mpg

[phurn]

I've noticed a few people on here mention that they get much more mpg than I do.... what should I be expecting in terms of mpg from a 1098? I'm currently getting about 25 to the gallon.... which seems a lot lower than some others on here, I checked my plugs when I did my gasket and they looked healthy enough, no signs of rich running, and I haven't messed with the carb since, I don't exactly drive it gently, but I don't drive it hard enough to warren such a big change in mpg compared to some figures mentioned.

Is it possible my engine was unwell when I baught it, thus had been set up in such a way to keep it moving? So that now its fine te carb requires adjustment, I have noticed the odd cloud of greenish smoke behind me when I drive along. Not a lot..... just a tiny bit. I noticed my head wasn't exactly bolted down evenly... lucky me the head didn't warp.

[rayofleamington]

When I was using mine for local journeys around town and commuting in traffic, I was getting less than 30mpg.
In winter you'll get a reduction of mpg - not just from more time on choke but also the engine drag is much much higher with cold oil after starting so the first 3 to 6 miles the oil hasn't reached full temperature.

The good mpg figures I've seen are what you can get on a long run on clear road with the mixture adjusted well. If you turn your mixture by a couple of flats leaner and the car runs just as well, then you'll get slightly better mpg. If you weaken it too far you'll get white discolouration on the plugs and/or missfires.
The standard setting for mixture is 12 flats from the top - to check where yours is, you need to count how much it can be turned (screwed in) to reach the end. Be careful doing this as counting correctly you will be able to get back to where it was.
Also worth checking is whether the needle has got the circlip in the wrong groove.

[phurn]

I see, I know what I'm asking is Abit like how long is a length of string, as it depends entirely on driving style and conditions, I barely have to use choke tbh, and certainly for no more than 3-4 seconds when starting, then I can push it right in and away I go. Even in the cold weather. I have noticed that my throttle return spring on the carb is a very long string attached to the bodywork via a cable tie! I'm quite sure it didn't leave the factory like that.... though as it works fine and pulls the throttle completely back to its original condition I can't see this affecting much?

[ASL642]

I think you may be running a bit rich. The car should need to use the choke when starting for about the first mile of the journey. Everybody gets a different mpg - it also depends on the strength of the right foot!

[phurn]

Yeah I know that, that's why unexpected mine to be slightly lower as I'm not all that gentle, and I really.don't struggle to keep up with modern traffic but I'm still limited to 30 like everyone else.... if I do use my choke I can almost see my petrol gauge move! =[

[rayofleamington]

if you hardly need to use the choke in winter, that's a big clue that you're running rich.

[dalebrignall]

on a long run i get about 45mpg about 30 to 35 round town .

[MarkyB]

Another vote for running rich.
I'd say put at least 30 psi in the tyres, don't carry around spare batteries, cylinder heads etc. and read the road ahead such that you aren't accelerating when you will have to be braking any moment.

[simmitc]

You can also check the petrol pipes and pump for leaks (and even the tank!) and also check the float level - if it's set too high then there will be a loss of fuel from the carb. General tuning is important, so check valve gaps, and ignition points and timing.

[phurn]

I do ,have a spare radiator and battery in the boot!

[chrisryder]

I do ,have a spare radiator

we took a spare rad to france with us, but that was coz the one in there was dribbling!

i found it's a lot easier to chuck a bottle of rad-weld in there, then, short of a housebrick going through the core, it'll seal itself up!

[moggyadventurer]

Hi

Yes I would agree your mpg is quite low. Some good advice already been given regarding tuning. Make sure your brakes are not sticking. You'll be amazed by the drag factor. Tyres 145x14 (28-30psi) 155x14 (32-34psi). Would you say your engine has good compression?

I can remember being a bit heavy footed when younger, at getting about 32mpg. However if you keep it at 50, 40mpg is possible. My daily commute is 64miles and I get a minimum 44mpg.

With fuel prices as they are, I can understand your frustration.

[Edward.21]

try putting some redex or other injector cleaner in i got an extra 3-5 mpg just for doing that

[bmcecosse]

Since there is no 'injector' - that would be a waste of money!
You do need to optimise the engine settings - both ignition timing and mixture - but 30 mpg is about all you can hope for in 'about town' running with cold starts. Some Minor speedos are ~ 8% fast - which can make the fuel consumption appear rather better than it really is!

[phurn]

Since I've just done my head gasket id say I have very good compression! I do.doubt my carb is set up right tbh.alp the screws around the throttle linkage are screwed out to their maximum, so they have no effect what so over, which I figure can't be right most of my driving is done on a 26 mile round trip to work and back at weekends, all on minor a roads at about 35-40mph with very few stops once I've gotten over the a5 anyway =\ but that trip seems to use about a quarter of a tank!

[simmitc]

screws around the throttle linkage are screwed out to their maximum

One affects the idle speed, the other allows the use of the choke to increase the idle speed. Neither affect the mixture. As they are both right out, they won't be causing a fast idle (another cause of increased fuel consumption if idling a lot in traffic). However, I would not expect them to both be right out, so I suggest a through tune-up and so how things go.

[phurn]

Weird, since I've done my head, ticker does seem to be higher than it was! I might be imagining it though....

[chrisryder]

screws around the throttle linkage are screwed out to their maximum

the screws, one on the throttle linkage, and one of the carb linkage, only serve to clamp the cables. so they wouldn't affect your tuning.

there is a little screw on the throttle linkage that is pushed slightly by the 'cam' on the carb linkage. that increases the tickover slightly when the choke is out. ideally when the choke is fully in, you want the screw on the throttle linkage to be not quite touching it. there is another screw which is bigger, and seen from above the carb, which screws directly into the carb body. that governs the tickover speed when the choke is fully in.

as for richness, that is controlled by the large brass nut underneath the carb.

this is all true for a standard minor carb though. i've you've got a HIF, it'll be different!

[xpress]

Getting 24 MPG city, need choke out for a mile or two when nippy cold so mix should be ok? Timing too early?

[phurn]

for city driving thats good, mines more a combined cycle, with good extented juants at 50-60. so i was hoping for another 5-10 miles out of it.