Lotus Elan

Lead additive

PostPost by: micky p » Wed May 28, 2014 9:07 am

i have a 69 Elan s4 that has been restored does anyone know weather i should be putting lead additive in the fuel
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PostPost by: billwill » Wed May 28, 2014 9:15 am

Depends on what they did to the valve seats when the engine was restored.

If they fitted new seats they will almost certainly have used ones which do not need lead substitute additive, but if they retained the originals, then you should put the additive in your petrol.
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PostPost by: theelanman » Wed May 28, 2014 11:06 am

I always thought the twink had come with hardened valve seats as standard.....am I wrong????
(due to it being a high revving engine.......)


I still use an additive but only because it has the octane booster (Castrol valvemaster plus....)
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PostPost by: rgh0 » Wed May 28, 2014 11:26 am

The original twin cam valve seats were reasonably hard and are OK for unleaded fuel if still in the head especially for the limited mileage most twin cams do these day. Though after 40 years+ there cant be to many heads left with original seats.

Newer valve seats are harder and will last longer on unleaded fuels but unless your planning doing 30 thousand miles a year I would not change seats unless they need it due to wear and recutting. Valves seats really only need changing when they have been recut a number of times and the seat face is now too deep in the head

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PostPost by: 69S4 » Wed May 28, 2014 12:19 pm

There are still some of the original seats in my head - I suppose about half of them have been replaced over the years but I can't remember which ones. When leaded 4* vanished from the pumps I religously used some Castrol additive for years but, as is the way of these things, stopped when the local shop ran out of it.

My mileage isn't that great but I have done a few long trips in the car - Oxford to the Alps a couple of times, West Country etc as well as general running around, and I've not noticed any valve clearance changes at all. If the older seats were that much different to the newer ones I'd have expected any changes to be visible on those ones first but nothing seems to have happened to any of them - so far anyway.
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PostPost by: Chancer » Wed May 28, 2014 12:26 pm

I have long pondered on this subject and given the rarety of these engines and the scarcity/cost of parts like the cylinder head I would probably have erred on the side of caution however your posting is very telling and Worth more than a thousand other exp?riences, thanks for posting it.
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PostPost by: TroonSprint » Wed May 28, 2014 6:02 pm

On the same topic, do any of you use "ordinary supermarket" unleaded or do you go for the higher octane blends? I have never driven my Sprint yet, but hopefully by next spring...... The body went on the chassis this week, for the first time in 37 years.

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PostPost by: theelanman » Thu May 29, 2014 11:05 am

I tend to stay away from the supermarket stuff for the elan due to the content of the supermarket stuff......
high in either Glycols or Ethanols...can remember which.....
but if left standing for too long will separate leaving a corrosive layer which will attack your metals.....
so its the best of shell usually.....

its ok in the daily driver as it doesn't have time to sit and separate.....

my thoughts anyway.......
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PostPost by: Quart Meg Miles » Thu May 29, 2014 11:22 am

TroonSprint wrote:On the same topic, do any of you use "ordinary supermarket" unleaded or do you go for the higher octane blends? I have never driven my Sprint yet, but hopefully by next spring...... The body went on the chassis this week, for the first time in 37 years.

Mike

You need the higher octane, usually only 97 anyway, to avoid pre-ignition even on the original engines so the Sprint definitely does.

My experience indicates that all the fuels have had alcohol in them for about five years and I've been obliged to fit an electric pump in the boot to overcome vapourisation i.e. fuel starvation when the engine is hot. I can hear the pump working hard at times, presumably fighting the vapour, but the engine now never misses a beat whereas I had complete breakdown in traffic before.
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