As you can probably guess from my sig, I am in Saudi Arabia. My 1998 Discovery V8 had badly warped cylinder heads, so I have had them skimmed. Unfortunately, I think they have taken them down to 0.5 mm below the limits (which incidentally is allowed to be 0.5 below the new size).So they are now 1mm below new if I have read the manual correctly.

These are 10 hole cylinder heads. Engine serial number is 36D51097C, compression ratio 9.35:1, and uses composite gaskets.

Parts are expensive and hard to come by out here, so I would still like to put these back if possible. Does anyone know how critical this limit is? Is it likely to cause damage, or is it a question of risking higher compression and pinking that perhaps could be solved by retarding the ignition by a degree or two.

If this was a suffix B engine, I would be just within the quoted limits. I presume from the engine serial number that this counts as a non suffix B engine.

Would appreciate some expert advice

Thanks

Bill

I reckon with 1.0mm off the heads, that will take the cr from 9.35 to 10.15.
I run 10.4 on my V8 and run on 97ULG (instead of std 95ULG) and when hot get pinking on accel above at about 3000rpm. I can't adjust the timing on mine (its a thor), but you can adjust the timing. If you can get 97ULG, use that. If the engine still pinks back it off a couple of degree. If you can't get 97 or higher back it off about 4degs. You need to listen to the engine and back off the timing until you only get light pinking on accels.

DavidG - Many thanks for your reply. You have greatly re-assured me. Unfortunately you can only get 91 and 95ULG out here, but at least I now know I can put these heads back.

I would still love someone to tell me if a suffix C engine is like a B but with further changes, as I am actually within limits for a suffix B engine.

Anyone got any info please?

Cheers

Bill