Author Topic: 1/3 Scale Austin Seven  (Read 5927 times)

Offline Austin Seven

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1/3 Scale Austin Seven
« on: September 17, 2023, 09:44:42 PM »
Hello All. Great web site. Some fantastic work.
I've been building a 1/3 scale 1933 Austin Seven engine for many, many, many...... years now.
I'll post some pictures / videos when I sort them out.

Offline A7er

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Re: 1/3 Scale Austin Seven
« Reply #1 on: September 17, 2023, 11:23:07 PM »
Oooo! I'm looking forward to this. I have a full size 1933 Austin Seven, and hopes of building a 1/3rd size engine. One day.

Offline Dave Otto

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Re: 1/3 Scale Austin Seven
« Reply #2 on: September 18, 2023, 12:01:35 AM »
Welcome to MEM!

Dave

Online Jo

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Re: 1/3 Scale Austin Seven
« Reply #3 on: September 18, 2023, 06:51:28 AM »
 :hi: Rob,

There are a lot of fans of "Chummy" on the forum. We will all be interested to see your work  :)

Jo

P.S. My friend has a 1933 Box Saloon, affectionately known as Hilda   :Love:
Enjoyment is more important than achievement.

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #4 on: September 19, 2023, 08:51:10 PM »
I've taken the head off to fix a small leak.

Online Vixen

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Re: 1/3 Scale Austin Seven
« Reply #5 on: September 19, 2023, 09:20:08 PM »
That little engine is a jewel, Lots of historic build photos please.

Mike
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Sometimes, it can be a long and winding road

Offline Admiral_dk

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Re: 1/3 Scale Austin Seven
« Reply #6 on: September 19, 2023, 09:26:19 PM »
When I first saw the picture - I was in doubt about it being a model .... until I spotted the Yuasa Battery in the background  :praise2:

Per           :cheers:

Offline ozzie46

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Re: 1/3 Scale Austin Seven
« Reply #7 on: September 19, 2023, 10:12:02 PM »
Now that is something to behold.

Ron

Offline pgp001

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Re: 1/3 Scale Austin Seven
« Reply #8 on: September 19, 2023, 10:58:08 PM »
I see it has the 4 bladed export fan fitted. Must be from a hot climate  :)

Offline A7er

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Re: 1/3 Scale Austin Seven
« Reply #9 on: September 20, 2023, 08:48:27 AM »
I think that is the best model engine I have seen. My 1930 A7 special has a four blade fan because the radiator is shortened. It also has a semi-sidedraught S.U, similar to yours, but at an angle.
More pics please!

Offline Chipswitheverything

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Re: 1/3 Scale Austin Seven
« Reply #10 on: September 20, 2023, 08:52:27 AM »
This is a beautiful piece of model engineering.  Will be interested to see more pictures and information, as I'm sure will many others of the forum members.  Dave

Offline Tonyr

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Re: 1/3 Scale Austin Seven
« Reply #11 on: September 20, 2023, 09:09:44 AM »
Fantastic model, well done.
Tony

Online Jo

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Re: 1/3 Scale Austin Seven
« Reply #12 on: September 20, 2023, 10:26:13 AM »
 8) Can we see more of it?

Jo
Enjoyment is more important than achievement.

Offline Roger B

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Re: 1/3 Scale Austin Seven
« Reply #13 on: September 20, 2023, 05:00:29 PM »
Excellent  :praise2: Love to see more  :ThumbsUp:
Best regards

Roger

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #14 on: September 20, 2023, 06:43:48 PM »
I've made the radiator core which took a lot of experimentation. The engine gets very hot very quickly, so I've put an electric water pump on it. I'm hoping once it's run in I can remove it. Oh yes, and the four blade fan helps.

Offline bent

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Re: 1/3 Scale Austin Seven
« Reply #15 on: September 21, 2023, 05:25:25 PM »
Wow, that looks neat!

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #16 on: September 21, 2023, 06:57:49 PM »
Head and rad back on.

Online Art K

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Re: 1/3 Scale Austin Seven
« Reply #17 on: September 23, 2023, 02:03:13 AM »
I just wanted to chime in here and say that engine is a beautiful machine!
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline petertha

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Re: 1/3 Scale Austin Seven
« Reply #18 on: September 23, 2023, 07:34:25 AM »
Very nice. I look forward to any build pictures. Can you provide an overview of the ignition system?

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #19 on: September 26, 2023, 07:13:16 PM »
Hi petertha,

The ignition system is by 4 magnets on a disc in the distributor acting on a hall effect sensor. That is connected to a control module from Minimag Co. I've added a pencil to get scale.

