Technical Lead Substitute

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Technical Lead Substitute

The stuff I use has a little measure built into the bottle in the same way as some weedkillers. I find that if I fill up as soon as possible after the red light starts flashing fairly steadily I can get 15 litres of petrol in easily. The most I have ever fitted in was about 20 litres. that makes it easy to work out as the measure goes up in 5 litre stages...I just need to remember my reading glasses as the markings seem so feint.:confused: Once in the tank I am just relying on the 500's natural vibrations (no shortage there) to mix it.

I am currently slightly dubious about the whole issue of lead substitute after a spillage made me wonder what's in it? It seemed just like red diesel which is a heck of a lot cheaper to buy:mad:.
 
Is it necessary to use a lead substitute? What type do you use?
I've never used it up till now but I might start if it makes a difference
 
Being so cheap and reading about preventing valve issues, I figure why not?
Not sure how true it is but this is what the bottle says:

Reduces valve seat burning & wear
Helps lubricate top piston rings
Prevents valve seat recession (VSR)
Helps clean upper cylinder deposits
Provides better valve sealing
Cost-effective solution for classic car owners
Helps dissipate high temperature from exhaust valves
Safe for use with catalytic converters or oxygen sensors
 
Hi,
I don't believe the lead substitute is necessary in Fiat 500 engines.
Unlike a lot of vehicles of the era Fiat had aluminium heads rather than cast iron and the valve seat material used was excellent quality.
Leaded fuel was eliminated in New Zealand in the early 1990's and I have been running and maintaining 500's ever since with no additives and no problems.
When I first started using straight unleaded fuel I checked my valve clearances every 1000 miles over a 10,000mile period with no change- I gave up worrying about it 20 years ago, it has now been 25 years without disassembly and still runs fine.... The later 126 engines are designed for unleaded fuel anyway.
If you do decide to run the additive anyway it is most useful for continuous 'high speed' running when exhaust valve temperatures are highest. Also don't overdose it as you can end up with running issues- especially if the fuel is old.
 
Is it necessary to use a lead substitute? What type do you use?
I've never used it up till now but I might start if it makes a difference

It's been debated here before and many times elsewhere with no definitive answer that I can see. In fact, I previously put forward that rhetorical question, "why not?". But that's an argument you could use to justify all sorts of things with life in general..eg vitamin pills, a glass of wine a day, and many of us need evidence for things (well...maybe not the wine :) ) and there seems not much other than anecdotal about additives.

Apparently the product needs to replicate the most helpfiul attribute of lead in that it stops the micro-hammer-welding of valve to seat that would otherwise happen on every valve rebound and which gradually takes tiny chunks out of the seat.

There is some confusion to me in that the alloy head of the 500 already has steel inserts from new so these may actually be hard enough.
 
It's been debated here before and many times elsewhere with no definitive answer that I can see. In fact, I previously put forward that rhetorical question, "why not?". But that's an argument you could use to justify all sorts of things with life in general..eg vitamin pills, a glass of wine a day, and many of us need evidence for things (well...maybe not the wine :) ) and there seems not much other than anecdotal about additives.

Apparently the product needs to replicate the most helpfiul attribute of lead in that it stops the micro-hammer-welding of valve to seat that would otherwise happen on every valve rebound and which gradually takes tiny chunks out of the seat.

There is some confusion to me in that the alloy head of the 500 already has steel inserts from new so these may actually be hard enough.

Precisely- unlike most comparable '50s era classics that simply ran with valve seats ground directly into a (soft) cast iron cylinder head the Fiats all had alloy heads with good quality valves and hard seat materials.
You may run into valve recession issues if the seats and /or valves have been replaced with poor quality replacements.
It is actually more critical to maintain correct valve clearances than use an additive- the only times I have seen burnt valves on 500 engines were due to very tight valve clearances over a prolonged period- ironically this was many years ago on cars that had been running exclusively on leaded fuel!
 
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