Author Topic: camshafts  (Read 961 times)

Offline shuswapkev

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camshafts
« on: 09.04. 2013 23:19 »

  i need a new cam for my project..

1951 small fin a10... flat top pistons... i have a good 344...but am concerned this will give ride,m mower type power...?????

  i reckon i need a 356...??  but all i can find on ebay are 357,s...  is there much difference??  well...that matters to me??

 this isnt a true resto...  a slow bike gets pretty boring pretty quickly...  in my b33 plunger i swapped out the stock cams for a set of welded up ones..about 1/8 higher and 1/8 wider on top (real technical ..i know) ... but went from a tired old dog...to whoa ho...a bike that would rev right up to scary level...and real good power... of couse.. ..all of a sudden...the plunger suspension ...became a problem...with that  back wheel just bounding around....

looking for advice

Online bsa-bill

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Re: camshafts
« Reply #1 on: 10.04. 2013 10:02 »
Hi shuswapkev

yes big diference, plenty of 356's to be had though, pretty sure someone here will be able to help.

what cam is in there now, I'm not sure you should be looking for a 356 - did that not come later - anyone like to enlighten me/us
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Beezageezauk

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Re: camshafts
« Reply #2 on: 10.04. 2013 10:17 »
I suppose it depends on how you're going to ride the bike.  

The original cams were /are more than adequate for your model but, and this is a big BUT, when BSA started using the 356 and riders were looking for higher constant top speeds and more power, the base flange on the cylinder barrels were prone to cracking and it has been known for the barrels to completely break away from the flanges.  To combat this problem BSA produced the thick flanged barrel in later years.

My thoughts would be....don't even think about a 357 without a thick flange barrel.  Use a 356 with the early barrel if it's only brisker acceleration you want now and again but the 334 will give you a much smoother engine and peace of mind.

Let's face it, the Plunger A10 engines in standard trim produced enough power for the bikes to haul double adult sidecars in their day.

Just my thoughts!!

Beezageezauk.

Online muskrat

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Re: camshafts
« Reply #3 on: 10.04. 2013 11:40 »
 I think she'd take a 356 OK.
 I have a 357 in my 51 A7 with big fin head & barrels (thin flange) but A7's rev harder than A10's.
Cheers
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Online KiwiGF

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Re: camshafts
« Reply #4 on: 10.04. 2013 12:31 »
I boughtva 356 cam from srm whereas my 56 a10 as std has a 334, its not much different in terms of lift etc from the 334 from memory maybe 015" more lift, the 357 however has a significant amount of extra lift over the 334 ...my 2 cents worth is get a 356 and not get a 357 unless you are a speed freak like musky  *smile*
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Offline shabashow

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Re: camshafts
« Reply #5 on: 01.05. 2013 13:00 »
I put in a 356 in my '52 gold flash when I built her 5 years ago, mainly because it was the only camshaft I could find at the time. Haven't noticed any problems, and I appear to have plenty of power, and the engine runs smooth.

Online Topdad

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Re: camshafts
« Reply #6 on: 01.05. 2013 13:12 »
My first A10 was pretty much as beezageezauk described , double adult sidecar on a 53 plunger a10, I was 16 so at first even that was fast enough but come a month or so big chair off flat board fitted and she became " sporty" I can confirm that even standard you could bounce the valves through the gears, poor thing was hammered unmercilessly but always pulled like a train. , hope you find the one you want ,regards BobH.
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Online Rocket Racer

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Re: camshafts
« Reply #7 on: 04.05. 2013 06:18 »
small journal crank, thin flange barrels...use the extra punch from a hot cam and watch it go bang  *sad2*, or run it with a 334 where it should remain fairly bullet proof if properly maintained and still be good for the ton.
The early super flashes were known for having way too much power for the plunger frame, so personally I'd be sticking to the stock 334 if I were you.
However my B33 still runs a stock cam and carb, but although no record breaker, goes everywhere full tit and has been commented on as "must be hotted up" because some fellow BSAOC members have been left for dead on their lightnings trying to keep up. I just like to ride hard, don't need a fast bike, just keep the throttle open.
A 334 will be better on hills and under 5000rpm -enjoy it for what it is.
I'd love to see what happens if you take a stock early motor to 7200 like I do my race A10. Will go really well for a short time  ;)
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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