worthidlj
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| posted on 27/1/12 at 09:58 PM |
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Minor muse and thought update.
Good thing is the ZXR400 rotates in the same direction as the Austin 7 motor and pistons and crank are the same layout.
Firing order is different though (A7: 1-3-4-2 plays ZXR: 1-2-4-3) but as I would be using the fueling and ignition from the ZXR it shouldn't
casuse any issues.
The issue now would be driving the cams...main issue being that the A7 is gear driven and ZXR is chain driven, also with the design of the A7 engine
the cam gears on the ZXR head would sit behind the gear on the crankshaft.
Sooooooo, how to overcome this conumdrum (especially theoretically as I actually don't physically have any of the parts  ); one thought I had
was to in keep with the original design and build a gear-drive mechanism, either using extra A7 crank and cam gears or custom ones with a fabricated
mount from A7 cam gear to ZXR cam gears.
I'm trying to get hold of dimensions for a mock-up to see how it could be done.
Bit of a waffle but kind of where I'm up to at the mo... if it seems feasable enough and may even try to do it for my note Open Uni module!!
Any advice/opinions always welcome.
Cheers,
David
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matt_gsxr
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| posted on 27/1/12 at 10:41 PM |
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whole zxr400 engine on that auction site presently at £102.
Sounds like you have done enough theory to have a punt.
Your plan-B could be to put the whole engine in!
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worthidlj
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| posted on 28/1/12 at 04:17 PM |
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quote:
Originally posted by matt_gsxr
whole zxr400 engine on that auction site presently at £102.
Sounds like you have done enough theory to have a punt.
Your plan-B could be to put the whole engine in!
Possibly enough theory but time, space and money are out of the question at the moment; uni work, full time job(low paid ), scouts, swim coaching and
still living at home with the parents mean this is just theory at the moment and are just plans for a couple of years time at the moment.
Plus getting hold of as much info as I can now means I don't have to waste time asking companies can I measure certain components...people on
the austinsevenfriends website have been very helpful giving me the information I request.
I think the only distances I need now is the distance between the two centres of the camshafts of the ZXR400 cylinder head, how far they are from the
centre of the cylinder bore of the ZXR400 engine, and finally, how high the centre of the camshafts are from the bottom face of the cylinder head.
If anyone can provide theses dimensions I would really appreciate it.
Cheers,
David
[Edited on 28/1/12 by worthidlj]
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worthidlj
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| posted on 2/10/12 at 05:58 PM |
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More fuel for the fire!!
Thread bump again!!
Uni work has restricted any reasonable research, but searching on ebay has found a supplier (cradleykawasaki - no affiliation!) who was kind enough to
give me a couple of dimensions.
Turns out the bore spacing is approx 67.5mm; now the bore spacing for an Austin Seven engine is 2.625inch, converting this to mm means there's a
difference is approx 0.83mm.
Does this seem too much of a difference or do you reckon I could get away with a bit of machining to allow the valves to movw without hitting the
bores?
Further inspiration comes from a PPC article where somone fitted a zetec head onto an MGB B-Series block, even though the cylindes are siamesed, so
maybe some hope!! :-)
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steve m
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| posted on 2/10/12 at 06:49 PM |
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If i am reading this right, you want a lot more power out of an austin 7 engine?
If i am reading it all correct, !!
have you ever driven an Austin 7 on the road ? as i have, and more power out of the engine is not required,
brakes that work is a MUST first
The old Austin 7, and the like were never designed for the modern world, and the brakes were never designed to actually work
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worthidlj
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| posted on 2/10/12 at 11:10 PM |
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quote:
Originally posted by steve m
If i am reading this right, you want a lot more power out of an austin 7 engine?
If i am reading it all correct, !!
have you ever driven an Austin 7 on the road ? as i have, and more power out of the engine is not required,
brakes that work is a MUST first
The old Austin 7, and the like were never designed for the modern world, and the brakes were never designed to actually work
It's not that I would want A LOT more power (though I believ some road/racers push 40-50hp N/A).
I haven't deiven an Austin 7 but would like to. The engine is not just what I would do, I would look
at doing brakes and suspension before doing this kind of the thing to an engine; remember I don't
actually own any of the parts yet (lack of money/space/ability/etc). This is more just initial musings
to see if the theory is 'relatively' sound. Plus I would like to make a body like some of the old 'Specials'
Essentially it boils down to is why not? plus could be fun to actually do as well
Cheers,
David
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Dingz
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| posted on 21/10/12 at 03:52 PM |
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[img]
 
Description
[/img]
If this works here is a poor picture of a twincam supercharged Austin 7 engine just as a thought.
