Miles Per Gallon

[AlanBartlett]

What is the miles per gallon for my car? Or the 8hp engine rather, as I think currently I'm getting 10 to 12 miles out of one gallon. I thought I heard somewhere its about 30 miles to the gallon?

[Keith Andrews]

Club Economy Runs on Bradfords run Nz are about 33 to 38 mpg. and similar milage when 2 bradfords are racing on the open road.
Yes Bradford racing is a highly tactial sport...like choosing. timing the right times to pull over to let trafic past
And great similarities with 200 mph NASCAR racing, where even 100 yds takes alot to catch up, and using momentum on lines taken on cnrs...

I digress..
These old engines are very low compression, designed (timiong curves.cam profiles, combustion chambers)for the old non leaded pool fuels of around 65 /75 octane...put modern 91 one in with a lower SG and they just dont perform as they did when produced.

In saying that, our economy runs ( go to www.jowettnz.sytes.net left side nth branch events 2007 and back are the milages of jowetts) produce far better results, even on very worn engines, and most still have factory jetting.

fixing Worn butterfly bushes in the carb makes a huge diff
Cam timing setup correct
fixing play in dizzy and getting timing right
are all critical to good milage, even if the engine is worn with very low compression

If all the above is ok, dropping fuel octane has a +ve effect on power and economy....10 to 15% of A1 avaiation fuel in 91 octane drops octane to low to mid 70s
Note: A1 IS different to your normal kero/parrafin, do not consider or use kero u will damage the engine if it is not working hard all the time.

[george garside]

Alan
for what its worth the Motor tested akestrel in Feb '33 (4speed box) and found that 'on covering 37 miles of hilly roads on a rough daythe tank was found to be emptied by just one gallon.'


Light car got 34mpg out of a '34 kestrel undr'arduos conditions' which included climbing the notorious hill Park Rash in north yorks with gradient of 1 in 3 to 1 in 4!

Autocar got 35 - 38 mpg out of a 1938 '8'

Autocar quoted 40mpg for 1930 long saloon.

So new but driven hard under road test conditions it looks like high 30s. I usually got around 40 out of various eights driving near flat out most of time but not accelerating hard in the gears & changing up early to take full advantage of the torque available.


I would think that 'around 30' would be reasonable to expect in todays driving conditions where 'hard acceleration' ! is required to keep up with modern traffic & all available power is repeatedly used in stop start driving in towns.

It would be interesting to know what other people are getting out of 7's & 8's under todays conditions.

george

[AlanBartlett]

My run to the beach of an evening is a total of 28miles, 13.7 there and 13.7 back(Google Map), and I put in 10 pounds worth of fuel which is at the moment, 8.34 litres. And I use that in the one journey.

The journey there is fairly a flat with a short, 10% hill up which I tackle in 3rd, and on the journey back is a long 10%, which I go as far as I can go up in 4th then to 3rd then a sharp change down to 2nd and this is about 100yards left of the hill.

Would this acount for my fuel usage? Because Ive worked it out that £5 of fuel a lil under a gallon.

It doesnt make sense as ive made, 60mile trips on about the same amount of fuel, how does that work?

As Keith was saying about warn bushes my throttle circle flappy thing is infact a little warn, ive noticed when they close to let no fuel in the whole thing moves to the side clamp the circle shut. And Ive notice on half throttle it back fires lots and and splutters, Because Ive been mostly using it hard to keep a good pace, but I should get my speedo cable back today so I'll make the same journey again tonite keeping at the same speed to see how it differs the results.

[Keith Andrews]

And Ive notice on half throttle it back fires lots and and splutters

And when u back off to slow down using engiune brake, it sort of pops thru the exhaust pipe?
Vaccuum leak, worn butterfly bushes..
And cant get conistant idle mixture right?
And cant get a real slow putt..putt even idle?
Worn butterfly bushes...

If u want to check the distance between 2 points, even the local shop and home...use google maps, u will be amazed how accruate it is...VERY
That is a good way to check your speedo/odometer.

We have check several distances in the wifes corrolla, the subaru and camaro...in miles and kms...every time they are spot on
The bradford reads about 11% high
AND the Camaro speedo has been checked against a kind cop with a radar on the side of the road..no wasnt pulled over, I stopped and asked him if he would check several speeds as I came down the road.

But forget google estimate travel times They are 'Bradford Times' when travelling in the Camaro...

