Kiwicar: As mentioned I have some spare heads that I'll attempt some work on, and it really won't matter as they're not otherwise needed.
I'll have to check first as I don't know it they're P6 SD1 EFI etc Which of these head types are the best?
As for welding inside the head - I'd love a TIG but unfortunately funds don't quite allow!
Can you direct me to any diagrams that show where needs widening / polishing etc inside the heads? When it comes to top-ends and valves I'm almost completely clueless...
Lazydocker: I'd love to get 16mpg!! at the moment I'm averageing a lowly 11...
Best Carburettor for 3.5V8 in a Land rover?
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The Original Tom
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Hi Tom
the SD1 heads are the only ones worth bothering with, fully ported and worked P6 heads flow less than as cast SD1 Heads.
As for mods, I have put this in a couple of other threads but to go again..... Open up the area immediatly behind the seat with a cutter with an arbour that sits in the valve guide so as to open it up 1 to2 mm (opening the "throught" area) then fit "bullet" guides (you can tidy up the guide support area but don't go mad and do a three angle valve job, If you are replacing the valves use SD1 valves with the narrowed valve stem behind the valve head. Blend all this into the rest of the port and remove any casting marks but don't fundementally change anything and don't pollish the surface leave it rough. Don't touch the short turn radius at all unless you have a flow bench and 20 years of experience.
The next problem is the "push rod pinch" ie the area where the pushrods run up past the ports, this is what really limits these heads and there is not enough metal to really do very much unless you have the flow bench and 20 years experience
. You can unshroud the valves in the chamber by laking the area back to the gasket and making a wider radius but it takes away your already extreamly limited squish area and lowers the already limited compression ratio. If you look on carcraft.com there is an article in the tek section trere is an article on the chevy small block (vortec) porting, well worth a read as it covers the basics of what to do.
I think there are references on some of the old threads to articles on porting rover heads that include sections and pattens.
Mike
the SD1 heads are the only ones worth bothering with, fully ported and worked P6 heads flow less than as cast SD1 Heads.
As for mods, I have put this in a couple of other threads but to go again..... Open up the area immediatly behind the seat with a cutter with an arbour that sits in the valve guide so as to open it up 1 to2 mm (opening the "throught" area) then fit "bullet" guides (you can tidy up the guide support area but don't go mad and do a three angle valve job, If you are replacing the valves use SD1 valves with the narrowed valve stem behind the valve head. Blend all this into the rest of the port and remove any casting marks but don't fundementally change anything and don't pollish the surface leave it rough. Don't touch the short turn radius at all unless you have a flow bench and 20 years of experience.
The next problem is the "push rod pinch" ie the area where the pushrods run up past the ports, this is what really limits these heads and there is not enough metal to really do very much unless you have the flow bench and 20 years experience
. You can unshroud the valves in the chamber by laking the area back to the gasket and making a wider radius but it takes away your already extreamly limited squish area and lowers the already limited compression ratio. If you look on carcraft.com there is an article in the tek section trere is an article on the chevy small block (vortec) porting, well worth a read as it covers the basics of what to do.I think there are references on some of the old threads to articles on porting rover heads that include sections and pattens.
Mike
poppet valves rule!
