B21 timing chest

[Greenfield]

The restoration of my B21 continues. Inside the timing chest, the timing gear plate has a bronze bush which doesn't have a shaft running through it. Is this correct?
Behind it is a nut with locking washer that sits proud and causes the plate to rock slightly. The nut has chewed the inner side of the bush. Something is not quite as it should be. Any advice would be appreciated.

[militaryron]

Unfamiliar territory again for me! What sort of oil pump does a B21 have? On the B30's and M20's that I've rebuilt. The bronze bush on the timing gear support plate is there to support the end of the crankshaft. The worm drive for the oil pump is between the timing pinion and the support plate??? I'm at a loss with what you have I'm afraid. Ron

[Steve.S]

Like Ron, I don't know much about these machines, but my guess would be that the crankshaft nut is not the correct part, being too thick.
You could either heavily chamfer, or preferably shorten the nut. Your plate then won't wobble, and the nut should clear the bush.
It seems that the male part of the  timing cover fits inside the bush, and this will supply oil to he crankshaft, so the Parts Book may show a felt seal to prevent oil leaking into the timing chest, although it may just rely on a close fit to achieve sealing.
Do let us know how you get on with this and your other problems.
I'm sure Ron would agree that a response is always helpful. 

[Greenfield]

After a cup of tea and returning to the problem, I discovered that the tab washer was bent around the nut but was loose. I removed the nut to see what was going on. The photo shows the chewed tab washer (there is nowhere to locate a tab on the shaft so it was doing nothing) and the incorrect nut.
According to the parts book, the timing pinion, serrated washer and half nut should be identical to those fitted to my B33. So, although things looked ok superficially and corresponded to the picture in Haycraft, the nut was too high and interfered with the timing plate bush. If I now fit the correct washer and shave down the nut, hopefully the problem should be sorted.
Thanks for your input
Paul

[Steve.S]

Paul,
I do hope I'm not confusing the issue here, but according to the Parts Books, the timing gear support plate was not fitted until 1939, and then only to the B21 De Luxe model, not the Standard model. When fitted, the timing gear is similar to the one Ron depicts, i.e with an extension. I imagine that this means that the De Luxe mainshaft is longer than the Standard model?
Clearly, your cam spindles are threaded to accept the support plate bolts, (or perhaps just for extraction) but I wonder if someone has tried to modify your earlier engine to include the support plate? I note the Haycroft picture is of the Standard model without the Support Plate.
The point here is that it is essential that there is some sort of seal between the timing cover and the crankshaft to allow oil to enter the crankshaft from the timing cover under pressure. So it seems to me that with the Support Plate fitted, the whole arrangement is the same as the M20, which Ron can expand on.
By the way, do you have issues 151 to 157 of RealClassic Magazine. They contain articles covering the restoration of a B21, but unfortunately not the engine.
 I hope I'm not leading you up the garden path here.

[chapmast]

It looks like you have an earlier crankshaft fitted into a pair of 1939 crankcases.

I have a number of these engines and in 1939 the crankcases were heavily modified so that they could adopt the same timing gears as the post war B/M series, hence the out rigger plate was introduced. The crankshaft pinion is extended into the outrigger as can be seen in Ron's set of pictures. Referring to Pauls Black and White picture, which is of the earlier model, it can be seen that the cams are completely different. The later crankshaft has a longer timing side shaft which resembles that of a B31/B33. The drive side crankcase is also different from the earlier models in that they will accept the post war primary chain cases. I have a feeling that the Drive side of the crankshaft will also be different.

[chapmast]

Further to my previous answer, Paul's point about seal between the timing cover and the crankshaft isn't an issue as the 1939 model retained the oil feed to the big end via the timing side bush i.e. the 1939 crankshaft is not end fed.

[Group Leader]

I'm certainly no expert but have learnt a lot rebuilding my '39 deluxe model ......

The first photograph shows what it looked like originally with the static cam axles and the (very sensible) fixed outer support plate and the oil pump drive retaining nut with a shoulder that ran (I think, I can't really remember) in the bearing.   

Unfortunately you may recall that a PO had completely mullered the timing side casting and I was unable to find the required replacement so an earlier B21 standard case had to be substituted which has the live cam axles supported in the timing cover and no support plate.    The end of the crankshaft is not supported in the earlier standard engines and whirls around in the fresh air of the timing cover.   The older style cams are seen in the second photograph.     

The really Eagled Eye Expert observers will also note the later and incorrect mag idler gear still in use.   This is because the earlier, thinner, timed breather idlers seem to be rarer than the proverbial output from a rocking horse.      The replacement casting had to be modified to use the later idler stub axle thus dispensing with the timed breather (the original crankcase breather on the drive side is still there and in operation!) .   The older style timing cover shown in Photo #3 had to be modified to accommodate the thicker, later idler by machining off some of the projection on the inside of the cover.     It will be noted that there is no crankshaft bearing support in the cover between the two cam bearings.

I hope that is of interest if not use!

Alan