[george garside]

Hi Allan

have you changed or adjusted the carb and/or ignition timing or removed & refitted any of induction pipe, carb; distributor between when it was doing 30mpg & the apparent reduction to about 15mpg. If so check for air leeks carb to induction ppipe & insuction ppipe to pots. If distributor changed recheck timing, points gap and make sure that the advance/retard springs are not broken & that the mechanism opporates smoothly. Also check for fuel leeks all the way from the tank as fuel may only leek when being pumped 'at speed' & not be obvious. Have you noticed any reduction in power along with reduced fuel consumption if so are both cylinders firing evenly & compression (either with compresion guage or by feel on starting handle) the same - if not check tappet adjustment if ok - it may be a burnt valve. over retarded ignition &/or week mixture are most likely causes. If advance mechanism in dizzy not working it will stay retarded - this can be checked on flywheel with strobe.

If you havn't disturbed or adjusted anything then the worn throttle spindle is irrelevent as it uded to do 30 mpg & now does 15 with same worn spindle. Thats not to say that a better one would not greatly improve overall running, just that its not particularly relevent to the apparent drop in consumption.

george

[Keith Andrews]

I mention octanes/compression ratios above
On the bradford engine and assume the a very similar situation on pre war, accurate factory settings timing valves , as george mentions, will give best economy regardles of fuel used.

Warn butterfly bushes have a dramatic effect...I have used several carbs of varing degrees of wear, and fully reconded one.

[AlanBartlett]

Right then, on checking compression with the handle it seems better than before, but I do think my petrol pump is leaking it seems wet.

After 7 days of 30mile round trips, I have discovered the following results. The steering has gotten worse, and on close inspection and strip down, the tie bar on one end has lost most of its thread which looks to be caused by the split pin moving around in the hole. And the steering box's chassis support has snapped, luckily I think it happened today in town, so I dont think Ive driven very far with it broken. And the third and final thing is I think I have another head gasket on the way out as the water seems to bubble around and buble out of the raditor when moving at speed. And finally the petrol consumption problem which in the above I think Ive found the conclusion.


So now, a couple weeks of rest and repair are in order for the old girl.

[Tony Fearn]

On the way up to Crieff NJR at the overnight stop in Galashiels I just happened to lift the bonnet on the 'Flying Fox' whilst the engine was running.

Now this is a bit spooky, but at about 3 am on the day I was setting off, whilst in bed, I remembered that although I reckoned I had put in the car enough spares for every eventuality, I' d forgotten to include a selection of fibre washers, so I included a few different sizes.

Guess what was the only spare I needed on the 620 mile round trip.

On lifting the bonnet I noticed that both of the two hexagonal brass pump valve covers were weeping petrol. One tightened up with a spanner, but the other didn't, so I replaced the fibre washer under it and the top of the pump stayed dry on re-starting the engine.

So perhaps a check on the simpler things first could pay dividends.

Also a twist or two of PTFE tape around petrol pump/carb connections before tightening may stop un-wanted leaks.

Tony.

[AlanBartlett]

Today i emptied my tank and made fresh markings on my bamboo stick of the gallons, as this doesnt go all the way down to the bottom I also worked out how much I had left at the end of my stick. I filled it up to one gallon on my stick, went on a 30mile run. The beach run. Got back and it had used half of my marking for the gallon, so it used half a gallon on 30 miles, which now seems incredibly good, maybe even too good to be true.

[Keith Andrews]

saounds good, but a "stick"
Either Full right up at a gas station, till the pump cuts out....do your run, return to the same pump, and refull till it cuts out
OR
Run till the tank is MT, have a 5 or 10L container, refill the tank, and run till MT again.

[george garside]

I used to use a 2 pint oil tin with a pipe attached to the screw cap which in turn was connected to a legth of plastic petrol pipe. the can was attached upside down with elastic to the nearside window frame (window open) , the reason for upside down being that the cap under the can formed a sump so all fuel was used.
The drill was to disconnect pipe from petrol pump & run carb dry. then attach pipe from test tankwith a measured pint of petrol in it. then proceed untill carb again ran dry. It gave a vry accurate measurement & was particularly interesting if tried on different terrrain, stop start running etc. The only problem is running out of juice in an aawkward place but it was normally possible to pull in with the last splutter so to speak.
might not be sensible to do on todays roaads!

george