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Old 04-26-2021, 10:54 AM   #1
JayJay
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Default Torque spec for spark plugs?

I am likely being waaaay too anal, but is there a torque spec for the spark plugs on the original head? In the back of my mind I recall seeing one but can't find it in any of the references I have on hand.

Otherwise, snug plus a scoch will have to do.

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Old 04-26-2021, 11:15 AM   #2
Kurt in NJ
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Default Re: Torque spec for spark plugs?

Use original wrench,as tight as you can get with one hand
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Old 04-26-2021, 11:46 AM   #3
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Default Re: Torque spec for spark plugs?

Otherwise, snug plus a scoch will have to do.


I like such workable technical terms !
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Old 04-26-2021, 04:56 PM   #4
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Default Re: Torque spec for spark plugs?

Seems like I recall seeing....and using......one for about 15 ft/lb recently.
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Old 04-26-2021, 06:03 PM   #5
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Default Re: Torque spec for spark plugs?

Quote:
Originally Posted by fried okra View Post
Seems like I recall seeing....and using......one for about 15 ft/lb recently.
I think an original wrench, tightening by hand, would be more than 15ft/#, especially back in the day when men were stronger, and didn't want a plug shoot through the hood out in nowhere land!

Last edited by J Franklin; 04-26-2021 at 08:19 PM. Reason: punctuation!?
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Old 04-26-2021, 06:43 PM   #6
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Default Re: Torque spec for spark plugs?

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Waaay to anal ! Just like you said.
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Old 04-26-2021, 07:36 PM   #7
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Default Re: Torque spec for spark plugs?

I had just posted this to a thread about manifold torque... same applies here.

"good and tight" is about right !! I suspect that about 99.9% of all Model A's lived their first 50 -60 years without ever encountering a torque wrench.

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Old 04-27-2021, 12:54 AM   #8
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Default Re: Torque spec for spark plugs?

The length of the original wrench would get you more like 45-50 FPs if you pulled them real tight. They don't need to be that tight. Just snugged down so they don't leak past the sealing washers.
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Old 04-27-2021, 10:37 AM   #9
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Default Re: Torque spec for spark plugs?

Thanks, all. I've spent a lot of time working on BMW motorcycles where engine and tranny parts are either aluminum or magnesium, and torqueing to spec is pretty critical. I'm as interested in consistency as I am in the value. I'll mess around and see what feels right and develop a spec from that, I suspect it's going to be in the 20-25 ft-lb range (about half of the head nut spec of 55 ft-lb).

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Old 04-27-2021, 11:25 AM   #10
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Default Re: Torque spec for spark plugs?

Quote:
Originally Posted by redmodelt View Post
The length of the original wrench would get you more like 45-50 FPs if you pulled them real tight. They don't need to be that tight. Just snugged down so they don't leak past the sealing washers.
I'm with you this. Go beyond that and you will have a problem getting them loose, especially on aluminum heads.
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Old 04-27-2021, 12:35 PM   #11
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Default Re: Torque spec for spark plugs?

A little anti seize on the threads will help with consistent tightening and help when it comes time to remove the plugs, especially with aluminum heads.
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Old 04-27-2021, 04:39 PM   #12
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Default Re: Torque spec for spark plugs?

Head types that is: C. I. vs Aluminum and thread size matters see tables here.

Following info is from this URL:

https://ricksfreeautorepairadvice.co...k-plug-torque/

Last edited by Benson; 04-27-2021 at 04:46 PM.
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Old 04-27-2021, 04:51 PM   #13
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Default Re: Torque spec for spark plugs?

Quote:
Originally Posted by Benson View Post
Head types that is: C. I. vs Aluminum and thread size matters see tables here.

Following info is from this URL:

https://ricksfreeautorepairadvice.co...k-plug-torque/
This is interesting. So for a 7/8" thread and cast iron head (Model A), this table recommends 50-55 ft-lb, or around the same as the head nuts. That just seems high to me.

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Old 04-27-2021, 07:49 PM   #14
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Default Re: Torque spec for spark plugs?

Quote:
Originally Posted by JayJay View Post
I am likely being waaaay too anal, but is there a torque spec for the spark plugs on the original head? In the back of my mind I recall seeing one but can't find it in any of the references I have on hand.

Otherwise, snug plus a scoch will have to do.

JayJay

Tight is tight too tight is broke??


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