Unleaded question

Post by **paulg** » Fri Aug 08, 2003 11:51 am

When I had my head unleaded the machine shop did 3 things:
1) hardened exhaust seats
2) ground off the "peak" in the combustion chamber. Apparently this can get very hot (ie glow) and can cause run on.
3) skimmed the head (basically because it seemed a good thing to do! but also does compensate a little for the lowering of the compression ratios caused by the peak being removed).
Result: Compression when tested about 11.5 bars. Did a retime to standard as its easy when the head is off (better access to the distributor). Fooled around with the mixture too. Car runs fine, don't really notice any power loss although I suspect the top speed is a bit slower. No run on, no pinking. Can't really tell on consumption (odo stuck at 23500). I use straight unleaded.
Note that since then it has overheated (child did not check water on long run and rad was failing to cool properly), been reskimmed and recently had an exhaust valve burn out.
As I have had an exhaust valve burn out on every A series I have owned I doubt that this is due to the unleaded. Only difference was the Minor burnt no3 before the conversion and no 2 after. The Minis burnt always no 3.

Post by **Willie** » Sat Aug 09, 2003 8:41 am

I think you will have very few problems when you start
using unleaded fuel. The basic unleaded is 95 octane
if it gives you chronic pinking then you can try the next
grade(and price) up. The thing to remember is that
setting the timing according to the manual is a STARTING
point. You then adjust the timing to suit your particular
car because there are many variables, like your style of
driving, how fast the tick-over is(running on) etc etc.
I have set mine up to suit the basic unleaded and then
use the next grade up to give me a bit of a safety margin
in the 'Pinking' department. It still runs nicely.

Post by **Chris Morley** » Sat Aug 09, 2003 2:56 pm

I can back up Willie's comments. I use 97 octane super unleaded and I adjust the idling speed according to the season. I don't get pinking and rarely suffer from significant over-run. (standard 1098cc, original head). Performance may be slightly impaired compared to 98 octane 4 star -although Shell Optimax should be the same rating as 4 star.

Post by **Shmickle** » Sat Aug 09, 2003 3:03 pm

Is pinking that thing when the the engine is strugaling, like on a very low hill, and you have to change down to build up your 'umph' again??? If it is, I love it when that happens. Obviously not when i'm dving, cause I can't drive.

Post by **Chris Morley** » Sat Aug 09, 2003 3:51 pm

No, that's caused by a lack of bhp and torque....

Post by **Cam** » Sat Aug 09, 2003 5:33 pm

Pinking is a noise like 'tinkling glass' that can occur when the engine is under load and / or you are using low octane fuel.

Personally I would not use anything lower than 97 octane in any of my cars (all old!) as I think it's worth the extra money for piece of mind (it is to me anyway).

I would either use optimax, Castrol valvemaster plus or both (like me!)

Post by **grainger** » Sun Aug 10, 2003 12:22 am

yeah me too, optimax is great, its very hilly round here and it gives it that extra bit of whatever to get up in 3rd instead of 2nd. i have a standard 1098 leaded head in a traveller, and ive done over 6000 in 6 months.

kevin said about adjusting the timing according to the fuel. i think mine is now very advanced, i use the octane boosted valvemaster too , just turn the advance up a bit each time you go out and see what it sounds like ... but i cant be sure exactly until i get a light.

optimax and valvemaster also clean the engine out ... i presume they help to stop it 'coking up' ? whatever that is

because thats a very common cause of run on, which mine doesnt do much now - my spark plugs are generally clean. and i get good mileage out of it, everywheres a long way away round here.

hey cam, owt going on in stoke either this wednesday 13 or next monday 18th ?

cheers
grainger

Post by **Kevin** » Sun Aug 10, 2003 9:19 am

kevin said about adjusting the timing according to the fuel

I think that was Willie, but just a thought on timing I wondered what was / is the average setting that is being used on leaded or unleaded heads, and does petrol type affect it very much.

Post by **Chris** » Sun Aug 10, 2003 4:35 pm

hi all,
My 1098 has got an unleaded head which was fitted before I bought it, and I try to run on optimax as often as I can. Havn't had any problems with it at all though.

I did a long trip a couple of weeks ago up to exmoor and back and had no problems at all. The car managed a lot better than I did, I took me 3 1/2 hours to get there when it should have been about 2 1/2 to 3 hours - it was my first long trip and I lost count as to how often I got lost.

That was about the only time I used cheapy supermarket fuel - well I was practically running on fumes and it was the first fuel station I came across coming back from exmoor (although I did have still a spare gallon of optimax in a can).

- I also saw a light blue saloon just south of Tiverton, was that anyone from here?

Cheers,
Chris

Post by **paulg** » Mon Aug 11, 2003 2:31 pm

"Who did the work on your head? was it local? I notice you're in !Hants."
A company near Portsmouth on the old airport. It may have been taken over or renamed because last time I was there I saw the "Boarhunt" garages sign.
I always use supermarket 95 octane petrol ... seems to run fine. So did my Golf using supermarket diesel. But....
I am always surprised how dirty the head is when taken off. When it blew a head gasket after 300 miles (overheated) the head was pmuch cokier than I expected.

Post by **Cam** » Mon Aug 11, 2003 6:58 pm

Grainger,
Yes!! we have the local potteries branch meeting on the 3rd monday of every month (which this time is the 18th!!) trouble is that it starts at 8pm and goes on until about 11pm ish. If you are going to be in Stoke at that time, give me a shout and we can arrange to meet up!

With regard to the fuel, you should really adjust the timing if you are using LOWER octane fuel than before. If you are using higher octane then you won't have any problems. BUT if you want the maximum performance and efficiency out of the engine then adjust the timing accordingly. But you won't damage anything if you don't.