Technical Unleaded conversion

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Technical Unleaded conversion

MattGibson

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Jan 8, 2012
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I've just bought a 1968 500f which has a 126 engine fitted to it. It hasn't been converted to run on unleaded, so I was thinking about having hardened valve seats fitted to the cylinder head. I've read an article in one of the classic car mags which says it's not a good idea to do this as the head is made of alloy and the seats can detach over time. Has anyone had any experience of this? Conversely, has anyone had the conversion done and never had a problem with it?
 
Hi Matt,
Speaking from my experience of driving 500's for over 20 years I wouldn't worry about running on unleaded fuel without modification.
Leaded fuel was removed from sale in New Zealand in the early 1990's and I have driven numerous 500's and 126's for years as daily drivers with no additives and no ill effects.
The important thing to check is that your valve clearances are correct (not too tight) as this will cause burning of the exhaust valves but all 500/126 heads run seat inserts as they are alloy heads and the materials are of excellent quality.
Generally most 500's and 126's don't do many miles these days anyway so set the valve clearances correctly and just enjoy your car- in the unlikely event that you experience a loss of compression due to valve or seat wear you can upgrade the Valve and seat materials at that point.
Regards, Damon
 
Thanks Damon. I'm looking to upgrade the engine shortly to a 695 (similar to Bambino's) so was looking at fitting larger intake valves. I'd just thought about having the valve seats hardened while this was being done.
 
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