I'm am wanting to mount my coil directly to my spark plug. I am using the MSD SS coil. Is there any advantage or disadvantage in deleting the plug wire and having a direct connection? Do they even make Boots for this? I haven't found any just yet.

This will be on a 12a with direct fire ignition. (TFIDFIS)

 

Actually, quite a few OEMs have an arrangement that is very similar to what you're considering, referred to as Coin On Plug. In the early days of Project OldTree, I wanted to use Dodge Viper style coils sourced from a Chrysler Concorde. But after finding out that they didn't have igniters in them and the only available 'wires' were the hard plastic ones roughly 8" long, I decided to go with D585s to package everything a bit better. It just worked out a whole lot better this way, especially since I can use stock GM plug wires

 

I understand that coil on plug has been done on many cars from the factory, but they all use a coil pack built in to what connects to the plug. It's one long hard plastic piece.

I can't seem to find the rubber like boots to connect my normal coils directly to the spark plug. All the strait boots I find are made for coil to wire and not coil to plug.

 

Ok here is what I did.


I took an old barely used set of aftermarket plug wires I had from a previous TII. I removed the boots on either end of 1 plug wire and removed the metal clips that snap onto the coil and spark plug. I then shortened the spark plug side clip to about half the length, and then cut off the 90* turn from the coil side. I then fused them together using TIG with no filler. For a boot, I cut down the spark plug side strait boot to the right length. and wa la... Coil on plug boot.

I am half way through making the moun for the igniters and coils. I'll updatye when that is complete...


PICS!

 

Interesting...............

 

Here's an update for my coil on plug set up.

I used two plates of 3?16" aluminum and machined them to fit then welded the two plats together. Because

of the weight of the coils, I used pressed fit stainless steel threaded inserts. I redrilled and

counterbored the coil to use 10/32 cap screws to be the exact length to not sit flush with the backside

of the mounting plate.

The igniters mount directly under the coils hidden away on the opposite side. Since these are so light I

just threaded the plate and used 8-32 cap screws. I milled the cap screws down to also be the exact

right length to not stick out, not just for looks. But they would hit the coils if sticking out past the

mounting plate.

The fins were milled then beveled to aide in the heat dissapation as well as to add some asthetics.The

hole you see in front of the coils on the bottom plate is for the wires to go from the coils to the

igniters. These wires will not be seen when looking from above. The wires that from to anf from the

dizzy will be ran across the bottom side and will also be completely hidden. I will show this in my next

update.

So far I am liking the outcome, I have only the two mounts left to make. I already have one drawn up, I

just need to mill it.


Pics...

A shot of the coils and igniters prior to welding it up to check for fit. And a shot of the SS inserts,

slots, and counterbore work:

 

Few shots of everything bolted/welded up so far:

 

Here you can see the igniters hidden away underneath and a shot of the welds:

 

And here they are for a test fit in my very dirty engine bay, that will change very soon:

 

You can see the finished product on page 4 here. I got a bit lazy to repost it this thread...

https://www.rx7club.com/old-school-o...73-rx2-984536/