Well, so why do Renault people tell me to do it and why is everyting ok after about 10000 miles ? Did that job last year and everything went well. They milled off something like 1/10th millimeter. If this causes any problems with the chains - wow. Instead get a plastic header bottle with a low water warning switch instead of those good looking but dangerous stainless bottles. You never see if you are low on coolant with those. Elvis >From what i've read on some volvo forums about PRV's, you do NOT want to have any amount of the head surface removed in any circumstance. >From what i've come across in my research, it causes timing chain problems as even the slightest change in the distance of the cams from the crankshaft will push the chain tensioners to the limits of their ability to keep proper tension on the chain.. You also have to remember the timing cover bolts to both the block and the head, so changing the tolerances between the block and head would likly mean the timing cover wouldn't fit quite right after you torqued the heads down. Granted, i've never actually rebuilt any of these engines myself.. but this is what my research has told me when looking in to what it will take to rebuild the engine in my D Chris VIN# 3209 http://badger.brazi.net/delorean/ To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/