Advance Weight Springs

[layada]

What MSD advance spring combinations are people using?

I inhereited the 383 engine with 16 degrees static advance and two silver lightweight springs on the dynamic advance. A heavy right foot and with low revs and it rattled away like Mrs Doyles tea tray.

Now have retared to 12 degrees static timing, with one heavy silver and one light blue spring on the advance. Running Optimax gas. It's much improved the pinking - but possibly it's now a bit on the soft side.

Just wondered what other people are using before fiddling further.

Tks,

Adam

[davefiddes]

I had my dizzy in bits a few weeks ago to lock out all the advance an get a computer to do the job properly and accurately. As shipped from AS my 425(ish) bhp 383 had two heavy silver springs and a black advance limit bush. This gave an advance curve of 17 degrees @ idle with it all in at 37 degrees @ 3000 rpm.

At least I think the two springs were heavy silver. What is the difference in gauge is there between the two?

Still not had a chance to get on the road but I've modeled my advance map along the lines of the mechanical set up but with the addition of vacuum advance (from about 0 degrees at 80 kPa down to 10 degrees at 50 kPa(13" Hg)). In the drive it idles miles better than before but the proof of the pudding will come in the driving...

[steve_D]

My 407 (508bhp) has a silver stop, 1 silver spring and 1 blue.

Steve

[layada]

Thanks Guys,

FYI

Two heavy springs give it the slowest advance. Max advance being 5500 RPM on a red stop and 3500RPM on black stop - according to the spec sheet.

I'm also running a black stop. With one heavy silver and one blue spring this brings it all in by 3250 RPM.

All in by 3000RPM sounds like it must be the two silver light springs. With a black stop you should actually be all in by 2250RPM.

Black stop = 18 degrees advance over 0-RPM. However, with two light silver springs, it's already 6-7 degrees in at idle (~1000RPM depending on cam). This needs to be taken into account. This specific config should give a total advance of around 18-7 = 11 degrees advance on top of idle.

So you are running 17 degrees intial with a black stop then, from the spec sheet, it will be 28 degrees total timing. However, the real way to be sure is with a timing light.