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Discussion Starter #1 (Edited)
I searched this forum and found no mention of these plugs that are no longer made. I need an excellent replacement. Size is 14mm. They are OEM for a 1999 PCM 5.8 H.O. (351W with GT-40 heads, 4160 Holley, Prestolite breakerless-distributor). only non-stock ignition item is MSD 6M-2 box. The H.O. engine specs are compression ratio 8.3:1, HP @ 5000rpm= 290, Max rpm 4800-(intermittent); cruise rpm = 4000-4200; real world rpm = 2500-3500, ignition timing 10-degrees BTDC. plug gap .045". Parts person here crossed it to Autolite #763. Is there a better choice than Autolite#763 and why?

Note: I cannot find Autolite#763 either, but Autolite #764 are stated to be a "replacement" for #763....

Thanks for your help/input.
 

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Hey Tex - welcome to the Forums. What you have is very similar to the Lightning truck engine, but your use is sustained higher power. This is why the plug originally specified is colder (AWSF22) than what a Lightning truck would normally use (AWSF32). While the 764 may work, it will likely be a bit hot unless you are a very soft cruiser.

To get the slightly colder heat range (and a 763 is not available anyway), I would suggest the Autolite 103, which is used in GT40 performance applications. Because you have a boat application, I would stick with a standard copper-core plug without any added platinum or iridium, as you will not have them in long enough to benefit from the exotic long-wear metals. Since you can usually find Autolites on sale promotions regularly for cheap, I would replace them each boating season with a fresh set (gap .044) and cruise happy.

NGK and Denso are other brands with high trust (though often faked), but as we have a direct correlation of heat ranges with Autolite (and they are a good plug) I would just stick with them. My 2 cents.

David
 

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Hey Tex - welcome to the Forums. What you have is very similar to the Lightning truck engine, but your use is sustained higher power. This is why the plug originally specified is colder (AWSF22) than what a Lightning truck would normally use (AWSF32). While the 764 may work, it will likely be a bit hot unless you are a very soft cruiser.

To get the slightly colder heat range (and a 763 is not available anyway), I would suggest the Autolite 103, which is used in GT40 performance car parts applications. Because you have a boat application, I would stick with a standard copper-core plug without any added platinum or iridium, as you will not have them in long enough to benefit from the exotic long-wear metals. Since you can usually find Autolites on sale promotions regularly for cheap, I would replace them each boating season with a fresh set (gap .044) and cruise happy.

NGK and Denso are other brands with high trust (though often faked), but as we have a direct correlation of heat ranges with Autolite (and they are a good plug) I would just stick with them. My 2 cents.

David
I have never used these spark plugs personally but I will surely use Autolite to get better results.
 

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I have never used these spark plugs personally but I will surely use Autolite to get better results.
You may have a good brand, but just the wrong specific plug for your specific use.

David
 

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the AWSF plugs have been replaced by the AGSF plugs..not sure if you can get them in 22 range. common would be the AGSF 12 for the cobra and Im sure a 32 range will work just fine for a cast iron gt40 head.. probably similar but better plug would be a NGK tr-6 plug, think its a 4777 number.
 
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