I'm working on a 1964 Dodge truck with my son that will be a street driver only. It's equipped with a Offenhouser intake, 390 carb, Clifford headers, head milled .100, lumpy Comp Cam, manual transmisson, and 3.91 gears. I have a NOS Mopar Performance distributor that I want to use, but have read about the fast curve they have. If I understand what I have read, it only has one spring. Is the fix just to add another spring to delay the curve, or will it still give me problems? My second question is spark plugs. I thought I might go one heat range colder because of the higher compression ratio. Does anybody have a similar engine that they could recommend a plug. I was thinking a Champion N12Y, OR a Autolite 66. I thought I better stay away from the NGK extended plugs with the head milled .100. Thank you, Richy.

I installed the MP distributor in my '64 Valiant with a nearly stock SuperSix, and yes, the distributor had only one spring. Before installing mine, I temporarily replaced the single spring with the two stock springs from a '79 Aspen. It has run so nice, I've not yet bothered to change anything.

We replaced the one single spring with two slightly weaker springs and we run Autolite 63 or 64.

Mrs Lancer, check your pm.

Ugggh...unless you measured the engine before assembly you may have not done much and can use the ZFRN plugs: I have a 1963 Dodge Truck engine and the stock compression was close to 7.3:1...Milling it .100 would have made it 8:1...I have now taken .125 out of the deck of this engine and another .120 out of a late peanut plug head to make 12:1....LOL

Hopefully you have an A-833OD tranny in the truck as the 3.91's are going to get old behind the granny gear/straight ratio NP435 4 speed (fun in the 1/8 mile though!).

For street driving I would respring the MP distributor with a set from a super six distributor (3874876), or if you can find one, just plug and play that guy at 10-12BTDC initial....Later you can do a little more work to the curve as the combination may want to be somewhat aggressive with the 3.91's behind it.

Good Luck,

-D.Idiot