Classic cars forum & vehicle restoration.
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nickjaxe
Joined: 14 Jun 2013
Posts: 36
Location: North Cheshire
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 Posted: Thu Aug 13, 2020 8:30 am Post subject: Book static ignition timing and modern day ignition timing. |
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Hi guys...just wonder if any of you guys have had to move away from manufacturers book static ignition timing.
Mt 1969 2 stroke BSA Bantam when it was built had a book static timing of 16.5deg btdc....
It doesn't like that setting these days and needs to be around 15 dg BTDC.
I was wondering if anybody else has found the same.
I am thinking its down to the ethanol in our petrol...some say it has a slightly slower but rate some say a faster burn rate.
Love to hear your comments.
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My other hobby. |
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alastairq
Joined: 14 Oct 2016
Posts: 1954
Location: East Yorkshire
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| Posted: Thu Aug 13, 2020 8:49 am Post subject: Re: Book static ignition timing and modern day ignition timi |
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| nickjaxe wrote: | Hi guys...just wonder if any of you guys have had to move away from manufacturers book static ignition timing.
I was wondering if anybody else has found the same.
I am thinking its down to the ethanol in our petrol...some say it has a slightly slower but rate some say a faster burn rate.
Love to hear your comments. |
First off...it has nothing to do with ethanol, as such.
It has everything to do with the components that make up 'petrol' over the past 20-30 years.
Petrol [today] is very different stuff to the petrol sold back when your Bantam was new.
Plus, as engines wear, the factory settings become but a guideline.
Every time you put fuel into the tank, the stuff is actually slightly different to what went in before...and so on.
If you really want to now the truth of the matter, then I suggest buying yourself the book I link to below?
It contains the itemised results, and conclusions, of tests carried out at Manchester University on the effects of modern petrol, on old technology engines.
The tests were conducted on a good condition, but old, MG XPAG engine.
Surprisingly, ethanol , as such, improves the running of old engines to a greater or lesser degree. [it is not new..but was available in fuel sold before the 1970's, under the brand name of Cleveland Discol]
Where ethanol is seen as the 'devil' is with its effects on old fittings, rubbers and gasket materials...which, to be fair, all should have been replaced long ago..and replaced on a regular basis.
It also gets attracted to water......water 'sucks out' the ethanol content from the fuel.....which creates droplets of quite acidic materials..which,being water, sink down to the bottom of tanks, below the petrol...to burn away at the tank's material. Glass Fibre tanks don't like ethanol at all, either [and should have been replaced a long time ago anyway?].
So, to get back to the question of timing? Yes..Every engine should have it's ignition timing [and fuel mixtures] adjusted to suit that particular engine. The manufacturers figures must be taken as a starting point, or guide, only....as the criteria which prevailed at the time the figures were calculated, no longer apply.
Mixture strengths need to also be looked at.
Whilst ethanol [in particular] has been around for some time in all[or most] pump fuel...with the intention to fall in line with other countries, and introduce the option of E10 fuel...[10% ethanol]...an increased percentage of ethanol will cause old school fuel systems to run a bit weaker.
[Modern electronic controls of engines will adjust themselves automatically]
So you might find a benefit from looking at the Bantam's mixtures as well? they may need richening up a bit?
Certainly, any 4 stroke engine will run more cleanly with ethanol in the fuel...as Manchester Uni have proved in their tests.
Link to the book below.....worth buying and reading, if running old engines, and not wiling to rely on unsubstantiated chatter in media and elsewhere?
https://www.veloce.co.uk/store/Classic-Engines-Modern-Fuel-The-Problems-the-Solutions-p151478624
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Dellow Mk2, 1951 built, reg 1952.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
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Ford Pop chassis, Ashley 1172 bodyshell, in pieces. |
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