Its of topic, bud can someone tell me if I can
Put goldstar cams and piston in a B33 engine?
Ore are the cams and pistonfrom a B33 the same
As from the Goldstar ?
Regards
Bram
email (option): bram@ockhuizen.com
The Gold Star had a range of different cams through the years for different applications and for 350 and 500 engines...
They can be fitted to B33 engines with varying degrees of modification to the engine
The best cam for road use in my opinion is the Gold Star scrambles cam 65-2446...This can be used with the original B33 valve springs but you must check that the top valve spring collar doesn't touch the shoulder of the valve guide at maximum lift...If it does, or if it's very close the tops of the guides should be shortened...Fit the same cam to the inlet and the exhaust..
Open the inlet port to 30mm or 32mm and fit a matching carb..
The Gold Star 500 piston can be fitted but only if you have a 'long rod' B33 engine...Also, check compression ratio and valve to piston clearance...
'Long rod' conrods are 7 3/8" between centres...'Short Rod' conrods are 6 7/8" between centres...
Personally I would aim for an 8.5-1 compression ratio which will probably mean you have to fit a decompression plate under the barrel...Doing that will solve any potential valve clearance problems as a bonus...
That will give you a reasonable boost in power....If you really want it to go, lighten the crankshaft as well...Ian
email (option): ian@wright52.plus.com
Thanks Ian and Ian,
I have a B33 from1957 do you know if that is the long
or short stroke ?
And have someonethe 65-2446 cams for sale?
Ore a adres to buy.
Regards
Bram
email (option): bram@ockhuizen.com
['The rough calculation is; if you want to double your speed you need to over come four times the wind resistance and need eight times the power.']
True, but not very relevant when applied to what most people are doing..
Most aren't trying to double the speed..In fact with a British bike they are probably looking at a 10-20% increase after tuning...
However, in most cases an increase in low and mid range power is more what they are after to make the bike more useable/exciting under normal road riding conditions...
This alters the equation somewhat as wind resistance isn't even a factor up to about 60-65mph...Power to weight ratio is the important thing up to those speeds...
I agree entirely with your comments on compression ratios...High compression ratios don't do British engines any favours with loadings and combustion problems..and aren't even necessary to get a good power increase.
I got over 40bhp at the engine, measured on a dyno, from a B33 engine running an 8.75-1 compression ratio...
Bram, You can buy new Goldie cams from David Newman Camshafts or Autocycle Engineering.....(David Newman manufacture for both companies)...
I have used these cams many times...
I think your B33 will be a short rod motor but you can never be sure as things get changed over time...
If you measure the distance from the centre of the gudgeon pin to the top of the piston I can confirm which one you have....Ian
email (option): ian@wright52.plus.com
Thanks Ian,
Will leth you know when dismantled the engine.
Is there a proper way to calculate the compression ratio??
For the cams that may also be good used cams.
regards,
Bram
email (option): bram@ockhuizen.com
If you have a flat piston fitted the calculation is easy..
Cylinder volume + cylinder head volume divided by cylinder head volume...
So for a standard long rod B33 which has a flat piston and a 90cc head volume...
499 + 90 = 589..divided by 90 = 6.5-1....
To calculate the cylinder volume use 3.142 x R x R x L where R is the bore radius and L is the stroke..So for a B33 as described above which has an 85mm bore and 88mm stroke...
3.142 x 42.5 x42.5 x 88 = 499cc..
If you have a domed piston things get more difficult as the standard head volume changes and you have to determine the new volume before making the calculation...
The only way to do this is to physically measure the head volume...
After fitting the new (high compression) piston turn the crank to the TDC position...Now smear some thick grease around the edge of the piston to seal the gap between the piston and bore. Carefully wipe away any excess grease...
Next refit the cylinder head....smear some grease on the head joint as well when you refit the head to ensure a good seal here...
Take care not to move the crank at all during this process!!
Now tilt the engine until the spark plug hole is at the highest point...
Fill a flask graduated in cc with a carefully measured amount of thin oil..say 250cc...
Using a suitable funnel carefully fill the cylinder until the oil is just visible at the bottom of the plug hole...
Now leave the flask to stand so that the oil 'settles' again and read off the amount you have left...With this figure and the figure you started with (250cc in this case) you can now calculate how much oil is in the cylinder...
This will be less than the standard 90cc volume, so for sake of example we will say 60cc...
Using the formula above... 499 + 60 divided by 60 = 9.3 (9.3-1)..Ian
email (option): ian@wright52.plus.com