• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

Is a Coil Just a Coil

Share this page

KVH

KVH

Obi Wan
Silver
Country flag
Online
I just replaced the Coil on my TR4A. I had posted here that I fried everything inside my distributor by leaving my key on.

I'm feeling quite certain that my car is running better than at any time over the past year. True, I replaced my points as well, but I always check the point gap and timing, so I don't think the improvement is just due to tuning.

Could a new coil cause noticeable improvement in engine performance?
 
What type of coil have you installed? A Sport Coil will send more juice out for a supposedly hotter spark and more efficient burn to increase HP slightly. I understand the distributor should have components to handle the added juice though.
 
Somewhat unlikely unless there was a real problem with the old coil prior to burning it out. High voltage coils really only make a difference if you have much higher than normal compression or the like. If you didn't open up the spark plug gap then the voltage wont be affected anyway.
In any case, if you do open up the gap, the voltage will go up and then you will be more likely to discover other parts of the ignition system wearing out.
 
Kentvillehound said:
I just replaced the Coil on my TR4A. I had posted here that I fried everything inside my distributor by leaving my key on.

Could a new coil cause noticeable improvement in engine performance?
Click to expand...

<span style="color: #660000">I doubt a new coil will make much difference.
I've just installed my 8th coil in 1700 miles of driving and honestly
I never noticed any difference between coils when the car is operational.

I think adding the word "sport" appeals to our male hormones but
that's about all.

best of luck,

tinster</span>
 
A friend of mine on another board commented once that:
"Sports Coils are only good for pub points".

As mentioned the performance coils only come into play when you do things like add electronic ignition so you can open up the plug gap... and doing so with mechanical changes like increasing the compression ratio.

A failing condenser can cause a very weak spark. If you replaced it at the same time as the coil you may be attributing the improved performance to the wrong component.
 
This has been touched on by some other replies. You can put the so called "hottest" coil on the market on your engine and it will not deliver any more voltage to your plugs than a standard coil, unless you do 1 or 2 things. Open the plug gap and/or increase Dwell time. A Pertronix, for instance, increases dwell time and allows you to open the plug gap a little. from .025, for instance, to .035 with a standard coil and get reliable ignition.
If you need more plug gap to get an efficient burn, you may need a hotter coil.
If you have a coil capable of producing 40k volts, but your plugs only require 20k volts to arc, that's what the coil will develop.
You might find this article by Dan Masters informative on the subject.
https://www.vtr.org/maintain/ballast.shtml
 
Back
Top