69 L46 spark plug
Thread Starter
Drifting
Joined: May 2011
Posts: 1,536
Likes: 1
From: Boca Raton FL
69 L46 spark plug
I read a previous thread where people were talking about using AC R45S plugs for an L46. Think the specs were originally AC R44S. Going to change plugs this week and wanted to hear some thoughts. Also gap .035"? Thanks
http://www.69corvette.com/69specs.html
http://www.69corvette.com/69specs.html
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
The newer catalogues will show a R43 as the correct plug not the 44 because the '44 is obslele....this is not correct...also its not the end of the world....the best alternstive is a 45 as a good all around plug and yes, a gap of .035
Race Director
Joined: Jul 2001
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45s are a good choice for street use.
Burning Brakes
Joined: Oct 2006
Posts: 1,089
Likes: 43
From: Native Californian CALIFORNIA
Army
Use R45
The AC R-44 spark plug, also known as GM #5569993, was discontinued in April of 1990 and replaced by the R-43. So, the R-44 has been gone for a long time.
In the AC system "R" means the plug is the RFI resistor type; "4" means it's a 14 mm thread, and "5" is the heat range - suffixes as previously noted, which decode to other plug geometry features. Some manufacturers also use prefixes to the numerical heat range to denote geometric features. The higher the heat range number, the "hotter" the plug meaning that it runs hotter for a given load than lower number heat ranges. Most other manufacturers follow this convention, except Denso, where a higher number is colder.
For normal street and highway driving AC heat range "5" works best in all SBs, regardless of horsepower rating. It's driving conditions that determine plug heat range, not engine horsepower.
Heat range "5" AC plugs usually are the best selection for normal road operation, regardless of HP rating. Engines with TI or HEI ignitions can tolerate a lower heat range since they have double the per spark ignition energy of the point type systems so they will tolerate considerable fouling before misfire occurs
The AC R-44 spark plug, also known as GM #5569993, was discontinued in April of 1990 and replaced by the R-43. So, the R-44 has been gone for a long time.
In the AC system "R" means the plug is the RFI resistor type; "4" means it's a 14 mm thread, and "5" is the heat range - suffixes as previously noted, which decode to other plug geometry features. Some manufacturers also use prefixes to the numerical heat range to denote geometric features. The higher the heat range number, the "hotter" the plug meaning that it runs hotter for a given load than lower number heat ranges. Most other manufacturers follow this convention, except Denso, where a higher number is colder.
For normal street and highway driving AC heat range "5" works best in all SBs, regardless of horsepower rating. It's driving conditions that determine plug heat range, not engine horsepower.
Heat range "5" AC plugs usually are the best selection for normal road operation, regardless of HP rating. Engines with TI or HEI ignitions can tolerate a lower heat range since they have double the per spark ignition energy of the point type systems so they will tolerate considerable fouling before misfire occurs
Thread Starter
Drifting
Joined: May 2011
Posts: 1,536
Likes: 1
From: Boca Raton FL
Use R45
The AC R-44 spark plug, also known as GM #5569993, was discontinued in April of 1990 and replaced by the R-43. So, the R-44 has been gone for a long time.
In the AC system "R" means the plug is the RFI resistor type; "4" means it's a 14 mm thread, and "5" is the heat range - suffixes as previously noted, which decode to other plug geometry features. Some manufacturers also use prefixes to the numerical heat range to denote geometric features. The higher the heat range number, the "hotter" the plug meaning that it runs hotter for a given load than lower number heat ranges. Most other manufacturers follow this convention, except Denso, where a higher number is colder.
For normal street and highway driving AC heat range "5" works best in all SBs, regardless of horsepower rating. It's driving conditions that determine plug heat range, not engine horsepower.
Heat range "5" AC plugs usually are the best selection for normal road operation, regardless of HP rating. Engines with TI or HEI ignitions can tolerate a lower heat range since they have double the per spark ignition energy of the point type systems so they will tolerate considerable fouling before misfire occurs
The AC R-44 spark plug, also known as GM #5569993, was discontinued in April of 1990 and replaced by the R-43. So, the R-44 has been gone for a long time.
