MG T-ABC

Although I`m specifically writing in regard to a TF1250 what is the general opinion regarding having a head "converted" to unleaded. A local mechanic has referred to a problem with valve seats breaking free. The consequences of this happening could obviously be catastrophic on a virtually irreplaceable item.Thoughts please.

I've had this done on the exhaust valves of just about every cast iron head I own. If done properly there should be no issues.

General consensus likely to be that if your head has been used hard and has notable exhaust valve seat recession, then adding hardened seats is needed. If no recession, then just make sure mixture is not lean, and timing does not allow pinging--either of which will cause exhaust valve problems. You don't say if your head needs rebuilding or is working fine.

I have had several cars originally built for unleaded that never were "converted" for unleaded, and they lasted forever on unleaded. Overly lean mixture and/or pinging is the kiss of death for these engines with unleaded fuel.

I do not convert to hardened seats unless the existing seats are beyond grinding in. If you were putting 10,000 hard miles a year on the car than it could be an issue, do you think you will drive it a couple thousand per year trundling around the back roads as most of us do?

I use a lead replacement additive. My blown TC happliy digests a dose of Flaslube in each fill up.

I understand that valve seat recesion is only a problem if you run the engine at high revs for long periods or do high milages.

Our cars probably don't get this treatment so will probably be OK without hardened seats.