 
Austin 1
Interesting thread this, many years ago I half built an A7 special and got it to a running stage, see above, this was when I discovered that firstly
the clutch is a switch just in or out. Fortunately the engine didn’t seem to have any power or torque band it just ran at different speeds so the car
would just jump forwards. The brakes were hopeless even when only fitted with a bit of wood and aluminium as a body so anyone driving one on the road
with standard brakes must be very brave. The design of the front braking is not good, the cables pull the brakes on, as the brakes start to work the
reaction from the hub twists the axle rearwards, releasing the force applied by the cable, so it is a sort of self regulating system, ensuring the
brakes can’t work very well.
Regarding the crank failures, the engines were bolted down to the A frame chassis by 4 bolts through lugs on the engine a sort of extended sump
flange, when the chassis twisted it twisted the block which helped the crank to snap, Colin Chapman discovered with his racers that if you only used 2
bolts crank life expectancy was much improved.
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
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worthidlj
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| posted on 9/5/14 at 12:58 PM |
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update/ query
ok not written in a while but enjoying reading other peoples projects.
I've potentially located a cylinder head and keeping an eye on a block too.
Though bore centres are very similar I am slightly concerned of valves hitting the bores.
Would it be possible to grind small recesses into the tops of the bores to allow the standard
valves to be used, and if so what tools would you recommend to do this kind of work?
Cheers,
David
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owelly
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| posted on 9/5/14 at 02:00 PM |
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Yes you can 'pocket' the edges of the bores but you'd be chipping into the area where you don't want to! You'll end up
creating hot-spots and encroaching on the fire ring. You would be better using smaller headed valves, with undersized seats, lifting the seat faces up
into the head and using dome-topped pistons or (my preferred method!) machining a new head from billet alloy!
http://www.ppcmag.co.uk
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worthidlj
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| posted on 9/5/14 at 03:14 PM |
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Thanks for the reply, I'm hoping I wouldn't have to but would just like to try and cover any eventualities.
If I did have to pocket the bores what tools would you recommend for a DIY-er?
Cheers,
David
P.S. Owelly, I enjoy reading your exploits in the PPC mag
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sebastiaan
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| posted on 9/5/14 at 03:15 PM |
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This:
quote:
Originally posted by worthidlj
Firing order is different though (A7: 1-3-4-2 plays ZXR: 1-2-4-3)
Is a deal-breaker. Or at the least will require different cams for the head. 1342 and 1234 would be interchangable using the same crank, but 1342 and
1243 won't be. Think about it ;-)
Full point for the idea though, and getting custom cams made up should be possible, though expensive.
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worthidlj
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| posted on 9/5/14 at 03:31 PM |
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quote:
Originally posted by sebastiaan
This:
quote:
Originally posted by worthidlj
Firing order is different though (A7: 1-3-4-2 plays ZXR: 1-2-4-3)
Is a deal-breaker. Or at the least will require different cams for the head. 1342 and 1234 would be interchangable using the same crank, but 1342 and
1243 won't be. Think about it ;-)
Full point for the idea though, and getting custom cams made up should be possible, though expensive.
Thanks for the input Sebastiaan.
Yeah that's a bit of an oversight on my part, my concern had been having a similar crank set up (i.e. looking at the profile of both cranks is
"up-down-down-up) as I thought that if these were similar then I could just use the firing order of the ZXR head, or am I thinking wrong.
As you say I will probably have to look at custom cams but it's a project so all part of the fun!
Cheers,
David
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SteveWalker
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| posted on 9/5/14 at 03:42 PM |
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1-3-4-2 and 1-2-4-3 are surely interchangeable? 1 and 4 are up together and 2 and 3 are up together. Reversing the firing order within either or both
pairs would be okay, you just can't change between pairs.
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redturner
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| posted on 9/5/14 at 07:03 PM |
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This will maybe help with your research. Check out the Turner twin cam head designed by Jack turner. He designed this for his 500cc racing engine but
it was fitted to an A series engine for development. The 500 engine complete with the twin cam head can be seen in the Coventry Motor Museum. Might
give you a few ideas.
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