Spark Plug Gap

[Joe Flanagan]

What's the accepted standard for spark plug gap on a flathead? My manual says it should be .028 for a standard plug and .035 for a "resistor" type plug, whatever that is. I thought I read on this forum that it should be .025. 

[P15-D24]

http://p15-d24.com/page/p15d24/reference/maintenance.html

[Joe Flanagan]

Thanks very much. But what is a "resistor plug?"

[Barabbas]

Resistor plug is the plug that is used when you have a radio--Autolite 306 and 303 are listed as resistor / spark suppressor plugs.

Autolite 295 is the standard plug

[Barabbas]

Brain fart--I should have typed "noise suppressor" --not spark suppressor...obviously you want a spark

[Joe Flanagan]

I have Autolite 306 plugs in my engine. So I guess I should gap them to .035?

[desoto1939]

according to Autolite.com  the 306 is gapped to .025  not .035

 

Also check your service manual for your car. Inthe back of the book there should be a section on tuneup and spec and it should also list the gap for the plugs.

 

Rich HArtung

Desoto1939@aol.com

[Plymouthy Adams]

gap is proportional to the voltage delivered from the coil..and the tune up reference is based on stock values..