Another Spark Plug Question
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From: Southern Virginia
Another Spark Plug Question
While checking the compression on a 69 400 engine, I noticed the spark plug tips were white, the engine has R 44 S plugs in it, should we go to a colder plug? Thanks.
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From: Rogues Island, USA
The 360hp version calls for a R43S but all others, 325hp and 350hp call for the R44S.
http://www.tpocr.com/olds1.html
http://www.tpocr.com/olds1.html
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From: Rogues Island, USA
Last edited by TripDeuces; Aug 8, 2016 at 08:45 PM.
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From: Poteau, Ok
Your engine could be running on the lean side.
Here is a simple chart
http://4.bp.blogspot.com/-j0zzs4Ml8N...ug+Reading.jpg
Here is a simple chart
http://4.bp.blogspot.com/-j0zzs4Ml8N...ug+Reading.jpg
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Joined: Sep 2013
Posts: 3,645
Are you seeing white or gray. Years ago grayish was okay when using premium gas Ethel was king leaded gas. On today's gas white is lean. 87, 89,91 octane Race gas should have a geenish gold color. JMO
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Joined: Sep 2013
Posts: 3,645
Your engine could be running on the lean side.
Here is a simple chart
http://4.bp.blogspot.com/-j0zzs4Ml8N...ug+Reading.jpg
Here is a simple chart
http://4.bp.blogspot.com/-j0zzs4Ml8N...ug+Reading.jpg
Registered User
Joined: Sep 2013
Posts: 3,645
Registered User
Joined: Nov 2008
Posts: 8,477
From: Central Fl
Good chart but that's only half the story boys.
Look at the ground strap. You should see a grayish color from the tip towards the side no more than halfway back. More than that and it's a plug that's too hot. If the grey stops right behind the tip it's too cold.
Also if the porcelain is white, yet the metal part of the plug outside of that is black, then plug could still be too cold.
General rule of thumb, on today's lower octane fuels you'll want the coldest plug you can without fouling. That, along with the right air/fuel should give you the best performance.
Hope this helps.
Look at the ground strap. You should see a grayish color from the tip towards the side no more than halfway back. More than that and it's a plug that's too hot. If the grey stops right behind the tip it's too cold.
Also if the porcelain is white, yet the metal part of the plug outside of that is black, then plug could still be too cold.
General rule of thumb, on today's lower octane fuels you'll want the coldest plug you can without fouling. That, along with the right air/fuel should give you the best performance.
Hope this helps.
Last edited by cutlassefi; Aug 7, 2016 at 07:27 AM.
72 Olds CS
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