worthidlj
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| posted on 20/1/12 at 05:27 PM |
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Alternative Heads!?
Evening all,
I've enjoyed reading about others experiences and projects and would like to delve into the think tank.
I'm having some musings at the moment and was wondering if anyone had an idea of any 4-pots that have a cylinder centre spacing of 66.67mm or
2.625" (likely to be a 500-750cc bike engine?!). Specific I know but I have a reason.
Thanks in advance.
Cheers,
David
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James
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| posted on 20/1/12 at 06:01 PM |
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Probably worth saying what block you would like to fit it to. Not wanting to denegrate the knowledge of my fellow LB members but I can see people are
more likely to remember having randomly read on some forum that head X fits block Y than they are to remember that head X has a certain centre
spacing! 
Or maybe I'm wrong, some people on here are pretty encyclopaedic!
Just trying to ensure you get what you want!
James
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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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pewe
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| posted on 20/1/12 at 06:26 PM |
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IIRC someone fitted a BMW K75 bike cylinder head (Brick) to a BMC A series (old school Mini) engine if that helps as a starting point?
Cheers, Pewe10 
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scootz
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| posted on 20/1/12 at 06:45 PM |
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BMW K1200 head is another popular choice!
Linky
It's Evolution Baby!
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worthidlj
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| posted on 20/1/12 at 07:31 PM |
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Thanks
Thanks for the reply folks;
I have read a bit on the mww/a-series conversions, unfortunately the bore spacing is too big!! 
As I said these are just musings at the moment... the idea would be to build an Austin Seven Special
and try and convert it to a twin-cam head. OHV conversions were available waay back in the day
so i reckon an dohc can be done; for no other reason other than it doesn't appear to have been done
before.
I have been able to find bore spacing (i.e. centre of one cylinder bore to the middle of the next one.),
as mentioned in initial post, of 66/67mm personal research hasn't revealed anything but I was hoping
someone on hear may have a beeter knowledge and would be willing to share.
Please remember that this is just ideas floating in my head (not much for it to bump into either ) and
it'd be a good few years before I had time, space and money to start it.
Skill...I'll probably never have but I think this would be a great project to learn with!!
Thanks again for your time.
Cheers,
David
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Neville Jones
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| posted on 20/1/12 at 07:36 PM |
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An old three bearing crank with a 16v head on top would not be very good friends.
Cheers,
Nev.
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worthidlj
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| posted on 20/1/12 at 07:51 PM |
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quote:
Originally posted by Neville Jones
An old three bearing crank with a 16v head on top would not be very good friends.
Cheers,
Nev.
Very true, I just wanted to see if it was theoretically possible as I think it would
be an interesting little engineering project.
Cheers,
David
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Cornishman
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| posted on 20/1/12 at 08:22 PM |
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Dont use a 3 bearing engine Austin Seven engine, they were only produced for a short time and are well known for centtre bearing problems. Some of
the 50's special racers got it to work but most stuck to the 2 bearing.
The better engine to use is the 2 bearing engine, despite the fact that the crank "whips"
A company called Pheonix crankshafts have now produced thousands of 2 bearing cranks for Austin Seven engines
that have practically solved the traditional handicap of cranks breaking at the rear journal. You can also go to pressure feed instead of spit and
hope lubrication.
To allow for the whip it is customary to machine 20 thou off the pistons of 2 and 3 to stop them touching the side
valve head at high revs, so not sure how your OHV conversion is going to cope with this as your valves will be facing the pistons not sitting next to
them?
The works racing versions had special blocks cast that had more holding down studs on the base and
also many more studs holding the heads on.
And I presume that you are aware that Austin produced a twin cam racer thereselves pre war?
Good luck , sounds interesting and if you are serious go look at the austinsevenfriends forum and ask questions.
Steve
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MikeRJ
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| posted on 20/1/12 at 08:41 PM |
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quote:
Originally posted by Neville Jones
An old three bearing crank with a 16v head on top would not be very good friends.
Cheers,
Nev.
And yet it's been very successfully done many times. The A series might be an old engine but it's a very strong one, and it's quite
possible to build a bottom end that will take 8000RPM or more. Even the owners manual for the Metro Turbo stated it was permissible to take the
engine to 7000RPM on acceleration (i..e not holding in there).
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worthidlj
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| posted on 20/1/12 at 10:48 PM |
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quote:
Originally posted by Cornishman
Dont use a 3 bearing engine Austin Seven engine, they were only produced for a short time and are well known for centtre bearing problems. Some of
the 50's special racers got it to work but most stuck to the 2 bearing.
The better engine to use is the 2 bearing engine, despite the fact that the crank "whips"
A company called Pheonix crankshafts have now produced thousands of 2 bearing cranks for Austin Seven engines
that have practically solved the traditional handicap of cranks breaking at the rear journal. You can also go to pressure feed instead of spit and
hope lubrication.
To allow for the whip it is customary to machine 20 thou off the pistons of 2 and 3 to stop them touching the side
valve head at high revs, so not sure how your OHV conversion is going to cope with this as your valves will be facing the pistons not sitting next to
them?
