Ignition Suppression

Post by **MikeNash** » Wed Mar 15, 2006 3:40 pm

Greetings Comrades!
I seek your advice on the above. I've got (and prefer) copper plug leads and coil to distibutor lead with suppressor caps on the plugs. But there's always an irritating background of clicking in time with the engine. I'm thinking FM, worst for Radio 4. (No noise from the heater, wipers or pump.) Perhaps, unwisely I've got the ariel on the offside ie the side where the ignition stuff is. (Less of a temptation to passing vandals when parked.)
I'm not keen on the carbon string stuff, but am I wrong?
What do you recommend? Thanks in advance, and regards, MikeN.

Post by **bmcecosse** » Wed Mar 15, 2006 8:32 pm

If it's clicking - is it not the fuel pump ? Disconnect it for a minute - and see if the noise stops. You can put a capacitor on it. You also need to make sure the outer braid of the aerial lead is earthed to clean metal at both ends.

Post by **MikeNash** » Wed Mar 15, 2006 9:37 pm

No, its not the pump. the noise rises and falls with the revs. Thanks for thought on the aerial braiding though - I'll check that. MikeN.

Post by **newagetraveller** » Wed Mar 15, 2006 10:28 pm

Could it be the dynamo?

Post by **MikeNash** » Thu Mar 16, 2006 7:40 am

No Newage, its not the dynamo. Sorry, I should have included that in my list of eliminations. (And actually have an alternator on now.) The clicks and mush are all in time with the revs so I'm sure (so far anyway) its caused by the ignition system. Perhaps I should look more closely at the distributor.
Do other owners find copper leads with just suppressors at the plugs satisfactory? Its not used on modern production stuff, is it?
Regards, MikeN.

Post by **Pyoor_Kate** » Thu Mar 16, 2006 9:16 am

I didn't find it satisfactory; no. I've got a radio with a 'built in suppression circuit' until I had that I couldn't listen to the radio at all in the car.

Post by **Gareth** » Thu Mar 16, 2006 12:30 pm

I found that the radio reception in Phyllis was absolutely dismal until she had a fight with the garage door... She won, sporting nothing more than a snapped aerial which, when replaced with clean new connections, was much improved.

Make sure it's earthed properly under the wing - that's a prime cause for interference.

Post by **simmitc** » Thu Mar 16, 2006 12:55 pm

It sounds like HT, possibly just one plug / lead. I had a similar problem for years until (under protest) I finally fitted a set of modern leads. Lo, there was peace and no clicking.

Most important is good earth. Try routing the aerial wire without going through the engine bay. Could be worth changing the rotar am and distributer cap. Also try removing (completely) one plug lead at a time to see if you can pin it down to one cylinder. Sometimes fitting resistor plugs (RN9Y instead of N9Y for example) helps.

Post by **minor_hickup** » Thu Mar 16, 2006 7:48 pm

i found that after fitting a set of leads from a golf gti (because im cheap and they were free) the noise on my radio was much better.

Post by **Shawn** » Thu Mar 16, 2006 8:40 pm

I too, changed my leads and found a great improvment. Mine had a terrible mixture of old, hard leads when I got him, Including a copper cored one from coil to dizzy.

Post by **Nigel2** » Thu Mar 16, 2006 8:41 pm

Hello Mike,
Showing my age but I used to install car radios in the 60's (before FM!!). Ignition noise can be a s*d to get rid of. Like you I still believe in 'real wire' plug leads. We used to use supressed plug caps and a supressor in the coil lead, not always very sucessful. Main thing is a decent aerial, well earthed, make sure the radio has a good earth and not relying on the aerial. The idea is to get lots of signal that you want into the radio. Best cure if all else failed was to fit a roof aerial, looks good and well away from the ignition circuit. Back to main thing, good aerial and earths.
Nigel

Post by **MikeNash** » Thu Mar 16, 2006 9:56 pm

Thanks for your advice folks. Will go and check the aerial first -take the point that I need to start with the best signal. Think also that it wasn't a good idea to have it on the offside. Still loath to go to carbon string leads but it may come to that.
But now its dark I'll run it and see if I've any lightning around the dizzy or out of the leads. Should have done that first. Taa again, MikeN.

Post by **MikeNash** » Thu Mar 16, 2006 10:06 pm

Nope, no thunderstorm. Mind you I've still got the low resistance coil and a 36 watt bulb in parallel so its not as dark as I'd like. Will also do a close inspection of the innards of the dizzy. Again, thanks for advice, MikeN.

Post by **Axolotl** » Fri Jul 14, 2006 3:37 pm

"Use a suppressor in the coil lead"- is that a condenser (sorry capacitor) in series with the coil lead I assume you mean on the earth side?

I have a similar HT noise problem, with brand new suppression leads fitted. I was about to resort to resistor plugs, but the suppressor on the coil may be a cheaper answer.

Anyone know what capacity / type suppressor is needed, or a source for ithe right item?

Post by **minor_hickup** » Fri Jul 14, 2006 9:01 pm

Just a thought....coil!

I found an old coil and tried it out on the car....no good, after a good drive I got a slight misfire when pulling away and when I pulled up it was red hot. As I was driving it was causing a buzz on the radio which like you mentioned rose with the revs. Put my newish coil on and no noise.