Do I need petrol additive in an iron head A10?

[iansoady]

I'm picking up my new (to me) Golden Flash next week - a 1961 model which needs quite a lot of cosmetic fettling but has had some (I believe competent) engine work done on the bottom end.

Not having run a cast iron head for many years, what is the current view on needing additives (eg Castrol Valvemaster)? I remember when leaded was phased out there were all sorts of horror stories. I was running a Triumph Stag and a Norton Commando at the time (both alloy heads) and found there was absolutely no valve seat recession on either. However, the tests the FBHV did were, I understand, on an A series BMC engine with CI head and this did suffer.

What is the experience here?

[terryk]

An egg cup of diesel or recommended amount of upper cylinder lubricant or whatever valve name they give it every now and then is all you need to do. Dont worry too much if you dont put any in for a while cause some people dont use anything and it seems to be fine. I tend to put it in every few fills or so. Use the highest octane fuel to avoid pinging (pinking) use 98 if you can get it.

[a101960]

Ian

I do not think that you have anything to worry about. The main issue is weather it pinks under load, and unless you have HC pistons even this is unlikely to be a problem. If you search around 4 star leaded petrol is still available, but it is hard to find and expensive. I always used to use 4 star leaded petrol when the garage just down the road used to sell it. That garage stopped selling it about 18 months ago because it was such a slow moving item and it was not worth his while. Since I was forced into using unleaded I have noticed no difference. Unless you are intending to ride the bike like a boy racer then you should have no problem. Alternatively you could buy yourself a supply off Tetraboost, http://tetraboost.com/  but I am not convinced that you will need to do this. I do not know of anyone that has experienced valve seat problems. Also remember that when the A7 was introduced in the 1940's the only petrol available was "Pool petrol" which was vastly inferior to the petrol that we buy today. Unleaded petrol is rubbish, in the context of suitability for our older bikes and there are many people that say that it goes stale, well I leave my A10 laid up for the winter with a full tank, and do you know what? it always starts up when I get it out in the spring. Just fill up and enjoy the bike. All I add to my petrol is Redex.

John

[groily]

Can only speak for myself Ian but I haven't bothered with any additives/lead substitutes for years. I've used a product called XPCL (or something) as a top-end lubricant from time to time (bit like John's Redex) to help with bedding in new bits.
On the iron head front I run a scruffy s/arm Flash and a slightly better s/arm B, plus one 74 yr-old car. All bog-standard internals, which may be the secret. I checked the clearances on the A the other day, after about 10,000km, and one ex valve was a thou off where I'd set it. That was it. Time before, also fine. Same with the B (and the 4-wheeler). On various alloy-headed bikes, same experience again, despite the fact that not all seats of that era can claim, like a Rolls Royce, to be OK for lead-free.
I've had no problems in a good few miles, but I don't thrash the BSAs within an inch of their life. I suspect reasonable care on the ignition and carburation side is a big part of not having troubles that could be blamed on modern petrol. I'm also a believer in regular use. Like John, I've never had petrol 'go off', but I don't lay things up in winter, so I've probably never left a bike long enough.

[iansoady]

Many thanks all.

It's really valve seat recession I'm concerned about rather than the octane level as I can always use super unleaded if necessary. Mind you, the Venom I've just sold ran happily on regular unleaded despite having an 8.5:1 compression ratio.

Like a10160 I've never been troubled with petrol "going off" although I read loads of people apparently having this happen to them. Put the bike in the garage in November, drag it out in March and it starts first kick.

[a101960]

Use the highest octane fuel to avoid pinging (pinking) use 98 if you can get it.

In the UK Tesco sell 99 octane petrol which is what I use. However this petrol has 10% ethanol added to it. What this means in practical terms is that 1) it attracts water vapour, and 2) it can attack your paint. The over spray on the inside of my tank has been so affected, but crucially the outside of the tank has not because the lacquer has protected it. Some people have reported other problems such as deterioration of fuel lines, floats, and other plastic or rubber components. So far I have not.

John

[a101960]

Ian

Which area of the country are you based? I ask this only because the Wiltshire branch of the BSAOC club are having a camping weekend at Seend this weekend. Maybe you would like to pop down there. I am not into camping myself, but I shall be there  on Saturday.

John

[Stu55Flash]

I have 1951 Ferguson tractor and this debate comes up now and then on the forum. People are adamant that lead was not added until the late 60s early 70s. So anything before that is OK.  Petrol oxidizes hence goes off after a time. I have experienced problems starting with old petrol in a 2 stoke.

Stu

[A10Boy]

Is that the TE20? There's a forum for them is there??  

BTW, for what it costs, I usually use Castrol Valvemaster plus. Can't do any harm.

[Beezageezauk]

Ian,

I'm sure that you won't have a problem with valve seat recession but can I suggest that you ask the previous owner if the bike had hardened exhaust valve seats fitted when the engine was overhauled.

If it has then that will give you 100% peace of mind.  If you can't find out or if the answer is "No" then I wouldn't worry about it too much.  As the other guys have stated, there is generally not a problem but it wouldn't harm to treat the fuel to a drop of top end additive now and again.

Just on the off chance that it does suffer from valve seat recession at a later date it would be an easy enough problem to rectify.  

Beezageezauk.
 

[BSA_54A10]

It's really valve seat recession I'm concerned about rather than the octane level as I can always use super unleaded if necessary. Mind you, the Venom I've just sold ran happily on regular unleaded despite having an 8.5:1 compression ratio.

Well the short answer is no.

Valve seat recession is a bit of a myth.
It dose not become a problem for domestic cars & motorcycles.
It was a big problem in piston powered aircraft so unless you are doing 12,000 rpm @ 40,000ft with a leaned burn to compensate for the reduced oxygen content at that height, don't worry.

Like a lot of things, oponents of unleaded picked up on US Military air research ( initially ) then US & European civil avaitation tests and blindly applied them to all engines. Some car engine may suffer a little but they are liable to be junk bottom of the line throw away models. Every thing else is fine.
Did 400,000 + on about 6 or  SR 500's, no problems, know a pile of old Holden ( GM to some ) owners who d big miles in their old iron headed cars and none have ever had problems with recession.
Valves burning yes, regession no.

[Pete Gray]

I run my iron head A7 on unleaded with, when I can, the prescribed amount of Castrol Valvemaster on each fill.

No pinking or other issues but I have experienced petrol quality problems after one long winter layoff, the bike ran really badly, misfiring and spitting. I put fresh fuel in the tank ( in addition to what was probably 1/2 gallon left in there) and hey presto, all problems disappeared.