Does anyone know what the proper spark plug is for a Dart 1-014-2 head is? I know the newer Pro 1 castings use a 3/4 inch thread reach plug but unsure if the older 1-014-2 is the same or not? Using a small dental pick i can count 9 threads which I believe is for a 3/4 inch reach but wanted to see if anyone can confirm this?... is the 1-014-2 the early pro1 design?

The older dart heads , took a .460 reach tapered seat plug, like a merc/gm iron head engine. The newer darts use the longer reach plugs.


Are there numbers stamped on the front or back of the head, where the head meets the block ?

The 1-014-2 sounds like a race series head, like the 308/320/360cc versions

MT thanks for the reply. The heads have been polished on the outside so all markings are gone but I believe you are correct that they are the older race series heads... what got me thinking is there was a few longer reach plugs that I found under the seat. The casting numbers under the valve covers are the same on both motors which also crossed my mind that maybe one motor had newer heads or something. Do you know anything else about the race series heads?... all I know about them is the paper work I got from the previous owner says they where ported to 380cc on the long runners and 365cc on the shorts and they have 2.30 intake and 1.88 exhaust valves

The race series were avail in 308, 320, and 360cc runners. Very good head with excellent porting potentional, thick decks, etc. Iblike them better than the pro 1s. The early race series took a .460 reach, then they switched to the long reach around 1999 i believe

Thanks MT as always you are a wealth of motorhead knowledge

Were you running the short .460 reach plugs ?

Yep it has .460 reach plugs in it currently