The works racing versions had special blocks cast that had more holding down studs on the base and
also many more studs holding the heads on.
And I presume that you are aware that Austin produced a twin cam racer thereselves pre war?
Good luck , sounds interesting and if you are serious go look at the austinsevenfriends forum and ask questions.
Steve
Hi Steve,
Below is a link to a patented OHV conversion, I have also been on the austinsevenfriends forums often reading up on things and posting a couple of
queries too. One reason I posted this in here is if I tried posting there I may get lynched!!
[HTML]http://bruce-white.austinharris.co.uk/Overhead_Valve_Conversion.htm[HTML]
I have heard of the phoenix cranks, the 'whiplash effect' and the 2/3 bearing conumdrum and the forum is a great source of info. I have
heard of the Austin Twin Cam, but I understand it had a completly redesigned engine, nothing like a standard sports versions. Thanks for your
input.
Cheers,
David
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MikeRJ
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| posted on 20/1/12 at 11:07 PM |
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quote:
Originally posted by worthidlj
Hi Steve,
Below is a link to a patented OHV conversion, I have also been on the austinsevenfriends forums often reading up on things and posting a couple of
queries too. One reason I posted this in here is if I tried posting there I may get lynched!!
[HTML]http://bruce-white.austinharris.co.uk/Overhead_Valve_Conversion.htm[HTML]
Thanks for posting that, very interesting. I suspect getting enough valve lift for the valves opposite the pushrods might be a problem!
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PSpirine
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| posted on 20/1/12 at 11:47 PM |
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Interesting reading!
By some unknown coincidence I was looking at some car parts on ebay just now and this appeared as one of the listings advertised on the bottom:
Austin 7 Seven Phoenix crankshaft | eBay
Not sure if it's relevant, but seems a lot for a Austni 7 crank!
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James
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| posted on 21/1/12 at 02:04 AM |
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Why only upgrade half the engine? Do the job properly and make your life easy by changing the whole thing! 
Cheers,
James
------------------------------------------------------------------------------------------------------------
"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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worthidlj
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| posted on 21/1/12 at 09:44 AM |
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quote:
Originally posted by James
Why only upgrade half the engine? Do the job properly and make your life easy by changing the whole thing!
Cheers,
James
Because I think it would make an interesting project; plus the chassis, drivetrain and brakes (even modified) can't handle a huge large
increase. I just think it would be an ingenious way of tuning it whilst still retaining some form of originality.
Cheers,
David
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Cornishman
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| posted on 21/1/12 at 01:14 PM |
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I think we are talking about the pre war Austin Seven engine not the later A series!
The pheonix crank in 1"5/16" non pressure feed is about £750 new plus the same for their rods.
The pressure fed versions and the larger 1"1/2" sizes are priced differently.
You would be suprised about the friends forum, yes they have some rivet counters on there but
there are also some very skilled engineeers on there who are interested in modifications.
I think Pigsty racing are getting 50 plus BHP out of their 750cc sidevalves, which in a special weighing
about 250-300Kg is enough to have fun given the limitations of cable brakes!!!
Before building up this hillclimb Locost I was seriously looking at building another Austin Seven special
as a smaller scale copy of the Locost design and using a Reliant OHV engine that I just happen to have here.
I'd be very interested in your progress if you make any
Steve
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PSpirine
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| posted on 21/1/12 at 01:29 PM |
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We all love a good engineering project - as you say, it's as much about the journey as the destination.
We're not building kit cars cause it makes sense, we do it cause we enjoy it!
Whatever you decide to do, definitely start a build thread on here - I'll be following with interest.
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worthidlj
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| posted on 21/1/12 at 04:55 PM |
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Thanks for the comments guys,
I know there are likely to be those who would appose this on ASF (Austin Seven Friends) and who would support it but I jusy feel that this forum would
give me a bit more insight on bike heads and dimensions, especially those with BEC's.
I've heard about the Reliant OHV being used in Seven Specials but can't find much on the net of people who have done it.
I wouldn't hold your breath though as it would be a few years before I get close to een thinking about starting it. Work and Open University see
to that.
If/when I do start I'll be sure to keep posted.
Cheers,
David
[Edited on 21/1/12 by worthidlj]
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MikeRJ
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| posted on 21/1/12 at 09:24 PM |
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quote:
Originally posted by James
Why only upgrade half the engine? Do the job properly and make your life easy by changing the whole thing!
Cheers,
James
Because changing the engine block and gearbox requires chopping up the subframe, and then opens the door for SVA/IVA issues. You also have the hassle
of getting custom drive shafts made, special gear linkage etc.
There are hundreds of 16v conversions on A series blocks that work perfectly well.
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worthidlj
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| posted on 24/1/12 at 12:34 PM |
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research udate
Good afternoon guys,
After a few days searching I have found a few bike 4-bangers with areasonable bore size; either original size or ones that can be used in a bored out
block:
- Kawasaki ZXR400 - 57mm bore.
- Kawasaki GPZ550 - 58mm bore.