Offline RReid

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Re: 1/3 Scale Austin Seven
« Reply #20 on: September 26, 2023, 08:06:03 PM »
That's a lovely and authentic looking engine; very well done! The "SU" carb looks the part too! :ThumbsUp: :ThumbsUp:
Regards,
Ron

Offline Admiral_dk

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Re: 1/3 Scale Austin Seven
« Reply #21 on: September 27, 2023, 07:19:46 AM »
Great details  :praise2:

It kind of looks like it has been running for a while - when I look at the Distributer ....

Per        :cheers:

Offline A7er

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Re: 1/3 Scale Austin Seven
« Reply #22 on: September 27, 2023, 09:35:22 AM »
I can just make out a horizontal line on the side of the cylinder head. Is this a join where the head was cast as two parts, or a (very neat!) casting line?
The detail in this engine is amazing. The LUCAS name on the dynamo is perfect. If you post a video on utube please let us know.

Offline pgp001

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Re: 1/3 Scale Austin Seven
« Reply #23 on: September 27, 2023, 01:07:43 PM »
Having built a few full size A7 engines for my RTC Special in the past, I can honestly say that this is one of the nicest and true to prototype model engines I have seen for a long time.
In fact it is right up there with the ones Mike Sayers produces in my opinion.

Phil

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #24 on: October 08, 2023, 08:49:08 AM »
The head is made from two bits of plate with the waterways machined and then bonded together with dowels. The outside is then machined.
Here are some pictures of the build.

Offline michelko

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Re: 1/3 Scale Austin Seven
« Reply #25 on: October 08, 2023, 10:33:13 AM »
So beautyfull parts :cheers:

Offline Admiral_dk

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Re: 1/3 Scale Austin Seven
« Reply #26 on: October 08, 2023, 05:14:56 PM »
Wauh - it's getting better and better  :praise2:

Per

Offline wagnmkr

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Re: 1/3 Scale Austin Seven
« Reply #27 on: October 08, 2023, 05:24:56 PM »
All I can say is WOW!  Incredible workmanship!
I was cut out to be rich ... but ... I was sewn up all wrong!

Offline petertha

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Re: 1/3 Scale Austin Seven
« Reply #28 on: October 08, 2023, 09:18:08 PM »
Beautiful parts! Can you tell us a bit about the crankshaft? Assume its from solid? - material, turning operations, grinding/lapping... Did you have any post-machining distortion issues to contend with?

Offline pgp001

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Re: 1/3 Scale Austin Seven
« Reply #29 on: October 09, 2023, 10:29:59 AM »
It looks like it might be based on a Phoenix crankshaft ?

Offline Mike R

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Re: 1/3 Scale Austin Seven
« Reply #30 on: October 09, 2023, 04:17:54 PM »
Also, what is the coating or treatment done on the rods?  It looks great (as does the rest of the engine)!

Offline nj111

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Re: 1/3 Scale Austin Seven
« Reply #31 on: October 10, 2023, 09:01:36 AM »
Wow, this is truly exceptional!  Would love to see more detail of how you went about machining various items. Well done !
Nick

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #32 on: October 10, 2023, 06:02:34 PM »
Thanks all.
The crankshaft is machined from 50mm EN16 round bar. I sliced the sides off to create a flat plate, then machined most of it in the milling machine. I have tried to machine cranks before only in the lathe and have spent many an hour digging the bent crank out of the ceiling after it left the lathe in a hurry.
The finish on both rods and crank is from shot blasting.
If it looks good leave it, if it doesn't paint it or better still shot blast it.

The first picture is the crank being machined, the second is the distributor to get a sense of the scale.

Offline Roger B

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Re: 1/3 Scale Austin Seven
« Reply #33 on: October 10, 2023, 06:13:38 PM »
Excellent  :praise2: 
Best regards

Roger

Offline John Roberts

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Re: 1/3 Scale Austin Seven
« Reply #34 on: October 10, 2023, 07:10:06 PM »
Incredible machining. How did you make the crankcases? They look like really good castings. Lost wax?
  I have a friend who has had Austin 7's for over 50 years. I can't wait to show him your photos. Please carry on showing us more pictures!!!

Offline Admiral_dk

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Re: 1/3 Scale Austin Seven
« Reply #35 on: October 10, 2023, 09:19:36 PM »
Quote
If it looks good leave it, if it doesn't paint it or better still shot blast it.

 :lolb:   :lolb:

But I do agree that it looks really good after you have 'Blasted it'  :praise2:

Oh - what kind off shot blast material, Gun and preasure ?

