Is there an easy way to tell if your engine's been converted to unleaded?

[voicedude]

Just bought a lovely '68 Moggie for the wife's 50th. And I am going through its mechanical stuff. The guy I bought it from had it for 8 months and never added lead replacement. Without taking off the valve cover and actually looking at the exhaust seats is there an easy way to know if it has been converted?

[les]

I don't think there is a reliable way to tell without removing a valve, putting a camera down an exhaust port would not be conclusive. Not always easy even when you're looking at the seat.
However unless you run up and down motorways standard seats seem to cope ok. Something to do with 'lead memory' from past usage of leaded petrol.

[ManyMinors]

Don't worry about it. I know mine has not been "converted" but it runs perfectly happily on unleaded fuel and has done for years. I don't use any additive and it is driven regularly on both long and short journeys. Have fun with it!

[paul 300358]

I converted mine earlier this year, it was only because I had the head off. I'm not convinced that it was worth doing as it cost more than the head and valves. One of the well known companies sell a conversion gubbins which adds tin? They then sell the vehicles as fully converted, I actually think that its a bit of a con.

You may be better following the advice which is well documented on this forum of setting the exhaust valve gaps to 0.015" and checking every 3,000 miles.

[voicedude]

Don't worry about it. I know mine has not been "converted" but it runs perfectly happily on unleaded fuel and has done for years. I don't use any additive and it is driven regularly on both long and short journeys. Have fun with it!

Just what I wanted to Hear! Thanks!

[voicedude]

[MorrisMinion]

I was considering an unleaded head upgrade to my 1965 convertible until an old pal whose business is the restoration of 1960s Astons told me to to run it on super unleaded which is a similar octane rating to the original 4 star. I’ve run like this now for 3 years with no problems and it also eradicated the problem I had with pinking. It may cost a bit more for the fuel but it’s less than the cost of a new head. Enjoy the car as it is.

[Myrtles Man]

The following extract from a 2011 article on the subject by Classic Motoring may be of interest here. Also, I seem to remember that the engines chosen for the FBHVC lead-replacement tests were in fact the good old A-series:-

'Well, according to one fuel expert, Millers Oils, classic car owners were mainly concerned with the problems of valve seat recession where the lack of lead caused the valves to hammer themselves into their seating. However Millers says this has actually has been far less a problem than the industry initially predicted, possibly due to the relatively low mileages covered by the average classic car user.But this preoccupation with valve recession led many to overlook the danger of burning a fuel with an inferior octane rating to that which your car was designed for, and so promotes potentially fatal detonation as a result. Lead - in the form of Tetra Ethyl Lead (TEL) - was initially developed for use in aircraft engines as a means of gaining large increases in power output without destroying the engines through detonation or pre-ignition (pinking). When the leaded fuel was made available for road use, it was soon found that vehicles using Ethyl petrol did not need their valve clearances adjusting as much as those running on normal petrol did. That is why many motorists today believe that lead’s only use in petrol was for such valve seat lubrication, and why they assume that putting hardened seats in means you can safely run unleaded petrol. This is not so, particularly on higher higher-powered engines that are not so tolerant of low grade petrol such as Lotus Elans, Rover 2000 TCs,Triumph Dolomite Sprints and many late 80s turbocharged engines such as the Ford RS Turbo CVH unit. Here’s another myth exploded. Over the past 20 years octane ratings have gradually been eroded; remember good old Five Star had an octane rating of 101 - and you can’t beat a dollop of lead! Contrary to popular opinion,a good number of older engines will not run as well on 98 octane unleaded (and even the new 99 octane as introduced by supermarket giant Tesco) as they will on 98 octane leaded, even though it supposedly has the same octane number rating, claims Millers Oils. This is due to the differing efficiency of burn by the shape of the combustion chamber, which is controlled in part by the design of the cylinder head. Simply put, unleaded fuel burns less smoothly than leaded and the toluene and benzene, which is added to the fuel to act as a lead substitute, burns to form what are called peroxides. Unfortunately peroxides are inherently unstable and explode, forming shock waves that cause detonation. This explains why engines designed to run on unleaded from the outset feature sophisticated knock sensors, which retard the ignition setting at the onset of harmful detonation. Older engines did not have the luxury of such knock sensors and relied on one of the properties of lead to prevent pre-ignition and subsequent detonation - as lead burns, it forms oxides and these slow down the rate of burn and prevent detonation, oxides also lubricate the valves.Hence the ‘burn’ of leaded fuel is much less aggressive than unleaded and the risk of detonation is considerably reduced.'