Dist cap and plug wires

[JohnnyO]

Ok, so I want to replace my plug wires and dist. cap. I wanted to get the Cobalt Wire set sold through Moss, it says "early sprigets must use top entry cap" my cap now is the side entry type... my question is, are these two types of caps interchangeable? Can I just replace my side entry cap with the top entry cap and that's that????

 

[Billm]

Yep-
A side entry cap is better for a RHD car to keep the wires from fouling the steering column but on a LHD car either cap can be used. They both take 8mm wires.
Not sure why Moss said that, doesn't make sense to me.
BillM

 

[aeronca65t]

With the Cobalt wires, I'm pretty sure the set already has the metal connectors at the distributor end pre-attached (for the push-in style cap).
The side-entry cap just accepts plain wire (as I'm sure you know).
I guess you could cut off the connectors and push the Cobalt wire into the side-entry cap (but I'm not sure how well resistor wire works in that setup).
I prefer the side-entry caps, but I run always solid-core (non-resistor) wire.

 

[Pythias]

As long as you're changing to top entry for your cap, go to Advanced Distributors on the web and get a cap that has BRASS instead of steel or aluminum for the contact points. May as well pick up one of his "RED" rotors at the same time. You'll be glad you did.


NFI

 

[JohnnyO]

Ahhh too late Bill, I already ordered from Moss, but I think I might just go ahead and get one of those caps with the brass contacts from Advanced Distributors, guess I'll just have a spare cap now.....

 

[JeffS]

Here's the reason for the disclaimer:

If you use the carbon core style plug wires with a side entry cap, you will puncture the carbon core with the cap's retaining screw. If you so much as scuff the carbon core, it will begin breaking down from arcing and burn up in short time. By pushing a screw into the wire, you're shortening the life of any carbon core plug wire dramatically.

Now here's the twist: Solid core plug wires as normally used in a side entry distirbutor cap throw off large amounts of RFI noise. We all know th enoise - it gives you the great whine on the AM radio dial. It also affects electric tachometeers and more inportantly, it can shield a Pertronix unit from reading its own magnetic signal. Yes, it WILL cause misfires when you use a side entry cap and solid wires with a Pertronix, and occasionally a Crane or Lumenition ignition kit (but far less so since they're optically triggered). I'v eseen TR4s that won't run above idle speed because of solid core wires used in conjunction with a Pertronix.

My recommendation for any car that's a driver: Use the later top entry cap (Lucas DDB-106) with carbon core plug wires no matter if you use points or electronic ignition. Keep the NOS parts for the car shows. Perfomance and reliability will be its best.

Yes, I sell great brass terminal caps and I make the red rotors that just never fail, but this is just as important. Update your plug wires and cap if you have the old side entry style. Just make the change the next time you need a tune-up.

 

[Pythias]

Thanx Jeff... hey your parts came in time for me to go but now I can't.. see my other thread on that.... I use the Bosch wires with right angles out of the cap. I can't think of the model number now, but i've been really happy with them.