I'm hoping to restore a set of Cylinder heads from an 1970 Rover P6.
I've never done this sort of thing before and was wondering what to look out for that can make them irrepairable?
At the moment they're covered in old thick,sticky engine oil and it seems that the exhaust ports where the exhaust gaskets are, the ports at each end have a white chalky-like substance in them.
Hi
I presume you want to retain them for originality reasons on a restoration? just unless there is some huge pressing reason like that I would swap them for SDI/ later Range rover heads as they are a huge amount better and cheep as chips.
It is the same procedure regardless of which heads you start with. . . remove all bits of old gasket and ally oxide (the furry stuff) with a scraper (DIY paint scraper is fine) being carefull not to dig any big holes in any of the gasket surfaces and brush off any loose dirt with a wire brush/ floor scrubbing brush just get all the loose crud off (dont wet it yet). Pull the valves out of the heads. Next spray everything in Fairy Power Spray, yes the stuff for removing lasange from baking dishes. Leave for about 20 minutes, then wash off with the help of a stiff paint brush and loads of water, if you have a jet washer then all the better. Go back and spray again with fairy power spray any bits that have not come clean and wash off again. Locate the oil ways in the head and run a bottle brush up and down these to get them thoroughly clean. If you have access to a Dish washer, shove them in there on a fairley vigerous cycle. Heads should now be pretty clean !
Using a straight edge and feeler gauges establish if the heads are reasonably flat, a few thou out is not a worry at this stage, 10 thou out and you probably want to bin them.
Look at all the valve seat inserts and the valves (I hope you cleaned tham ain the ame way as the heads) for signes of receeded valves cracked/ burnt seats note down any issues, if the heads between the seat inserts are cracked, it is the bin for them. Burnt/ receeded seat inserts can be replaced.
locate all the tappings for bolts and studs in the heads and run a thread chaser down each one to clean it, including the spark plug holes, If any are pulled/ stripped then helicoil them.
Next job is to replace the valve guides. Find someone with a hydraulic press and an oven, stick the heads in the oven and bring them slowley up to about 120- 150 deg C with a stepped bar that locates in the centre of the guide press the guides out. (from the chamber side) do not bash them out with a hammer, particulally P6 heads will not survive bashing out the guides with a hammer. If you are going to replace the seat inserts, press/pull/cut them out at the same time, you may want to farm this bit out. If the heads are not flat, (more than about 5 thou out) skim them now.
Next put in new guides then seat inserts, then cut the seats making sure all end up cut to the same depth, relative to the head surface.
Reassemble valves and springs with new springs, collets and caps, valves can be cleaned up with an electric drill and emery if in fair condition but really new is best. Lap the valves in with a stick with a sucker on it and some laping paste, this should not take more than 30 seconds per valve if the seats are cut properly on the heads and the valves, if it takes longer then check out to see what is wrong.
For P6 Heads don't bother doing anything but a simple referb a fully ported set of P6 heads flow less than standard SD1 RR heads they are not worth the effort.
Best regards
Mike
Hi Dave
Am just about finished on this very same job albeit with SD1 heads.
Nitromors paint remover works incredibly well with caked/burnt on oil deposits and you don't get the hassle from SWMBO.
I bought a big plastic linen bin and use that as a wash tank for heads.
You can wash off with hot water and some clothes washing powder which gives a nice final wash before blowing dry with compressed air.
You could also match the inlet ports with the gasket which will give a better flow into the runners which will help a little with power.
It just depends on how far you want to go really and how comfortable you are with doing this kind of work.
Cheers
Paul