Per           :cheers:

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #36 on: October 14, 2023, 09:50:39 PM »
The shotblast is small like an air brush using aluminium oxide.
Here are a some more pictures.

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #37 on: October 17, 2023, 07:07:15 PM »
Hi All.
Has anyone had experience of very small, high torque electric motors that can be used as a starter motor?
I have very little package space. 22mm diameter x 40mm long. I've tried quite a few, but all have gone up in smoke.

Offline Admiral_dk

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Re: 1/3 Scale Austin Seven
« Reply #38 on: October 17, 2023, 08:21:26 PM »
I would expect that you need at least one, if not two, more gear stages to reduce the RPM's and increase the Torque enough ....  :old:

How that is going to fit into the space available to look right - is a bit unknown ....
This kind of brings us to - that not all parts scale equally well  :(

Best wishes

Per      :cheers:

Offline uuu

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Re: 1/3 Scale Austin Seven
« Reply #39 on: October 17, 2023, 09:02:55 PM »
Tiny geared motors do seem to exist: https://www.ebay.co.uk/itm/GA16-050-DC-12V-33-340RPM-Gear-Box-Micro-DC-Geared-Motor-DIY-Car-Robot-/225658570241

Not that I have any experience here - just sniffing around the problem.

Wilf

Offline crueby

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Re: 1/3 Scale Austin Seven
« Reply #40 on: October 17, 2023, 09:41:58 PM »
What speed does the output shaft of the motor have to go? And do you  have an idea of the torque needed? I've  done lots of looking around at gearmotors for models, those numbers plus the sizes you gave would help a lot in narrowing it down.


Chris

Offline Admiral_dk

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Re: 1/3 Scale Austin Seven
« Reply #41 on: October 18, 2023, 09:20:00 AM »
Interesting suggestions Wilf  :ThumbsUp:
.... and I see that there is a World of different ones too  :o

My best guess is that the Crankshaft should be turned somewhere between 120 to 240 RPM - and I do not know what the Final Gearing to the Clutch-Basket is - but I'm sure that 'Austin Seven' can help us with that info  ;)

Per         :cheers:

Online Vixen

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Re: 1/3 Scale Austin Seven
« Reply #42 on: October 18, 2023, 12:02:32 PM »
Hello A7

Most small i/c engines have a very fast tick-over (2000 to 3000 RPM ish)  compared to their full size counterparts. I have always found a small engine will start better when using a cordless drill in the high speed range rather than the higher torque, low speed range. For your Austin Seven, I would aim for a crank shaft speed of at least 300 to 400 RPM, perhaps higher. You will definitely need a one-way clutch to disengage the starter motor after the engine fires.

Mike   :thinking:
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Online ddmckee54

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Re: 1/3 Scale Austin Seven
« Reply #43 on: October 18, 2023, 03:36:21 PM »
You'll find lots of gearmotors, but your space limitations are a real killer.  You can get small-ish planetary gearmotors that will give you around a 300 rpm output, that would probably have the torque needed to turn over your engine, but those guys are typically 25mm in diameter and I think the length is 60-75mm?

The only gearmotors that I can think of that will fit in you available space are the little N20 gearmotors.  They are tiny, only about 10-12mm thick, 15-20mm wide, and maybe 30mm long.  (They are definitely NOT round, and in no way resemble a starter motor.)  Those are available in a variety of output rpm's, and motor voltages, but I doubt that they've got the oomph to turn your motor over.  They've only got a stall current of about 0.6A.  If you were making a non-working engine with no compression, they'd work fine.

Don

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #44 on: October 18, 2023, 04:15:47 PM »
Many thanks to all for the replies.
I start the engine at the moment with an electric drill set to fast as per Mike's comment. That's about 1600rpm (no load). The flywheel has 87 teeth, the starter gear has 14. That would require a starter speed of about 10000 rpm.
By the time I've finished with this, I think the starter motor may end up bigger than the engine!

I've attached a picture of the dynamo (3 phase alternator with three phase bridge rectifier). That took a long time to design as I wanted a 6v system with about 0.5 - 1 amp.

Rob

Online Vixen

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Re: 1/3 Scale Austin Seven
« Reply #45 on: October 18, 2023, 04:39:03 PM »
Hello Rob,

Some of the ready-made multi-cylinder engines coming out of China, are now using small diameter, brushless motors powered by a 12v to 24v Lithium battery pack (which can provide infinite amounts of current). The brushless motor is grossly overdriven (torque is proportional to current) but only for a few seconds; so overheating is not a problem. You cannot overdrive a brushed motor to the same extent. A brushless motor should lead to a more compact starter.

