Thread: Fuel... Lead / Unleaded... advice

The main benefit of leaded fuel in older cars is the protection it offers to valves & seats on the exhaust side. The inlet is cooled by the incoming fuel mixture so heat is not a problem there.
Lead also helps reduce detonation but that's not really an issue in low compression engines anyway.

If your engine has had years of running leaded fuel, then it will retain a coating of lead (called lead memory) over the valves & seats.
How long this lasts when running straight unleaded depends on a very things.
If you're just pottering around town, then it will last virtually forever.
If you are doing general highway driving without towing or using high reves, then it will last a good few years.
If you're doing mainly freeway driving and/or towing, then it won't last long & an additive is required (or hardened valves & seats).

There are additives which can be used. Some work well, others not so well. I'm sure some here will recommend whatever they use but as a guide, check out the FBHVC (in the UK) who carried out extensive testing a few years ago on these products.

Hope that helps.

I can't comment on how the 2L handles unleaded running, but after much discussion with many 2.25 owners I now run straight unleaded in my vehicles. (the one that works anyway!)

More than a few reliable knowledgeable people have reported no signs of valve seat regression after years of running 91RON unleaded.

If you would rather run a lead additive, it is available from the servo. Look for stuff called "Valvemaster" or similar in the bottle with the orange cap.


As an aside, I am cautious about using ethanol blends in Ambrose. I'm no chemist, but from what I understand, ethanol has a cleaning effect on the engine which may be beneficial in most motors but I figure that 45 years worth of gunk is probably best left stuck where it is not doing any harm, rather than breaking free to do god knows what.

Then again, that is probably redundant and overcautious.

it'll run it just fine till it burns out a valve then its a simple case of retrofitting a higher grade valve set with matching seats. then it'll run on unleaded forever.

Kris,

There are several 'lead replacement' additives on the market, cannot comment on whether they actually work or not.
Mine isn't used that often but has had 'flashlube' added since I got it.
Flashlube Valve Saver Fluid: Flashlube fuel additives Synthetic lubricants for the automotive industry

I remember reading an article in a UK magazine a while back where they researched the different lead replacement additives available in the UK. One of the most important things was to stick to one additive only because each used a different chemical to replace the lead and mixing them in some cases caused corrosion of valves etc. I'll have to see if I can find the article.....

The other alternative, as already mentioned, is to get the valve seats replaced but this would mean an engine out job on the 'F' head 2.0 litre engine.

Maybe run a lead replacement additive but keep a regular check on the valve clearances. If they start to close up then you are getting valve seat regression, you can keep on adjusting but eventually performance will be affected so the engine will have to come out to have new seats (and possibly valves) fitted.....

Colin

There are more ideas on this than there are additives available. FWIW, we had the head reconditioned on our 11A and had hardened exhaust valves fitted, so run this on straight unleaded.

Our S1 however, due to considered advice and opinions, we run on unleaded and use one of the additives, as it has not had the head treatment.

I'm no where near old enough, but wasn't there standard and super petrol around LONG before the unleaded craze hit in the '80's. I thought standard didn't have lead in it, and landies being landies and the motors being low compression would run on any old petrol, especially standard with no probs. From what I hear, series ones burnt out valves anyway.

Would be happy to hear from someone who was there.

CC

I should have made mention of the recession issue.....

run with addatives(even a 1:100 ratio of diesel/petrol will work in the short term)

then once you start to get recession its time to pull the head down and reface the valves. Since the valves are out have them replaced and get new valve inserts...


same deal as when LPG first came out and you could have a super car running on LPG...

if you google for LPG conversion valve saver kits you'll yield a sizeable set of suitable solutions. (including my least favorite option of removing the filter from the crank case ventilation system and letting the engine oil vapour do the work for you.)

1. The Series 1 engines have the exhaust valves in the block, so nothing you do to the head can affect the valve seat recession problem.

2. The Series 1 engines have hardened steel exhaust valve seats anyway, so the problem is unlikely to happen, and replacing the valve seats is not a big deal if it does.

3. The Series 1 engines were designed in the 1930s before leaded petrol became common, so their design did not assume the use of leaded petrol.

4. Valve seat recession is almost never a problem on engines with a compression ratio less than 8:1 - the Series 1 is 6.9:1.

5. In those engines designed with leaded fuel in mind, valve seat recession is unusual unless operated for sustained periods at high rpm and power, such as for long distances on freeways. This is quite unusual practice with Series 1s today.


In other words - for Series 1 Landrovers, I do not believe that unleaded fuel is a problem, even less so than for Series 2/2a/3, and I run my 2a on unleaded without additives, and with no signs of recession.

John