AU I6 cylinder heads - all the same?

[Kryton]

Quick question:
Are all AU I6 cylinder heads the same from Series 1-3 and LPG to Petrol (Excluding all VCT heads) or are there differences with valves etc?

[The Monty]

I might end up being corrected, but I believe the AU HP had a slightly differing head in some way too.

[Kryton]

I was mainly looking at standard heads.
ie: will a S3 head fit onto an S1, is petrol the same as LPG?

[Bossxr8]

LPG heads had hardened valve seats.

[shayne93]

The HP (Factory red rocker cover) head has a different camshaft and has a 'T' for Tickford cast into the front.

[Mr Hardware]

I'm 90% sure the LPG heads were exactly the same as the petrol heads

My AUII is made before the EGAS option was available, and is a Factory Tickford Dual-Fuel

It's my understanding that right throughout the AU production run they just plucked an ordinary AU when it rolled off the production line and then Tickford did the Vialle gas fitout. This was an option available right throughout the AU range.

My understanding is that the Green-Top E-gas motors had no differences to the petrol motors except no holes for the petrol injectors. And i'm pretty sure they both had the same 9.6:1 compression ratio.

[Bossxr8]

There was definitely a different head on E Gas motors, I specifically remember that when they were fitted on the assembly line. They had harder valve seats and possibly better exhaust valves to handle more heat.

[Stav]

The au heads were pretty much the same spec but the hp had a bigger cam to gain 10 odd kilowatts over standard. Between au1 2 and 3 no differences but there are definately casting differences which made the ports flow better . If you go to a wreckers and look into the ports you will see the differences in intake ports . Lpg ran harder valve seats from memory