Cheers

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #46 on: October 18, 2023, 07:20:00 PM »
Thanks for the reply Mike.

I've tried some of the standard brushless motors. There were only two about the right size that were in runners (the I sides go round, not the outside). The problem I found was that for the initial high torque requirement they need to be sensored so they know which way to rotate. I toasted four of them and then gave up.
As you say, I think the Chinese starter ones are a very specific design for high current very short use.

Rob

Online Vixen

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Re: 1/3 Scale Austin Seven
« Reply #47 on: October 18, 2023, 07:40:10 PM »
Hello Rob
Thanks for the reply Mike.
..............................
As you say, I think the Chinese starter ones are a very specific design for high current very short use.

Rob

Sounds like you need to investigate some of the Chinese starters. See if 'EngineDIY' or 'Chuan Qi Precission' will talk to you

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #48 on: October 18, 2023, 10:13:11 PM »
Hi All.

I've added a rough video on YouTube.

<a href="https://www.youtube.com/watch?v=C9RG-cBmTG8" target="_blank">http://www.youtube.com/watch?v=C9RG-cBmTG8</a>

Offline crueby

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Re: 1/3 Scale Austin Seven
« Reply #49 on: October 18, 2023, 11:05:13 PM »
Truly stunning!   :praise2:

Offline Admiral_dk

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Re: 1/3 Scale Austin Seven
« Reply #50 on: October 19, 2023, 07:59:40 AM »
Great sound and a nice + smooth running Engine  :praise2:

Per     :cheers:

Offline Tonyr

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Re: 1/3 Scale Austin Seven
« Reply #51 on: October 19, 2023, 10:23:12 AM »
Looks and sounds great.

Online ddmckee54

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Re: 1/3 Scale Austin Seven
« Reply #52 on: October 19, 2023, 03:51:08 PM »
Rob:

That's a really nice looking dynamo/alternator.  I know it's small, but for a size reference what are the size of the squares in that photo?  You say it's an alternator, where are you putting the electronics to turn it into DC?  I am really going to be impressed if you hid it inside that housing.

Don

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #53 on: October 19, 2023, 05:58:14 PM »
Hi Don,

I've added a picture with a pencil for reference.
I spent a long time experimenting before I came up with this. It's the insides of a brushless out runner dc motor, which is obviously not designed to rotate. That was then added to a shaft and the black cylinder I created a 3 phase bridge rectified (6 diodes). I now had DC so created two slip rings to take the power out. The output then goes through a voltage regulator to hold it at 6.5v. Without the regulator and no load it did spike at over 60v!

Rob

Offline AlexS

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Re: 1/3 Scale Austin Seven
« Reply #54 on: October 19, 2023, 08:13:41 PM »
Very smooth running! well done. And from distance look like 1:1 engine

Offline Chipswitheverything

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Re: 1/3 Scale Austin Seven
« Reply #55 on: October 20, 2023, 08:36:41 AM »
Thanks for posting the video of the engine in action, a wonderful piece of model engineering in performance as well as appearance.  Dave

Offline RReid

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Re: 1/3 Scale Austin Seven
« Reply #56 on: October 23, 2023, 03:27:45 PM »
A most impressive engine! Very well done, Sir! :ThumbsUp: :ThumbsUp:
Regards,
Ron

Online ddmckee54

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Re: 1/3 Scale Austin Seven
« Reply #57 on: October 23, 2023, 10:24:53 PM »
I love the LUCAS stamped into the generator case.  But this actually works, so it must not be a real LUCAS product?

Offline Admiral_dk

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Re: 1/3 Scale Austin Seven
« Reply #58 on: October 23, 2023, 11:26:27 PM »
Lucas - The Prince of Darkness    :o  :Mad:

To be honnest - I haven't tried this with a Lucas System - but others with a Mechanical Relay that is supposed to work as a Voltage Regulator  :hammerbash:

All that was back in my youth .... and I have ABSOLUTELY No wish to replicate the experience again.

Per

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #59 on: October 24, 2023, 09:42:01 AM »
As the saying goes,
Joseph Lucas, prince of darkness.

Offline pgp001

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Re: 1/3 Scale Austin Seven
« Reply #60 on: October 24, 2023, 01:03:37 PM »
Just as an aside, I ran my full size Austin 7 Special on its original 6 Volt dynamo along with the Winter/Summer charge selector switch for over 21 years.
It never gave a moments bother other than having to clean the points in the cutout once every few years.

