The V8 Owners Forum -

ChrisJC wrote:

sidecar wrote: Are you saying even a low-tech Rover amp that's stuck on the side of the dizzy can carry out the task that you described above? If so you can knock me down with a feather! (and I stand corrected!)

Pete

I hereby knock you down with a feather!

If you prise one open, you'll find it's not as low-tech as you imagine.

Which is one reason I can't understand what the attraction of some 'polished billet super-duper' yet points based aftermarket distributors are.


Chris.

I've got back up now!

I totally agree about the points setup. I hate the dual points mallory setup with a passion.....it's total crap in my humble!

ChrisJC wrote:I wonder if the condensor on a points ignition somehow controls the field collapse.

Chris, As the points open they draw a spark which tries to prolong the current flow through the coil and also erodes the contacts.

The condenser across the points, previously closed, now see an open cct and immediately provides an easier temporary path to earth for the current to divert it away from the opening points, killing the spark and hastening the reduction of current through the coil.

The size of the condenser in microfarads will affect how fast that reduction is, depending also upon the coil impedance.

So the time related interaction between the coil impedance (resistance) and the condenser capacitance, will be chosen by the ignition designer similar to that seen here.

http://radioelectronicschool.org/files/ ... s/t=cr.gif

Gotcha!

Chris.

Ramon I understand half of what you have said but you are a bit of an electrical genius- so I shall pick your brains about Aldon coils, HT leads, amplifiers etc etc when I get to the sparky side of things!!!

Thanks guys for this info. Consensus of opinion seems to be the power amp is not all it's cracked up to be and not really worth splashing out on. The money RPI are asking for this item seems like it could be better spent elsewhere, maybe on an MSD 6a or some other form of more cost effective ignition upgrade.

Hi Guys,

Just a quick note on the RPi amp.

They run an advertising spin stating that you can use an "advance by retard" function.

Now what that means is that you cannot work out when a spark is needed in advance of when it is really needed due to variable such as revs and vacuum etc... so...........

If you have LPG then you want an earlier spark and a big one is better (easy lads) - so big early bang.

Now when you flick back to petrol, later spark needed than you do for LPG but big spark is still good to break down the tension and ignite the mixture.

How do we achieve this - the advance by retard principle is that you set up your ignition for LPG, when the fuel is switched BACK to petrol then there is a delay in the spark delivery relevant to need.

Thus you can get a good big spark for LPG on time every time and a good big spark later when on petrol.

If you set up the ignition to be bang on for Petrol, then you cannot work out how early you need the spark when on LPG thus - they spin the A&R amp as a big sparky thing that meets the needs of the gods and all other wonderful things.

Funny how RPi should really be Readily Proffered Information as they really will sell you everything you don't need but convince you that you cannot live unless you have bought at least one of everything in their stock range.

Well I might think that's not totally true.

Doc