Classic cars forum & vehicle restoration.

[Kelsham]

Hi Jim,
most interesting about the LPG taxis. In my case I was using a low compression MOD engine in my Morris 1800. I was forced to carry out valve repairs after 30000 miles due to performance dropping off.

When I dismantled the head I found the valves had receded into the head.
I believe Practical Classics experienced the same type of failure when testing an early panacea, pellets in tank?

I did drive the car on Motorways and used it to tow a light folding caravan. I also had a pipe leak from the manifold to the servo during this time.
I suspect these activities did not aid long life
I was using Castrol valvemaster at the time. I still use Valvemaster in my 1932 BSA Threewheeler as I believe it helps.

I rebuilt the engine at this time and found that one con rod was deformed and was pinching the crank. Probably due to a failed big end bearing in an earlier life. It shows how poor the inspection was when the MOD engines were rebuilt.

Now all sorted on high compression pistons.

regards Kels.

[richardlw]

I've understood the lead/valve seat problem to be more related to valve spring tension, but can be compensated for partially as we do in large natural gas engines with higher sulfated ash oil formulations, so that there are ashes there to cushion the blow. I don't have to worry as the Corvair already used hardened valve seats in 1960.

I use 25 to 30% leaded aviation gas in my 88 BMW, not for the lead content, but for the octane, since it refuses to run on the 80 octane sold locally. Best performance is right around 30%.
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Richard's Cars - NEW **
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[Phil - Nottingham]

Wish I could get Avgas!
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Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2

[richardlw]

It isn't real easy. Basically two ways:
Either buy it at the time of a local race, when it is available to race drivers (I'm not active, but keep my membership)
or go to the airport and talk to the Major or whoever is on duty in the Air Force, and "buy" some from him.

Try to keep a drum of it at my office. Put 12 liters of avgas in the tank and drive across the street for 30 liters of regular.
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Richard's Cars - NEW **
Motor oil for Flat Tappet Engines
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[baconsdozen]

None of the inline or in the tank boosters work.None have ever been tested by any reputable independant body and found to have any effect other than lightening the purchasers wallet.Why would anyone pay £30 for a couple of air gun pellets to stick in the fuel tank?.
I've used Redex lead replacement additive in my V4 ford since a complete engine rebuild that included new valves and recut seats (so no 'lead memory' to stave off wear).This relatively small engine works hard pulling a heavy motorhome body,the valve clearances have stayed constantin thousands of miles since the rebuild.
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Thirty years selling imperial hand tools for old machinery(Now happily retired).

[pigtin]

Never had a sign of valve seat recession in any of my old cars and I've been using unleaded since the leaded became expensive.
As for fuel going off. My Pinto Engined Ford Camper used to stand all winter with leaded in the tank and start instantly in the spring.
As soom as I wintered it with unleaded there was no way it would fire without priming the carb with fresh petrol.
Any old crappy petrol: be it diesel polluted, or months-old 2 stroke mixture from the boat engine. It all goes in the tank of the 32 Austin 10. It never fails to start.
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Due to the onset of my mid eighties I'm no longer sprightly and rarely seen in my Austin special. I have written a book though. https://amzn.eu/d/7rwRRqL

[Jim.Walker]

I think a lot of the fears about unleaded fuel date back to (some) manufacturers (or Dealers) trying to wriggle out of warranty claims by blaming the use of unleaded fuel when it was first introduced. The fear of it is still prevalent.

Pigtin, has posted his positive experience with unleaded and so have I. But no one seems to take any notice. Yes, valve recession MAY occur on SOME engines, but I have yet to meet anyone who has suffered it at mileages where the use of unleaded fuel has not saved much more than the cost of having seat inserts fitted etc., if they do become necessary. So the best, and most economical action, is to wait until (if) recession happens. The engine will not be harmed in any other way.

You are whistling in the wind Pigtin, and so am I. Though we seem to be whistling the same tune! I believe the additive and gimmick manufacturers are laughing all the way to the Bank!

It is likely that unleaded fuel, loaded with lighter fractions to increase the octane rating will go stale more quickly than leaded, particularly in the typically vented fuel systems of older cars. Best then to leave as little fuel in as possible in laid up vehicles.

Jim.
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Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then!

