Author Topic: Easy way to identify B25 camshaft  (Read 158 times)

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Trebor

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Easy way to identify B25 camshaft
« on: 16 May, 2022, 19:52:32 »
Hi all

Is there a quick way to identify the correct camshaft for a 69 B25. The cam I have has no markings on it (other than a single line timing mark), the exhaust lobe appears to be wider than the inlet lobe (opening the exhaust valve for longer than the inlet???), is this standard??

Also, in a number of adverts they state that the same camshaft can fit B25, B44 and standard B50 (not MX). Does this mean its the pinion wheel that is model specific and not the cam.??

I note there is a new cam for sale on ebay at the moment and it is stamped with what appears to be a "O".??

Advice would be appreciated.

Rob

Spaceman

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Re: Easy way to identify B25 camshaft
« Reply #1 on: 16 May, 2022, 20:59:57 »
Rupert Ratio indicates the B25/B44 and B50 had the same camshaft lobe designs. Although the B25 and B44 shared the same camshaft, the B50 has a different part number and underwent some other design changes according to RR.

Spaceman

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Re: Easy way to identify B25 camshaft
« Reply #2 on: 17 May, 2022, 06:58:26 »
Just to elaborate, apart from the B50MX and B44GP, the B25, B44 and B50 engines all had the same valve timing and therefore all have identical inlet and exhaust cam lobes. However, as far as I can see the inlet cam lobes provide a slightly longer dwell than the outlet cams but they are very close in shape.

I think the problem you have for the B25 is that a number of changes were made to the camshaft and it's pinion and there are therefore a total of 4 x part numbers. Some of these may only have affected how the pinion fitted on to the cam shaft (change in Woodruff key size?) but I think the 1971 cam shaft may have had a thinner pinion wheel.

It's therefore possible that a 1970 camshaft would be ok for a 1969 B25 but a 1971 camshaft may not. It might be worth asking the eBay seller if he knows which year the camshaft he is advertising came off. I would have to try and check but the elaborate timing marks on this cam pinion might suggest its from a 1971 B25??

Obviously, if you still have the original camshaft, it would be possible to compare the two especially in terms of if they display the same timing marks.

Trebor

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Re: Easy way to identify B25 camshaft
« Reply #3 on: 17 May, 2022, 08:33:21 »
Hi

Thanks for the responses, it would seem to me that its the pinion wheel that is model specific and goes some way to explain why you can have up to three timing marks on a cam wheel. You can understand the logic from a financial point of view if you are making pinion wheels where the only difference is a stamped mark, why not use one pinion with a different stamped make for each model???

Thanks

Rob