Spark plug wires question for 39 D-15.

So I've been "googling" what kind of spark plug wires to get for my 39 D-15 213A flathead six? Is it 7mm or 8mm? I see speedway have a flathead universal spark plug wires kit but still unsure since I've seen no recommendations. Reason I ask is I've sunk a bunch of money into my 64 1/2 mustang and believe me, 65 and 64 1/2 are not the same when it comes to parts. So I'm more cautious, trying to make less mistakes.

Any help would be appreciated.

I can't answer your question about 7mm vs. 8mm but here's what I did for my SD220:

I bought this universal 7mm wire kit for about $10:
http://www.oreillyauto.com/site/c/detail/OMS0/9996.oap?ck=Search_9996_-1_2723&keyword=9996

It has everything you will need and includes a choice of angled or straight jackets for the distributor end. I had enough wire left over that I could probably make another set if I had more boots and contacts. If you are worried about messing it up, buy the 8 cylinder kit to get some extra parts:
http://www.oreillyauto.com/site/c/detail/OMS0/9998.oap?ck=Search_9998_-1_2723&keyword=9998

I also bought this crimper:
http://www.oreillyauto.com/site/c/detail/CTI0/85594.oap?ck=Search_85594_-1_2723&keyword=85594

It is not as good as the kind you use in a vice but it worked just fine. Use real wire cutters to cut the wires, not the cutters on this tool. Also, carefully use a razor knife to roll a cut into the jacket, then work it off slowly.

For about $20 and 2 hours I have a nice set of wires that fit perfectly.

Fresh from the Box

Ready to Go

Want something fancy? Here you go:
http://enginebarn.myshopify.com/products/cloth-covered-spark-plug-wire

One thing to mention, you must use a solid or stranded copper core wire on these old coil and points systems, not a RF suppression core wire. My cables measure less than 1 ohm resistance. An RF core, on the other hand, will come out at around 10-20 thousand ohms resistance for the same length. You will get a weak spark and have trouble starting in cold weather. Ask me how I know...

Thank you AZD. I was just looking at speedways and your kit idea is about $15 cheaper even with the crimper. I knew I joined this forum for a reason, already saving money on my project!

I bought similar from Summit Racing for one of my vehicles. The custom approach is great as you get nice clean install and not a bunch of universal excess wire looping.

The main reason I did mine this way was to avoid the big mess from a set that almost fit but not quite. And for the price the kit was very nice. Quality parts and the wire is USA made. The store didn't have it in stock but got it from their distribution center in 24 hours.

I bought the wire set but the crimper I had to go elsewhere's since corporate no longer ships them to store and shipping was about the same as the crimpers at O'Reillys.