fuel quality plug

[Mat Francis]

Alright so chances are I'm way late to the party. But here goes anyway.

Stumbled across it on Craig's Place (http://www.users.on.net/~craigf/), and found it interesting. Had no idea such a system was in place. Obviously, curiosity got the better of me, so i ran outside to have a look how mine was set. Half to my surpise, i had the 91 octane plug. 10 minutes of fiddling around and i now had myself a 95 octane plug.

Well, after driving the car just then, i cannot believe it. The extra pull from below 4k is unreal. No longer feels like it doesn't want to co operate, and then finally pulls it's finger out and launches. Soooooooo much smoother.

If you haven't checked yours, i highly recommend it. Although it was probably just my ignorance that was the issue in the first place.

[pep105]

Mat, definately noticed the difference between the 3 75 Twinsparks 2 friends and I owned, just seems more lively through the middling to high revs with even more top end sparkle. On the 91 plug it feels flater and more linear in its power delivery. Almost a bit of a weapon.......

[Mat Francis]

More top end 

Haven't taken it over 4.5 yet, a little tricky given the long second gear and current traffic on the roads.

Awesome.

[Mat Francis]

Yes. I had a light blue relay fitted to the red plug. If you pull them apart, all it does it connect the three pins as per the diagram. Did Steve's one have a light blue one too? my quick read of Craig's stuff leaves me with the interpretation that different coloured relays connect different pins. Steve's may have already had the correct one in it?

[pep105]

More top end 

Haven't taken it over 4.5 yet, a little tricky given the long second gear and current traffic on the roads.

Awesome.

Haven't taken of past 4500 yet ? Sorry to hear Mat  In good time mate second gear is long its easy to well exceed the speed limit and do your licence while winding out second

My spin on this is that the Aus delivered 75TS would have run
the blue relay 91 plug as standard given the potential to cope with our mineral water unleaded and the availability of premium.  As the twinspark was available from Jan 88 many euro cars had
issues with compatability with aussie unleaded. By running the
blue plug would result in retarded ignition curve to run the lower
octane fuel and it probably made sense for Alfa Aus to deliver
the car with this setup. On the 95 plug it would run more
advanced ignition to suit the higher octane fuel as per possibly
Euro spec.

I don't know I might be full of it but Ive always wondered about the driveability difference between certain cars and the way they  responded to premium unleaded. Also the aussie road tests of the Twinspark seemed  slower than the euro and claimed figures suggest but I might be looking too far into this

Any way let us know how you go             
 

[Mat Francis]

Steve does run 95 octane fuel yes? Probably a stupid question, but start with the basic stuff as always.

It was my assumption that by changing the plug, the ignition curve should be advanced slightly, as the risk of detonation is lowered, hence the extra go. Whether or not this is how it actually works i don't know, i'm just assuming. I agree with everything you said there Pep.

First pic is the internals of the standard blue plug. As per Craig's site, pins 85, 86 and 87 are connected. Nothing too complicated there.

Second is the 95 octane setup. Again, straight from Craig's, pins 85 and 87.

If you are running it without any plug, it is assumed there is no cat. I don't know what difference that would make, but i don't really want to risk it. When it all eventually ends up in the Alfetta it'll be a different story, but i'll just stick to the 95 setting for now.

I'm not saying i just found 20HP, and it could just be me being too hopeful, but i honestly believe it has improved certain characteristics of the engine 

Maybe if i get really keen later on i'll try and go through the wiring diagram and such to see if i can get any facts on the matter rather than just running my mouth.