Hi all
I was wondering if anyone has experience of running older B25 cams with newer crankshafts.
Camshafts can have up to three timing marks and RR recommends use of the "V" mark if one is present. This mark appears to be two teeth anticlockwise from the straight "I" timing mark with the third "." two teeth clockwise from the "I" mark. I assume that these three marks relate to the different models and years where the same camshaft was used but different amounts of advance/retard was used???
The camshafts I have have the single "I" mark, so my question is, can I retime the camshaft two teeth anticlockwise to coincide with the "V" location on my earlier cam???
Secondly, the engine I am rebuilding has a later crankshaft in ( lefthand flywheel drilled for timing plunger, after 69??), are there any differences between the later and earlier type crankshafts ie was the location of the woodruff key for the timing pinion moved in relation to TDC.
Hope this all makes sense.
Any info would be greatly appreciated.
Regards
Rob
The cams and cranks are entirely separate issues so not related.
With the cams, verify the tooth to use for timing by positioning the crank at tdc.
In that position fit the cam so both cam followers are slightly and equally raised.
In that position the tooth on the camwheel to use for timing is the one at 12'o clock.
If 12 o' clock falls between two teeth use the tooth looking clockwise from the 12 'o'clock position as this advances the timing and gives better performance at higher revs. Conversely, using the nearest tooth anti-clockwise retards the timing and gives better performance at low revs. Your call.
The B25 crankshafts are all identical in terms of the key ways/timing plug/rotor position/timing marks.
Due to modern fuels burning at a different rate to those which were around when BSA produced timing figures, use the original timing marks for initial starting/setting up only.
With the engine running, adjust the timing to find the position on which the engine runs happiest I.e. fastest at tickover.
RR
I am on holiday at the moment and don't have access to reference data for the but I am sure the valve timing for the B25 models did not change across the years. In other words, the extra timing marks on later camshaft pinions weren't added because the valve timing had been changed for a particular model.
It is probably safest to use matching crankshafts and camshafts but, if not available, I would personally use a timing disk to make sure the valve timing was correct.