The lights were always crap, but at least they were consistently crap.

I know a lot of people have converted to 12 Volts, this has the advantage of reducing the current very significantly.

Phil

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #61 on: October 24, 2023, 05:00:51 PM »
That's good to hear. I hope that this dynamo (3 phase alternator) gives similar service.
I have it powering two 6v led torch (flashlight ) bulbs at the moment, which you can see in the video.
I've made a Lucas fuse box and cutout. I wasn't sure which one would have been on a 1933 RP. I went for a CF3 in the end. I'm not using it as I don't want it to get damaged.  I'm using the same voltage regulator, capacitor, fuse etc. in a plastic box.
I'll post some pictures next week.

P.S. If the CF3 is wrong, don't tell me!

Rob

Online ddmckee54

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Re: 1/3 Scale Austin Seven
« Reply #62 on: October 24, 2023, 05:52:36 PM »
I know a lot of people have converted to 12 Volts, this has the advantage of reducing the current very significantly.
That's why automakers went from a 6V system to a 12V system - it cuts the amps in half.  They could use smaller wires in their cars, which meant less of that expensive copper to buy.  A penny saved here and there adds up when you make a LOT of cars.

Offline RReid

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Re: 1/3 Scale Austin Seven
« Reply #63 on: October 24, 2023, 08:44:07 PM »
Years ago, before their values went crazy, my brother had a 356SC Porsche with a 6V system. With the high-ish compression, starting it always sounded painful, as if the battery was almost dead. But it always did start.
Regards,
Ron

Offline Laurentic

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Re: 1/3 Scale Austin Seven
« Reply #64 on: October 25, 2023, 05:26:10 PM »

The lights were always crap, but at least they were consistently crap.


The lights were crap in those days but at the speed cars went then they were probably OK. 

Nowadays, lights are so bright, yes, you can see if they lights are yours, but everyone else is blinded! 

Don't like driving in the dark on busy (meaning most) roads these days!

Chris :old:

PS Absolutely delightful model you have made there - would love to see your build log, along with everyone else!!!

Offline Roger B

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Re: 1/3 Scale Austin Seven
« Reply #65 on: October 28, 2023, 09:03:57 AM »
An excellent runner  :praise2:  :praise2:

Is the SU carb fully functional? How did you calibrate it? I built a quite successful SU type card for my twin.
Best regards

Roger

Offline steamer

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Re: 1/3 Scale Austin Seven
« Reply #66 on: October 28, 2023, 09:15:34 PM »
Sweet!    Nicely done!

Dave
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Damned ijjit!

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #67 on: November 12, 2023, 09:05:28 PM »
Hi.
The SU carb is an exact scale copy of an SU available at the time of this engine. I tried may times to create the origian Zenith and gave up.
They say that as long as the size is about right, then any SU carb will work. What they don't say is how to make it run well. The needle is 0.8mm and tapering down.

I've posted pictures of the Lucas fuse box and cut out (fuse box and voltage regulator).

Rob

Offline Roger B

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Re: 1/3 Scale Austin Seven
« Reply #68 on: November 19, 2023, 07:30:16 AM »
Thank you  :ThumbsUp: I also ended up with a 0.8mm needle. I planned on 0.5mm with a 6mm piston but that was just too small  ::)

Splendid fuse box and cut out  :praise2:
Best regards

Roger

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #69 on: November 20, 2023, 06:03:43 PM »
Hi Roger,

The thing I can't get to work on the SU is the float valve cut off. If you rev the engine, fuel pours out of the top of the float bowl, it has a mechanical fuel pump.

Rob

Offline chris01

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Re: 1/3 Scale Austin Seven
« Reply #70 on: November 20, 2023, 11:17:34 PM »
Is the fuel pressure to large it will make leak . No my triumph tr7 car has same problem on new fuel pump , spring to strong in lift pump. I had to fit pressure regulator to reduce to about 1-2 psi
Chris 

Online ddmckee54

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Re: 1/3 Scale Austin Seven
« Reply #71 on: November 22, 2023, 07:05:59 PM »
As an electrical guy, I absolutely love that regulator/fuse box.  How did you make those covers?  Are they actually stampings like they appear to be?

Don

Offline Austin Seven

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Re: 1/3 Scale Austin Seven
« Reply #72 on: November 22, 2023, 07:29:03 PM »
Hi Chris,
Good point. The fuel pump takes some priming, but once it starts, it's manic!

Hi Don,
I spent a long time machining the covers from solid blocks of brass. I then chemically blackened them.

Rob

 

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