Calling all Xflow Xperts -

1: Has anybody experienced problems with unleaded conversion of this engine?
2: After conversion, any changes needed to the timing degrees?
3: Any other mods required?

TIA
Dick

you only normally get probs if the engine is used at high revs for long time or if the valve seats have been recut.
i have used a lead replacement made by WURTH and never had a prob

We convert maybe a dozen heads a week to unleaded but then we carry out a lot of classic rebuilds etc.

My advice is that unless you are having the head off for some other reason then do as Conrod suggests and use an additive. If you use a good one such as Millers (haven't experience of Wurth's) then they are good.

If you are having the head off for say new valves or something then I think its worth doing the proper conversion. If someone brings us a head and their valves, if valves or OK, ie they will grind, we fit hardened seats, cut all the seats, vaccuum test etc, build it back up for £75 + vat. (Crossflow, MGB etc).

If you do all that, maybe fit new springs, pay for the gaskets etc, you are a fair while getting your money back over using a lead substitute. Don't forget even if you don't run with an additive it will still take a fair while for the seats to recess and if they do eventually give problems then have the job done then.

Finally don't get sucked into believing that unleaded conversions also require that you buy new "special" valves or need bronze guides, - You don't!

Although I don't in any way claim to be an expert, I thought I had heard that running unleaded will require a little ignition advance, is that correct?

Kingr

Ref : Ignition timing. With an unleaded conversion you may need to run about 3 to 4 degrees retarded against std settings. That said if you are running a modified engine as we usually do in our Locosts etc then there is no such thing as a standard setting.

Thanks everyone for this feedback, and for David Walker's in particular.