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I've read that putting on 4g54 heads onto the 4g52 can change the compression. Does anyone have personal experience with applying a head from a 4g54 II to a 4g52? I'm still trying to find a donor magna atm.

Secondly, are the ports and values on the 4g54 heads bigger than the 4g52? I was under the impression they were. Which was why i wanted to do this, save me having to pay for them to be opened up. Supposedly the 4g52 heads don't have much room for opening up either.

Any guidance on this would be much appreciated thanks.

I believe all Astron 1 heads are the same, with slightly different cams. Astron 2 have a larger combustion chamber to suit the flat top pistons. Putting an Astron 2 head onto a 4g52 will result in a lower compression ratio.

The later heads do have bigger valves, ports and so on. The preferred heads being the M7 castings from the TR Magna which also have roller rockers, though I have heard of people liking the TS heads however these require different pistons.

All you need to know should be in this thread.

http://www.sigma-galant.com/viewtopic.php?f=30&t=3970

I have a TP magna 2.6 astron 2 full injection conversion kit at work (brisbane) if you are interested

Cheers mate, I'm sticking with carby though. Thanks for the info guys.

C_Fernance wrote:I believe all Astron 1 heads are the same, with slightly different cams. Astron 2 have a larger combustion chamber to suit the flat top pistons. Putting an Astron 2 head onto a 4g52 will result in a lower compression ratio.

The later heads do have bigger valves, ports and so on. The preferred heads being the M7 castings from the TR Magna which also have roller rockers, though I have heard of people liking the TS heads however these require different pistons.

4G52's all have flat-tops anyway, don't they? I'd have thought it shouldn't make too much of a difference if that's the case, depending on whether or not the A2 heads have a 2.6 bore chamber diameter?