Author Topic: Can an A10 top end go on an A7 bottom end?  (Read 2100 times)

Offline 900triple

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Can an A10 top end go on an A7 bottom end?
« on: 14.10. 2008 22:08 »
Hi,

New to this site (excellent first impressions BTW).

I am putting together a non standard 1953 ish plunger A7 and am trying to find out if its possible to put an A10 top end on the engine...and if so whats involved.
This has probably been covered many times but any advice would be welcome.
Cheers
Alan

Offline trevinoz

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Re: Can an A10 top end go on an A7 bottom end?
« Reply #1 on: 14.10. 2008 22:37 »
Only if you strip down and replace the crank and rods, so I guess the answer is no.
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Offline a10gf

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Re: Can an A10 top end go on an A7 bottom end?
« Reply #2 on: 15.10. 2008 21:11 »
Welcome onboard Alan, I hope you will find all the help you may need. Post any stories and pictures about your ongoing restoration.

e

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"Success only gets you a ticket to a much more difficult task"

Offline fido

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Re: Can an A10 top end go on an A7 bottom end?
« Reply #3 on: 16.10. 2008 09:06 »
If you want a bit more power I suggest you build the engine to A7SS spec. with higher comp. pistons etc.

Offline 900triple

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Re: Can an A10 top end go on an A7 bottom end?
« Reply #4 on: 16.10. 2008 10:32 »
If you want a bit more power I suggest you build the engine to A7SS spec. with higher comp. pistons etc.

Thanks for all of the posts - I am after more grunt rather than power and revs plus the engineering challenge (however slight) of a conversion....

So far it sounds as if a crank/rod plus top end change may suffice?

Offline trevinoz

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Re: Can an A10 top end go on an A7 bottom end?
« Reply #5 on: 16.10. 2008 21:44 »
Alan, what you are intending is building an A10 engine in A7 crankcases which is no trouble as the cases are the same. Use a 356 or 357 camshaft, you may have to ease the cam tunnel to fit.
I would go for the 356 cam which is what the Super Flash used and would develop as much power as a plunger frame can handle, unless you are a thrill seeker.
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Online Brian

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Re: Can an A10 top end go on an A7 bottom end?
« Reply #6 on: 16.10. 2008 22:26 »
I would totally agree with Trevinoz. Use the 356 cam and go for around 7.5-1 compression and you will have a very nice motor to suit the plunger frame.

I have this setup in my plunger A10. I run standard gearing and the bike will cruise all day at 60-65mph.

Online olev

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Re: Can an A10 top end go on an A7 bottom end?
« Reply #7 on: 17.10. 2008 11:21 »
Gday Alan,
recently read (on the internet) about an early american racer who stuck an a10 top end on an a7 by machining the top fin off a set of a10 barrels to match the shorter conrods. He was apparently quite successful in the 500cc division for a while. I looked again but can't find the site. lets face it, you can't beat cubes.
good luck, tom

Offline beezalex

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Re: Can an A10 top end go on an A7 bottom end?
« Reply #8 on: 24.10. 2008 21:15 »
I would go for the 356 cam which is what the Super Flash used and would develop as much power as a plunger frame can handle,

Is there a power limit to the plunger frames?  Do they have a particular weakness?  I'm planning on racing one so some info or experience would be appreciated here.
Alex

Too many BSA's


Offline jfligg

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Re: Can an A10 top end go on an A7 bottom end?
« Reply #9 on: 26.10. 2008 14:21 »
Hi Alex  Can you tell us more aout your plunger race bike?  Got any pictures.  Jeff