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Kerry W
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B40M Roughrider Engine Compatibility
#785294 09/24/19 6:21 am
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I am now getting round to doing something with My Roughrider. I only have a NOS set of 68 dated cases, barrel piston and head at present. I should shortly have access to a large stash of used mainly B44 late 60s parts so hopefully someone can confirm what I can use. I believe I can use the gearbox and primary complete, as well as the oil pump, cam & tappets. What I'm unsure about is the crankshaft, the timing and oil pump drive gears, the conrod (big end/ length?) and pushrods (length?). Some useful info was put on my other B40GA thread, but I would be grateful for any confirmation of the above info.


1966 Triumph Thunderville
1970 TR6C
1972 TR6C
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Re: B40M Roughrider Engine Compatibility
tiger_cub #785297 09/24/19 6:33 am
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Do you want to keep it a B40 or make it a B44.

Re: B40M Roughrider Engine Compatibility
tiger_cub #785299 09/24/19 7:15 am
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Keep it a B40 as I have the barrel & head to suit. How easy would it be to switch to B44 spec - presumably just these parts? Conrod?


1966 Triumph Thunderville
1970 TR6C
1972 TR6C
Re: B40M Roughrider Engine Compatibility
tiger_cub #785300 09/24/19 7:27 am
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B44 has longer stroke so crank including .com rod are out as are pushrods if you want to keep it B40. To make it a B44 the crankcase needs machining to allow higher lift cam, B44 cam and followers, B44 head and barrel, B44 barrel studs modified to fit, oil way changes and no doubt some other details I forgot.

Re: B40M Roughrider Engine Compatibility
tiger_cub #785302 09/24/19 7:31 am
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OK thats great info. I think I can use the conrod with a different crank? Just need to see if one is there, the B44 parts I think include some B40 stuff too, so i might be OK.


1966 Triumph Thunderville
1970 TR6C
1972 TR6C
Re: B40M Roughrider Engine Compatibility
tiger_cub #785304 09/24/19 7:49 am
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The B44 con rod is longer so no use in a B40.

Re: B40M Roughrider Engine Compatibility
tiger_cub #785354 09/24/19 11:03 pm
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All great info, thanks. On another B40WD thread it says to use the B44 big end. So what is the actual conrod length? Asking so I can compare when I see these parts, I don't have any crank at present.


1966 Triumph Thunderville
1970 TR6C
1972 TR6C
Re: B40M Roughrider Engine Compatibility
tiger_cub #785387 09/25/19 6:30 am
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No, the B44 big end refers to the 1/4*1/4 rollers vs the needle roller not the whole assembly, the B40 had both depending on year, B44 had the 1/4*1/4 but it will not for the B40 crank as B44 pin is tapered into flywheel , B40 pin is parallel press fit.

So just get a B40 crank.


Moderated by  Allan G, Jon W. Whitley 

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