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What have you done today with your Austin Seven
My Pearl runs a 1 1/8 SU with a GG needle.  I only get something like 35 mpg, which I attribute to mostly driving around at nearer 40 mph rather than 30 mph to avoid antagonising the rest of the rat-race traffic behind.  Maybe 40 mpg would be possible if we could turn the motoring clock back and pootle along 1930's traffic free roads !
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I have mentioned before. My father used to keep close records and often ran the car dry to check mileage. Around 1950 two (by modern standards small) adults and two children in our RP travelled twice a year 200 miles each way to vist parents. Originally strove for 45 mph but found this too fatiguing on the winding, undulating, patched roads of the time so settled for 40 mph. Obtained consistent 50 mpg. A different silencer and larger tail pipe reduced to 40 mpg. In my use with SU and no attempt to optimise needle gave 38 mpg all conditons, regularly flat out.
My father was very considerate of machinery and did not apply more throttle then car would take. Although the air consumption is much the same, with a 4cyl this generally reduces fuel use. (The suction pulses are less severe)
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We attained an average of 35mpg 5 up, fully loaded with camping trailer last summer around France.

In the mountains we were down to almost single figures but evened out on the vast plain that Northern France is.

1” SU in an AN needle same internal spec. (and builder) as Hugh’s!

In my experience, mpg is more affected by driving style than any much else.
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I have always kept a note of how my Austins perform on long distance runs.  Most have been in the 31 saloon which has a 4.9 axle and a mildly tuned engine that has always run on a 1" or latterly 1 1/8"  SU with either AN or EB needle (ie Morris 1000 0r Mini 850)
My fuel consumption figures for the saloon are as follows:
Pennine Run 36.9 (first major run, carb not set up correctly), 43.9, 41.2, 44.6
Welsh Marches Trip 43.5
Lakeland/Cumbria Run 43.9, 41.4, 41.6
Borders/Scottish Trips 41.0, 46.6, 38.1, 36.6, 38.4, 39.9, 42.6, 39.8, 39.4,
Isle of Man Trips 45.5, 38.0, 43.3, 36.9
Coast to Coast 40.3

Looking at my notes, the single most important factor regarding fuel consumption appears to be how windy it is.
I always run on super unleaded.
The Ulster, with a similar spec engine to the saloon but with a 5.25 axle and somewhat lighter, returned 46.7mpg on a Cumbria Run including the return journey from Grange to Boltby in 2 hours.

I think this shows how a little bit of extra bhp pays dividends, especially with a 3 speed box and 4.9 axle.
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Given that, living near Bala, I seem to do an awful lot of scrambling up and down mountains mostly in third and sometimes in second, my RP saloon, on standard low compression head and Zenith carb, is doing between 34 and 36 mpg.

On a completely different tack, I met up with the Salop Yesteryear Motor Club at 'Yr Eagles' pub in Llanuwchlyn yesterday lunchtime by kind invitation from Nigel Coulter. A very interesting range of cars turned up including a V12 'E' Type, an Alvis 12/50, TD MG, Daimler Conquest Century and several more.

Here is a photo of Nigel's RP saloon cuddling a very original Rolls Royce 20/25 limousine in the pub car park:


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Hi All

Welded the bulkhead hoop to the scuttle frame of my special.  It is 1" angle iron and was quite difficult to bend without incurring lots of twist and a painful burn't hand (cherry red steel doesn't cool quite as quickly as I had thought!). The uprights are welded onto side rails which are, in turn, bolted to the chassis cross rails.

 I plan a 3mm bendy ply - 12mm ply - 3mm bendy ply sandwich with lots of large diameter holes drilled into the 12mm ply. All topped off with a fabric finish. Hence the angle iron. The ply sandwich will fit nicely into the angle and can be attached by screws through the back of the steel.

Welcome any comments.  

Should I start a new thread on the build rather than this one?

Cheers

Howard


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Hi Howard

18 mm of plywood, + padding + fabric, even with large dia holes in it will be
quite a lot heavier than an alloy construction.

I have an angle iron bulkhead like yours but the rest
of my GE Cup has 16mm ply bulkheads, 1” ash stringers
And 8 mm ply on the box section sills. Outer skin all
16 or 18 swg aluminium. Full length Wings are also aluminium .
The 4 wings weighed 1kg!!!

What type of special are you making ,
? Like a Cambridge or similar? Flat tail or pointed tail?

I’d go for a new thread of your own.

I’ve had 45,000 views in one year!!!!!
By 50,000 I hope to report on going places in it....

Regards

Bill G

Aka AllAlloyCup
Based near the Scottish Border,
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It is ever so easy to over engineer car bodies.   When I acquired "Alice" the bonnet top was made from ali over an oak 2" x 1" frame, three cross members and two stringers, as I recall.

None of which is required, the bonnet top is self supporting.   And so it went on.

One of my favourite materials is 1.5mm birch ply,I have used it to give the rear corners extra strength under the ali skin, over a laminated ash 1" x 1" frame, panelled with 3mm ply on the inside to carry the weight of the fuel tank hanging off the back.

If the chassis had had a Ruby style tank then a 1.5mm ply, or ali skin would be all that is needed.

Floors also are usually over-done.   Mine are 3mm ply - if the propshaft tunnel has a ledge on it, and there is a bit of softwood level with the chassis on the outriggers then very little of the floor is unsupported so you need nothing thicker.
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Thanks Bill and Simon

Yes I understand the over-engineering bit. My first special had an ash frame with an aluminium skin, aluminium wings and topped the scales at about 450kg even as a long wheelbase. But I fancy doing something different with this.

I'm aiming for a car suitable for vintage trials but one that I can also use on the road and will have a period look.  The "shape" will be similar to the infamous Cox tourer as shown in the current source book (I believe the car will be left out of the forthcoming reprint). So its a boat tail Bill.

The idea behind the ply sandwich came from Gordon England construction.  Rather than use ash between the ply I'm using very sparse ply.  The body will sit on the subframe and I'm hoping it will not need any bulkheads apart from the one already in place and one that will support the rear of the front mounted tank and dashboard.  Although I will be putting doors in the car and they may require some support.

Again taking a cue from Gordon England I'm hoping that the body will be totally separate from the running gear including the dash.  I can then complete the mechanics of the car without fear of damage to the fabric body.

Taking on board your comments Simon I may cut back on the ply thickness.  

I think I'll hang fire on a separate thread just at thee minute and see how things go.

Cheers

Howard
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I agree with comments about over engineering and this may help, my old special was built with a 1.6mm alloy floor 1.2mm firewall/bulkhead, the seat back was 12mm ply, the body sides 6mm ply with 12mm doublers along the open cockpit edges, it was fabric covered, I used traditional wadding under the hooding vinyl to avoid the over stuffed look you get using thin foam underlay. I have one or two construction pictures which I will endeavour to find for you if that will be of assistance, the car was light and survived 30 years of hard used before I rolled it. 

   
Black Art Enthusiast
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