Spark plug bigger gap
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Fleet Mechanic
Joined: Feb 2003
Posts: 1,314
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Spark plug bigger gap
I just realized that I may have gapped the spark plugs for my F250 larger than the specs. I tuned it up this summer and since then, it has run well. Problem was, the specs said something like 0.044" but when I used a round device with different gaps, I pushed it all the way in, resulting in 0.055", about 0.010" bigger.
Is that really bad? Should I take them out and regap them? I want to check one first and see its gap.
Reason I found out, I was installing the plugs on another vehicle and realized I was gapping them wrong when I realized that when I pushed the round disk all the way in, it increased the gap by 0.010".
The engine is 460 (EFI) and the plugs are Autolite.
Is that really bad? Should I take them out and regap them? I want to check one first and see its gap.
Reason I found out, I was installing the plugs on another vehicle and realized I was gapping them wrong when I realized that when I pushed the round disk all the way in, it increased the gap by 0.010".
The engine is 460 (EFI) and the plugs are Autolite.
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Fleet Mechanic
Joined: Feb 2003
Posts: 1,314
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Yes, I am talking about the round metal gauge which has numbers around the perimeter all the way across. It typically sells at auto parts places for 99 cents.
I think I used it incorrectly. Instead of sticking it between the two metal surfaces of the spark plug, about 2 mm or so, I found 0.044 spot and pushed it in maybe 5-7mm. The thickness seems to vary from the edge towards the center even if you remain with the same 0.044 spot.
Sorry for being so tedious, but you know, the devil is in the details.
I am going to pull one plug and see if it is indeed 0.044 like it should be. I should do it anyway to examine it.
Really, the plugs were easy on that engine, except for one.
I think I used it incorrectly. Instead of sticking it between the two metal surfaces of the spark plug, about 2 mm or so, I found 0.044 spot and pushed it in maybe 5-7mm. The thickness seems to vary from the edge towards the center even if you remain with the same 0.044 spot.
Sorry for being so tedious, but you know, the devil is in the details.
I am going to pull one plug and see if it is indeed 0.044 like it should be. I should do it anyway to examine it.
Really, the plugs were easy on that engine, except for one.
New User
Joined: Jan 2008
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Considering the center electrode erode's, I set mine on the less side of .044" allowing it to get more space through use.
I alwys slide the ground electrode in at the narrow edge and measure by slowly moving it around.
I alwys slide the ground electrode in at the narrow edge and measure by slowly moving it around.
Post Fiend
Joined: Jan 2003
Posts: 10,323
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From: Montana Territory
Yeah, like fordeverpower said, it can increase power but only if you run a higher output coil and low resistance wires. If you have a CD buzz box, then you can run the bigger gap as well, because some of them send out 12 sparks for every normal one, so you are gonna get complete burn.
Post Fiend
Joined: Feb 2003
Posts: 6,940
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From: Eastern WA
It's harder to fire a cold plug than a hot one so you may experience harder starting and possibly rough running/driveability issues, especially when cold. IMHO, investigate and set to factory specs on a stock engine. After all, if a wider gap resulted in a benefit, I'm sure the manufacturer would have loved to deliver that benefit to the customers when it was new.
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Postmaster
Joined: Jan 2003
Posts: 4,417
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From: Durham, NC
I agree with Cowboy, the plugs should be set to spec. The increase gap means a higher voltage is required, which will but
more stress on plug wires, etc. ....If a wider gap was better, then
an engine would run better on worn out plugs!!!!
more stress on plug wires, etc. ....If a wider gap was better, then
an engine would run better on worn out plugs!!!!
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Logistics Pro
Joined: Jan 2002
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From: suburban atlanta
Bigger is not always better... Take 'em out, and set the gap correctly. You may get a little better burn with a larger gap, with attendant stress to the components, but you run the risk of a misfire when you push the limit. The guys have it right. Why suggest .044-.046 when bigger would be better? Because it has enough 'spark' to get the mix fired AND it fires reliably. It will most likely run smoother with the correct gap.
My 2 cents. Change please...
tom
My 2 cents. Change please...
tom
Post Fiend
Joined: Jun 2003
Posts: 5,643
Likes: 8
From: NE Texas
Carp,
If you slid the plugs in at the .044” setting, then pushed it all the way from the lip to the inner shoulder of the gauge it should still be .044”.
Unless I’m not understanding the gauge settings right. It should only change thickness the further up/down the scale you go, not in or out. Of course you could have a bad gauge and it would vary.
If you slid the plugs in at the .044” setting, then pushed it all the way from the lip to the inner shoulder of the gauge it should still be .044”.
Unless I’m not understanding the gauge settings right. It should only change thickness the further up/down the scale you go, not in or out. Of course you could have a bad gauge and it would vary.
Thread Starter
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Fleet Mechanic
Joined: Feb 2003
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If you slid the plugs in at the .044” setting, then pushed it all the way from the lip to the inner shoulder of the gauge it should still be .044”.
That's what I thought but I just tuned up my Topaz, doing just that and found out that gap was really 0.055, not 0.045. Had to remove the plugs and regap them.
That makes sense. I am definitely going to pull one of them out and investigate. Luckily, they are easy to swap, all but maybe the rear driver's side plug. (Took me 40 mins to find the right extensions, but once I did, it was easy).
Maybe I should also replace my spark plug gapping tool, I think it is wrong.
That's what I thought but I just tuned up my Topaz, doing just that and found out that gap was really 0.055, not 0.045. Had to remove the plugs and regap them.
That makes sense. I am definitely going to pull one of them out and investigate. Luckily, they are easy to swap, all but maybe the rear driver's side plug. (Took me 40 mins to find the right extensions, but once I did, it was easy).
Maybe I should also replace my spark plug gapping tool, I think it is wrong.
Last edited by carpe_diem; Feb 19, 2004 at 09:12 AM.
Postmaster
Joined: Jan 2003
Posts: 4,417
Likes: 3
From: Durham, NC
Originally posted by carpe_diem
That makes sense. I am definitely going to pull one of them out and investigate. Luckily, they are easy to swap, all but maybe the rear driver's side plug. (Took me 40 mins to find the right extensions, but once I did, it was easy).
Maybe I should also replace my spark plug gapping tool, I think it is wrong.
That makes sense. I am definitely going to pull one of them out and investigate. Luckily, they are easy to swap, all but maybe the rear driver's side plug. (Took me 40 mins to find the right extensions, but once I did, it was easy).
Maybe I should also replace my spark plug gapping tool, I think it is wrong.
platinum plugs, be careful not to damage the platinum "beads".
Postmaster
Joined: Jan 2003
Posts: 4,417
Likes: 3
From: Durham, NC
Originally posted by superrangerman2002
Some are, some aren't.
Some are, some aren't.
gapping tool on platinum plugs, you CANNOT use the circular
gapping tool!!!