=697183 Classic Trucks article: https://www.motortrend.com/features/...et-c20-driven/

02-25-2024, 11:19 PM	#6
dmjlambert Senior Member Join Date: Apr 2016 Location: Cypress, TX Posts: 3,816	Re: For those who do, how do you gap spark plugs? Autolite 24 copper resistor plug.

02-26-2024, 07:58 AM	#7
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,369	Re: For those who do, how do you gap spark plugs? I use the round gauge like 68OrangeSunshine described. __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Sliding Rear Window Power Windows Power Locks Sniper EFI 2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear

02-26-2024, 08:33 AM	#8
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 47,091	Re: For those who do, how do you gap spark plugs? I have alll three os these in my tool box, but tend to grad the flat blade one and it's tool as that is what I am use to using. Attached Images __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

02-26-2024, 11:37 AM	#9
MARKDTN Registered User Join Date: Jan 2011 Location: Chattanooga, TN Posts: 2,160	Re: For those who do, how do you gap spark plugs? I have one each of these. Attached Images __________________ '83 K20-TPI '73 C10 '79 C10-ex-diesel(SOLD) '07 Tahoe(Son driving) '14 Suburban-DD '71 C10-current project

02-26-2024, 03:33 PM	#10
weq92f Registered User Join Date: Oct 2016 Location: Dallas Texas Posts: 3,165	Re: For those who do, how do you gap spark plugs? . I like how Derek of Vice Grip Garage does it... He looks at the new plug and says "gapped." -klb __________________ 67 C10 fleet fuel injected '70 402, 700r4, 3.73 posi 07 335 sport turbo 6sp 94 Trans Am GT LT1 6sp posi -- sold after 22yrs 99 540 sport V8 6sp -- sold 73 240z L24 4sp -- given to friend 68 C10 step 350/350 3.73 open -- sold

02-27-2024, 06:11 PM	#13
bnorth Registered User Join Date: Aug 2020 Location: Salmon Arm BC Posts: 199	Re: For those who do, how do you gap spark plugs? I find on newer plugs I am always closing up the gap a bit. Don't remember the last time I opened them. I use the round tapered gauge and just give a couple raps of the electrode on my vice to close them up. __________________ 1970 C10 l/b 292/4spd Build: http://67-72chevytrucks.com/vboard/s...d.php?t=811062

02-27-2024, 08:30 PM	#14
dmjlambert Senior Member Join Date: Apr 2016 Location: Cypress, TX Posts: 3,816	Re: For those who do, how do you gap spark plugs? Do you insert the gauge at the setting you want while rapping it on the vice, or rap/measure/repeat?

02-27-2024, 08:40 PM	#15
dmb Active Member Join Date: Sep 2023 Location: randolph va Posts: 151	Re: For those who do, how do you gap spark plugs? The old knife blade aint bad for opening them up. Also good for cleaning finger nails, cutting wire and getting viennia sausage out the can lol

02-28-2024, 11:42 PM	#19
dmjlambert Senior Member Join Date: Apr 2016 Location: Cypress, TX Posts: 3,816	Re: For those who do, how do you gap spark plugs? Thanks for the education, I'll fix up these spark plugs just right.



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