Hi have a couple of 4g54 heads, but i'm not sure what models they are from.
I have an M1 and a M4
Help with info please.:confused:

Im pretty sure M1 is leaded TM (or what ever that model was)
My TP has an M4 head, and my sigma has had an M4 head put on it (also from a TP but has had roller rockers put on)

The only leaded Astron II was a GN Sigma.
It that what you meant for the M1 head?

Dunno, might be... :P
Im not totaly sure about the whole M1 thing, only the M4 as i have 2 of them :P

The only leaded Astron II was a GN Sigma.
It that what you meant for the M1 head?

sorry but there were leaded tm magnas. and tm magnas with m1 stamped on the head.

someone was asking about this recently, so check out this thread
http://www.aussiemagna.com/forums/showthread.php?t=38768

Thanks for the link. I didnt know there were leaded Magna's

Just checked and my GN leaded Sigma has a M1 head (factory)

Measured up the M1 and M4 and they are basicly identical. Ports, valves are the same size and shape.

One plus for the M1 is that it was fitted with Stellite faced exhaust valves, whick were dropped on the unleaded heads. My bet is that the unleaded Sigma (86/87) had the M4, same as Magna.
There is just a plug in the back of the Sigma head and rocker cover, where the cam extends thru on the Magna.

There was quite a number of various heads on the 4G54. Magnas ran hydraulic rockers whereas the majority of sigmas, scorpions and pajero's ran mechanically adjustable rockers.
The sigma heads did change over time and probably the easiest way to determine which head you have is to measure the valves and ports. It wasnt til when the GN's were released that the Sigma got the Big Valve Big Port head. This head was available on the Scorpions from GJ I believe.
Which head to run depends on what you are trying to do. For a mild, naturally aspirated motor you would want to stick to the small valve, small port head to give you good torques whereas on the other end of the scale if you're building up a turbo beast then the big port, big valve head is the way yo go. Hope this helps.

I already have a carby turbo on the old girl. Just bought a Magna efi manifold that has been coverted for rear wheel drive. Thats the next project.
I have the M1 head ,which is hydraulic , but have fitted the old adjustable rocker gear from an early 4g54. Thanks for the info.

http://img140.imageshack.us/img140/7403/img6865gy0.jpg (http://imageshack.us)