[baconsdozen]

On a similar topic,I have been using a two stroke oil in diesel in my old fairways taxi.
The oil is said to replicate the lubricating properties of the sulphur which is now much reduced in modern fuels.I have noticed no difference in power but the engine is quieter especially when cold.I use it at 50 to 1 and it seems worth the small extra cost.
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Thirty years selling imperial hand tools for old machinery(Now happily retired).

[Jim.Walker]

Tetra ethyl lead was supposed to "lubricate" valve seats, thus reducing "pocketing".

I am not a chemist, but my understanding of Sulpher in petrol and diesel fuel is that it burns to form Sulphur dioxide (SO2) and Sulpher trioxide (SO3). Those Sulphur compounds, with the engine cold and liquid water from combustion, which exists even at temperatures well above normal boiling point because of the high cylinder pressures in the cylinders, combines with the water to form H2SO4 (Sulpuric acid) and H2SO3 (sulphurous acid). Those acids cause high corrosive wear as engines warm up and are responsible for most of the cylinder wear.

With the engine hot the sulphur compounds are discharged through the exhaust and contribute to acid rain etc.

I have never understood that Sulphur in any form has "lubricating" qualities. Am I wrong? Perhaps someone with better chemical knowledge can tell me?
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Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then!

[richardlw]

somewhere I have a paper that covers this, and I'll look for it later. In my mind is summarized something like this:
Contrary to popular belief, it is not the sulfur that lubricates, but the reason that many low sulfur fuels lack lubrication is that the original, (and cheaper) processes that eliminate sulfur also eliminate (or change) other compounds that lubricate.
The conclusion was that reputable low sulfur fuels today do not suffer from lack of lubricity.

On the 2-cycle oil, I hope at least it is TC-W3 so it is ashless, otherwise it will leave bad deposits on the valves, pistons and plugs. And even at 50:1 it could be leaving carbon in the rings as it burns. But 2-cycle is better than ATF and other oils that people tout, since it has a dispersion agent that keeps it from settling out in the tank when not moving.

You have to be careful about some of the things you read, as the biodiesel people are very aggressive about touting biodiesel, which with only 1% addition to regular diesel has much better lubricity. They often write horror stories about regular diesel, yet never explain why engines on regular diesel can see a 2 or 3 million miles without problems.

One last edit before I leave for work: This is an interesting report on additives. Southwest reasearch is reputable, but I don't know when this study was performed, so don't know whether it takes into account the newer processes for diesel de-sulfurizacion. It does not show a lot of improvement for 2-cycle, but they used it at 200:1.
http://www.dieselplace.com/forum/showthread.php?t=177728
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[baconsdozen]

I use a low ash 2 stroke oil at 50 to 1 max.There have been other studies on 2 stroke added to the newer diesel fuels and most seem to agree it can help reduce wear.I wasn't expecting any real improvement in power or economy but was pleasantly suprised with the decrease in noise.
There might be a greater build up of carbon in the cylinders and exhaust but so far I've had no problems.
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Thirty years selling imperial hand tools for old machinery(Now happily retired).

[Richard H]

I run my current A35 on standard unleaded, and I haven't had any problems with it, although I certainly don't drive it hard! My last A35 had a 'catalyst' in the tank and the previous owner warned me about using additive with the catalyst, so I just used standard unleaded in it. Again, no problems. My first A35 was run on 4 star until it was banned, then unleaded with Castrol Valvemaster.

The only effects these cars seemed to suffer was occasional running on (which interestingly was worst on the car that was run on Valvemaster). My Aunt's 1987 Mini is also run on Valvemaster, and she experiences quite serious run-on too
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Richard Hughes

[richardlw]

Runon is dangerous for the engine. Normally caused by carbon buildup on the head or piston crown. It can almost always be cleaned up with one or two tanks of fuel with Chevron Techron.
_________________
Richard's Cars - NEW **
Motor oil for Flat Tappet Engines
Transmission oil

[Jim.Walker]

An investigaton years ago by one of the big motor companies established that run-on, although often caused by carbon deposits, could be caused by such as a heater motor "running down" and acting as a generator. I think that a recommendation was also made to wait for a few seconds after coming to a stop before switching the engine off.
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Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then!

[47Jag]

A fast idling speed will cause run-on (over 750 RPM). In North America when the the early emission laws came in the manufacturers had a higher idling speed to get the correct emission readings Using carbs.) but that caused severe
run-on, so they fitted what they called anti dieseling solenoids. This was an electric plunger that held the idle speed at the correct emission level but dropped back when the ignition was switched off.

Art