AC factory records - Did they make mistakes?

[Cargirl]

I am representing an Aceca that plausibly has the correct engine.  The story is below.  How likely is it that the factory made a mistake?  Anyone have any other stories of the factory listing the car engine incorrectly?  Would there be tell tale signs if an engine was changed out for another?

AEX672 is known to have retained its correct AC engine since 1958, numbered CL 2356-W. It should be noted that AC production records of the period were not always strictly accurate, and sometimes changes occurred between the printing of the production records and assembly of each specific car. In this case, AEX661 and AEX672 were built sequentially for export to BC Sports Cars, and the engine present in AEX672 was supposedly intended during production for AEX661. The intervening cars were all Bristol-powered, and AEX661 is presently fitted with a Bristol unit. Since none of the prior owners of either car swapped engines, and it is doubtful that BC Sports Cars swapped engines between the two cars, the engines were most likely installed at the factory in the wrong cars, particularly since “matching numbers” was not such a concern back then. In short, AEX672 was almost certainly born with engine CL 2356-W.

[TTM]

Hello,

The last time I had a look, the Ace & Aceca Bristol registers showed 16 cases of Bristol engines installed in 2 different cars from new, and 2 cases of Bristol engines that somehow each made their way in 2 different cars after they had left the factory. When I mentioned these discrepancies to the registrars I got back a friendly pat in the back for my hard work...

Perhaps the Works were not super strict in their listing, or perhaps some blocks were reprinted deliberately or not with an engine number from another engine believed or not to have vanished or been binned, or else, or perhaps a bit of all those reasons mixed together.

[Cargirl]

So would it help to do a forensic examination on the car?  Would there be tell tale signs in the bay on an engine that has been switched? 

[B.P.Bird]

It would not be conclusive, but certainly persuasive, to check the steering idler. If the chassis had been intended for an A.C. Weller engine then the ball joint in the centre of the three ball joints on the rear end of the idler i.e. closest to the crankshaft damper, would face downward (grease nipple points at the road) whilst the two outer ball joints would face upward (grease nipples point at the sky.) For a Bristol engine all three ball joints face upwards.
You can fit a Bristol engine to an idler intended for the A.C. engine, but the A.C. engine will not fit with an idler intended for the Bristol engine unless you remove the small pulley which drives the fan belt.
Of course you can swop the idlers about as well. The other thing to check, although more difficult to see, are the different arrangements for snubbing engine movement in the chassis. The A.C. engine used a cradle under the gearbox with rubber 'cotton reels' connected to tags on each main chassis tube whilst the Bristol had only one tag on the port side tube. Again these tags could be swopped about, but there might be signs of welds being ground off.
You could look at the wiring loom to see how the dynamo connections are made as the two engines have their dynamos on opposite sides. Same caveat though - looms could be changed.

[Cargirl]

Sorry I should be clear.  The car is actually AEX672 with engine CL 2356-W.  This engine, by factory records, should be in AEX 661. Both car's were delivered at the same time to BC Sports Cars in Canada.  AEX672, according to the register, should have engine CL2362W

So we would be looking at an Ace to Ace engine change.

B.P. Bird the information you just gave is excellent reference material by the way. 

[B.P.Bird]

Sorry I understand now. I suppose each car has a chassis plate and that would shew car number and engine number. Even only one chassis plate would give you the answer. If you make the cars agree with the chassis plate you cannot be wrong and therefore if the Thames Ditton ledger disagrees it must be in error......