Dart Pro1 Spark Plugs
1)Autolite 3934
2)NGK FR5
3)NGK BKR6E
The NGK FR5 appears to be an c4 ZR1 spark plug and the autolite 3934 just appears to be a class of spark plug.
So to make sure that I order something that will fit, what spark plug/part number are you using?
Personally i wouldnt use an autolite in a GM but im shure its a good plug. Dart just gives you a couple of choices because they require a gasketed plug as apposed to the conical sealed plug that the stock head uses.
Last edited by LOUDMAN; Apr 24, 2008 at 03:29 PM.
Link
3924 - Stock heat range
3923 - One heat range colder
For Denso:
IK16 - Stock heat range
IK20 - One heat range colder
All the above part numbers meet the following specs:
Thread – 14mm
Reach – 3/4”
Socket – 5/8 hex
Seat – Gasket
Gap - .059
Installation: 21 lb/ft or 2/3 Turn
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Will the taper seat work, yes. Is it optimum, no. It's amazing that one would recommend the incorrect part. Why not use what the manufacturer designed the head for?
Will the taper seat work, yes. Is it optimum, no. It's amazing that one would recommend the incorrect part. Why not use what the manufacturer designed the head for?







