[AT] Compression test on 7/8 inch plugs

[szabelski at wildblue.net]

Don’t forget to check that the replacement plug you’re planning on using doesn’t sit deeper in the manifold so that the piston hits it. You may also want to check that having a plug sit higher up in the manifold doesn’t affect the ignition of the fuel in some way. I would think that it doesn’t, but I can’t say for sure. Just a thought.

Also, at one time I did find a chart on the internet that compared plugs from different manufacturers, including heat ranges. Don’t remember where I found it. Try looking for something like “ spark plug heat ranges”. 

Carl


----- Original Message -----
From: Dean VP <deanvp at att.net>
To: 'Antique Tractor Email Discussion Group' <at at lists.antique-tractor.com>
Sent: Wed, 18 Nov 2020 20:09:30 -0500 (EST)
Subject: Re: [AT] Compression test on 7/8 inch plugs

Autolite 3076 is the plug I'm using right now in the 1935 B.  I would like to find something much hotter. The 3076 in the plug number and the 6 is the way Autolite designates heat range of the plug so it is already on the high side.  But since I'm going to have a 7/8" to 14MM adapter there may be a 14 mm plug that is hotter.  I've not found a reference that compares heat ranges between manufacturers

Dean VP
Apache Junction, AZ

-----Original Message-----
From: AT <at-bounces at lists.antique-tractor.com> On Behalf Of Brian VanDragt
Sent: Wednesday, November 18, 2020 1:53 PM
To: Antique Tractor Email Discussion Group <at at lists.antique-tractor.com>
Subject: Re: [AT] Compression test on 7/8 inch plugs

There were 1/2" pipe thread spark plugs (14 threads per inch), but what Dean has is 7/8"-18 straight machine threads, like an Autolite 3076 plug has.

Brian

> On 11/18/2020 3:46 PM Claude Kyker <claudekyker at gmail.com> wrote:
> 
>  
> Dean, if my memory serves me correctly seven eights inch is the same threads that’s on 1/2 inch pipe I assume your plug threads are tapered; pipe threads would be.  If that be the case you can make your own adapter using a half inch pipe. 
> 
> Sent from my iPhone
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