Capacitor for coil - 308

I am replacing my original coils with the Bosch Blue coils. There is a 220 uf cap on the Marelli coils. Is this needed if using the Bosch coils? Thank you.

Jim

 

When you say there's a capacitor on the coil do you mean connected between the 12v +ve of the coil and ground ?

If that's the item then it's there for radio frequency intereference suppression.

You could try the new coils without the capacitor, but if you get clicking on AM/FM in time with engine speed then re-connect it.

Make sure the capacitor is not on the contact breaker side of the coil, this will lead to rapid wear of the points. (I'm not familiar with the 308, am assuming it has a regular set of contact breaker points).

Hope this helps,

RF.

 

When my mechanic installed the Crane Cams XR700 units on my 78 308GTS, he also installed new Bosch blue coils, he removed the ballast resistors.

 

OK jw we need a little more info. So if you have a 78 you need to let us know if you still have the points and what you are doing. I have replaced my points with a pertronix system and have installed bosch blue coils. I remove the small cap. and am not using the bypass resistors. So a little more info please.

 

OK...more info. My car has std. points, and I am only changing the coils (one of them is acting up) I am not referring to the condensers. It is a capacitor between the + side of front side coil and ground. I am not using ballast resistors as the Bosch Blues have internal ballast resistors. Thanks.

 

What do you mean one of the coils is acting up? What is it doing?

 

One of the coils worked intermittantly, so I replaced both. I have the new coils in the car, and the problem is gone. I just would like to know if I need the capacitor. Thank you.

 

The CAP that you are talking about is for noise surpression. You can leave it in or out if you want. Also I don't recall if the BLUE coil had internal resistors. I would not bet on it. If you look at the circuit for the coils the by-pass resistors are taken out of the circuit on start up so you have 12V going through the ignition system. After you release the key at start the by pass resistors are active lowering the volts to around 9V in order to preserve the points. So when you hook up the BLUE coils you jumper out the start and bypass circuit and have 12V at all times. The car will rune but you will burn out the points in a short time. I used the BLUE coils after I converted my points to Pertronix breakerless ignition. They have no problem with 12V coils. I also left out the CAP and I don't get RFI noise. My 2C

 

hmmmmm......my understanding is that the blue coils have the internal ballast resistor and the red coils do not. I'll have to double check that. Thank you.

 

For '78~'79 US 308 they eliminated the bypass stuff for starting so (when stock) the ballast resistor is always in series with the coil primary winding (but they did use a more "oddball" coil too -- although I don't know the details of the difference and how it would or wouldn't relate to your original question).

 

I have them installed now without the ballast resistors (that are attached to the original marelli coil brackets). I measured the voltage across the coil with the engine running....it is less than 4v .... voltage to the coil is over 12v

That seems low to me....too much internal ballast?