In the AC system "R" means the plug is the RFI resistor type; "4" means it's a 14 mm thread, and "5" is the heat range - suffixes as previously noted, which decode to other plug geometry features. Some manufacturers also use prefixes to the numerical heat range to denote geometric features. The higher the heat range number, the "hotter" the plug meaning that it runs hotter for a given load than lower number heat ranges. Most other manufacturers follow this convention, except Denso, where a higher number is colder.
For normal street and highway driving AC heat range "5" works best in all SBs, regardless of horsepower rating. It's driving conditions that determine plug heat range, not engine horsepower.
Heat range "5" AC plugs usually are the best selection for normal road operation, regardless of HP rating. Engines with TI or HEI ignitions can tolerate a lower heat range since they have double the per spark ignition energy of the point type systems so they will tolerate considerable fouling before misfire occurs
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
If your ignition is stock points, then .035" gap is fine. If you have changed over to an electronic ignition, set gap according to specs for that ignition system (this assumes that you have a coil which is recommended by the ignition mfg). The coil really determines the spark potential; the gap can be wider, if the spark potential is high enough to 'jump' it. But, .035" will work OK with any system.
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Drifting
Joined: Sep 1999
Posts: 1,970
Likes: 91
I read a previous thread where people were talking about using AC R45S plugs for an L46. Think the specs were originally AC R44S. Going to change plugs this week and wanted to hear some thoughts. Also gap .035"? Thanks
http://www.69corvette.com/69specs.html
http://www.69corvette.com/69specs.html
!970 11-1 msd ignition. Think 40 or 45 on the gap.
Thread Starter
Drifting
Joined: May 2011
Posts: 1,536
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From: Boca Raton FL
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
I'm digging this up because at the autoparts store their system tells them the correct plug for a '69 L46 is an R43S. I balked at purchasing them, but has anyone else run R43S?
For my application, I would think this would be too cool of a plug. I run pretty rich, and typically just cruising.
For my application, I would think this would be too cool of a plug. I run pretty rich, and typically just cruising.
Instructor
Joined: Mar 2011
Posts: 176
Likes: 9
From: Uttendorf - Austria
I'm digging this up because at the autoparts store their system tells them the correct plug for a '69 L46 is an R43S. I balked at purchasing them, but has anyone else run R43S?
For my application, I would think this would be too cool of a plug. I run pretty rich, and typically just cruising.
For my application, I would think this would be too cool of a plug. I run pretty rich, and typically just cruising.
Last weekend I checked my spark plugs to order some to be prepared to change them. Built in is still R43S, normally darker than on pic. But at last drive before checking them I had some fun so they are a little more grey now. Pic makes it a little more white but its grey so no problem
For the moment I just adjusted them to 0,9mm and now I am looking for new ones - R43S isnt available so I will look for R44S or R45S - what would you think would be better ?
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Race Director
Joined: Jul 2001
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Instructor
Joined: Mar 2011
Posts: 176
Likes: 9
From: Uttendorf - Austria
I contacted AC Delco, they seem to have a dealer in UK, maybe they can send some ....
Napa / Autozone isnt existing here in Europe, european Amazon doesnt have it also
So, if R43S and R45S would be available what is the advantage of the 45s especially when R43S was the original one ?
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
I thought to have read that above - as English isnt my mothers language and I live in Austria please excuse me.
I contacted AC Delco, they seem to have a dealer in UK, maybe they can send some ....
Napa / Autozone isnt existing here in Europe, european Amazon doesnt have it also
So, if R43S and R45S would be available what is the advantage of the 45s especially when R43S was the original one ?
I contacted AC Delco, they seem to have a dealer in UK, maybe they can send some ....
Napa / Autozone isnt existing here in Europe, european Amazon doesnt have it also
So, if R43S and R45S would be available what is the advantage of the 45s especially when R43S was the original one ?
Instructor
Joined: Mar 2011
Posts: 176
Likes: 9
From: Uttendorf - Austria
