Author Topic: B40 valve guide question  (Read 52 times)

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chaz

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B40 valve guide question
« on: 12 October, 2019, 18:34:21 »
have decided to replace the guides on the boys B40 its a 1965 big head inlet valve.
Ruperts book is at the unit, Im looking at ordering parts at home.
the inlet valve for 41-0024 has a related items option of 41-0632 phos bronze guide.
going by the parts page.
has two 1965 options
41-0021 phos bronze
41-0027 cast iron

1961-64 has two cast iron fitted
1965 has one of each fitted

should there be one of each or a pair of phos bronze ( my personal choice)

JulianS

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Re: B40 valve guide question
« Reply #1 on: 12 October, 2019, 19:02:25 »
Dont know about the material but the inlet and exhaust guides were not identical. The later exhaust guide, well the BSA made ones, had a counterbore to prevent the valve sticking due to carbon build up on the stem.

See service sheet below.

chaz

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Re: B40 valve guide question
« Reply #2 on: 12 October, 2019, 19:49:41 »
thanks Julian
more confusion then.

41-0017 is cast iron
41-0021 is bronze but out of stock
both parts come under B40 but is there any mention anywhere on the B40 page of 41-0632 which is in stock and in Bronze.
I was thinking iron due to the exhaust temperature but why Drags have decided to include bronze as a not on the valve picture?

edit
on searching this is normally for a B44 or B25 inlet valve Alpha G510PB , phos bronze used for their non stick abilities an improvement to cast iron so why not just one option nowadays?
without your sheet there is no mention of which goes where, so thanks

edit 2
even ebay does not have 41-0021 but does have 41-0632, confusingly  both the -0017 and -0632 are available in pairs!!
« Last Edit: 12 October, 2019, 19:55:09 by chaz »

JulianS

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Re: B40 valve guide question
« Reply #3 on: 12 October, 2019, 20:34:16 »
41 632 =B44 inlet guide.

41 633 =B44 exhaust guide.

The WD B40 spares list gives inlet guide 41 17 cast iron and exhaust 41 21 also cast iron.