Petrol additive /lead replacement.
- Thread starter Boris66
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Colthebrummie
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Yes, it's best to, I've been putting it in my s3 since I had it. One day I'll buy a converted head. The experts say that years of leaded petrol will giver the valves seats protection for quite some time. It's not that expensive, I get mine from EuroCarParts.
Col
Hello Blackburn, OK, maybe its down to personal preference.
Cheers Boris66
Hi Edlandy, sounds like a plan.
Cheers Boris66
wireman
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If you advance the timing (someone help me with the correct setting 3degrees BTDC rings a bell) it can help the slower burning unleaded thus saving the vales a bit longer.
rob1miles
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I think its the other way round, retard the timeing for the faster burning unleaded, I think the real message here is don't trust us, check!
wireman
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Ha Ha, yes. That's what google is for!
jamesmartin
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exactly if ever it does ,which is for steel exhaust seats
wireman
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Took my own advice and googled this:
https://www.lrukforums.com/threads/ignition-timing-settings-for-unleaded-2-25-petrol.106480/
6 degrees before seems a good starting point
https://www.lrukforums.com/threads/ignition-timing-settings-for-unleaded-2-25-petrol.106480/
6 degrees before seems a good starting point
Colthebrummie
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All I know is, I didn't use the petrol additive at first cos it didn't occur to me, I don't think the previous owner did either. After a while it was running rough and backfiring despite me fiddling with the timing and the points settings. Eventually, I started using the additive and after a couple of tankfulls of petrol with the additive the engine started running smoother and no backfiring. If it was as simple as altering the timing settings, why did everyone have their heads converted in the 1980's when unleaded petrol came out?
Col
Col
Good point Colthebrummie
Thanks Wireman.
Thanks John S, I'll look into doing this.
Cheers Boris66
wireman
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I agree that an unleaded head with hardened valve seats is the correct long term way to go. But if cash is at a premium while saving up for a new head surely advancing the timing will make the current head last a bit longer. 30 years or so of leaded fuel will give the head a certain amount of 'lead memory' and if the engine isn't used for a lot of towing or 'high speed' motorway work then it should last a few years. As others have said some heads are still running fine years after the demise of leaded fuel without modification.
Colthebrummie
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The trouble is leaded petrol hasn't been available for about 30 years so all lead memory will be gone by now. The additive is only about £5 for 4 tank fulls of petrol. If you are that hard up, you should get a pushbike.
Col
Col
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don't forget that 4 star was 98 octane, standard unleaded is only 95. 'lead' was an octane booster as well as doing the job of protecting valves.
You'll need to retard the timing to avoid detonation.
This link is a good read
https://www.classiccars4sale.net/classic-car-how-to-guides/restoration/a-guide-to-unleaded-additives
You'll need to retard the timing to avoid detonation.
This link is a good read
https://www.classiccars4sale.net/classic-car-how-to-guides/restoration/a-guide-to-unleaded-additives