- Yamaha FZR400 - 56mm bore
- Yamaha XJ550 - 57mm bore.
Unfortunately I cannot find any info online aboutthe bore spacing for these bikes so was wondering if anyone on here knew or know someone that did?
Thanksin advance.
Cheers,
David
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pewe
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| posted on 24/1/12 at 12:50 PM |
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There's an engineering company in Fleet called Roe Engineering who specialise in engine overhauls.
He's pretty knowledgeable about a huge range of engines so might be able to offer advice.
HTH.
Cheers, Pewe10
[Edited on 24/1/12 by pewe]
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matt_gsxr
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| posted on 24/1/12 at 01:25 PM |
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If you google for head gaskets of these then you should be able to get some approximate dimensions.
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worthidlj
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| posted on 25/1/12 at 12:57 PM |
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Minor update...
Finding parts lists with exploded diagramsof these bikes show that cylinder head design of thee mean that cylinders 2 and 3 are too far spaced apart
so the only option left is the Kawasaki ZXR400.
Internet trawlinghas returned no results with regards to it'sbore spacing.
The best I have been able to do is get a picture of a head gasket; blow it up to A4 measure the bore size and wall thickness of the picture (52 and
9mm respectively) and knowing the actual bore size (57mm) I have calculated actual wall thickness being 9.8653846153mm, therefore giving a calculated
bore spacing of 66.8653846153mm.
Now scaling of the photo and printer are likely to have skewed the measurements but with the Austin engine having a bore spacing of 2.625" aka
66.675mm gives mehope that with a bit of recessing around the top of the bores gives the faint whiff of hope!!
The challenge now would be to get a block and gasket together (unless someone could confirm the ZXR400's bore spacing - I've sent a few
emails and awaiting replies) and see how everything lines up!!
One last thing though: do both engines turn the same way? If not I would have to look into getting custom cams made to allow the cams to work in the
new layout which also has the advantage of being a crossflow design keeping the exhaust on the normal side making fabrication easire to deal with!!
Thanks for the interest.
Cheers,
David
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nick205
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| posted on 25/1/12 at 02:02 PM |
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My old boss is an Austin nut and runs a Speedy (Austin 7 based factory special) which he's rebuilt a number of times. The Achilles heal of the
whole car seems to be the engine. Bearing in mind he has to keep everything original down to the felt oil seals to preserve the originality and value
of a fairly rare car. He's had various engines built and rebuilt right up to a newly cast block and billet crank (all made to OE spec) and
they're just not reliable.
Obviously you're machine wouldn't be standard with a 16v head which makes me think it would be much more effective to select a suitable
complete engine and fit that - it would have to be something small though - Coventry Climax or maybe a sub 1,000cc bike motor...?
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worthidlj
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| posted on 25/1/12 at 02:43 PM |
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quote:
Originally posted by nick205
My old boss is an Austin nut and runs a Speedy (Austin 7 based factory special) which he's rebuilt a number of times. The Achilles heal of the
whole car seems to be the engine. Bearing in mind he has to keep everything original down to the felt oil seals to preserve the originality and value
of a fairly rare car. He's had various engines built and rebuilt right up to a newly cast block and billet crank (all made to OE spec) and
they're just not reliable.
Obviously you're machine wouldn't be standard with a 16v head which makes me think it would be much more effective to select a suitable
complete engine and fit that - it would have to be something small though - Coventry Climax or maybe a sub 1,000cc bike motor...?
The engine swap had crossed my mind but I just want to do this for myself;with it being based on using a Special so originality/rarity is less of an
issue. Plus keeping core components standard, or modified versions of standard parts, it would allow me to circumvent the IVA test and make it easier
to return to original specs.
Remember this is all a pipe dream at the moment and am just checking feasability for a, hopefully, few years time.
Cheers,
David
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nick205
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| posted on 25/1/12 at 10:38 PM |
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quote:
Originally posted by worthidlj
quote:
Originally posted by nick205
My old boss is an Austin nut and runs a Speedy (Austin 7 based factory special) which he's rebuilt a number of times. The Achilles heal of the
whole car seems to be the engine. Bearing in mind he has to keep everything original down to the felt oil seals to preserve the originality and value
of a fairly rare car. He's had various engines built and rebuilt right up to a newly cast block and billet crank (all made to OE spec) and
they're just not reliable.
Obviously you're machine wouldn't be standard with a 16v head which makes me think it would be much more effective to select a suitable
complete engine and fit that - it would have to be something small though - Coventry Climax or maybe a sub 1,000cc bike motor...?
The engine swap had crossed my mind but I just want to do this for myself;with it being based on using a Special so originality/rarity is less of an
issue. Plus keeping core components standard, or modified versions of standard parts, it would allow me to circumvent the IVA test and make it easier
to return to original specs.
Remember this is all a pipe dream at the moment and am just checking feasability for a, hopefully, few years time.
Cheers,
David
Totally understand (and support) the because I want to approach the challenge is there to be done
Keep us posted on your musings and research - as you've seen there's a huge amount of resource available on the site.
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