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Finding engine ID

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twas_brillig

Jedi Knight
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I went out to find my engine ID this evening (BJ7); the firewall plate provides the VIN but advises all and sundry to look at the engine for its identifier. I looked and didn't find; suggestions as to what to look for (I presume one of those slim metal strips?) and where?
Thanks,
Doug
 
In this picture, the engine i.d. tag would be just behind the waterpump inlet, and below the #1 exhaust port.

There's a flat ledge, so if there's no tag, it was likely removed/destroyed (they melted in the caustic solution used to boil out the blocks) during a rebuild.

IMG_1428.sized.jpg
 
Thanks guys - sure a lot easier when you know where to look. And it appears that I'm a genuine 29F /BU/H577.
However - the whole purpose of this exercise was to find out what the gear ratios were so I can calculate speeds vs. tach readings, and Haynes advises that the ratios changed at engine no. 10897 (with overdrive) - which doesn't seem to match what I've got.
Any suggestions as to what the Haynes manual is talking about? My Bentley/shop manual is loaned out, so can't check there.
Thanks,
Doug
 
Doug,

Attached are the speed / gear ratio charts for both for 22% and 28% overdrives.
Hope this helps!

Duane
58 BN6
 

Attachments

  • 22242.pdf
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While a little harder to find, I believe the actual tooth count (pinion/ring gears) is stamped on the removeable portion of the axle assembly__the differential.

I'm still 300 miles from home, but we're headed in that direction, so maybe I can get a picture later this evening.

In the meantime, I can tell you where to look, and you might get lucky! Look where the bearing retaining cap studs protrude through the case (facing forward).
 
Randy is correct (As always!)

Attached are the pictures he was referring to: the ratio stamped on the ring gear and the ratio stamped on the case, which should match unless the ring and pinion have been changed.
 

Attachments

  • 22247.pdf
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There were two differential ratios used on 3000s: 3.909 for a car equipped with overdrive, and 3.545 for non-overdrive. The 3.909 had 11 pinion teeth and 43 crown wheel teeth (43/11 = 3.909, although it is stamped on the diff 11/43), which is what the numbers are that are stamped on the differential in the photo posted by Duane. The 3.545 had 11 pinion teeth and 39 crown wheel teeth (39/11 = 3.545).
When a BJ7 engine was to be mated with an overdrive gearbox, its serial number included an "R", which signified Laycock de Normanville overdrive: e.g., 29F/RU/H577. If the engine was to be mated to a non-overdrive gearbox, the "R" was omitted: 29F/U/H577.
I have no clue how Haynes came up with the engine number 10897 "with overdrive". There is no such change point specified in the BMC BJ7 and BJ8 parts manual -- either for engine, gearbox, or rear axle. Also, the "overdrive" and "non-overdrive" engine serial numbers did not fall in such a neat sequence.
As mentioned, engine serial number plates will dissolve in hot tank chemcals, but they can be removd to prevent that. Once the plate is gone, there is absolutely no way to positively identify that engine anymore.
 
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