Mystery engine

[TR7V8mike]

Hi,

 

I'd be grateful for some help in identifying my engine. The engine number is on a flange on the rear left of the block (see photo) and is 42516115 and the CR is 10.5:1. This tallies with the tables Rimmer Bros put out and identifies the engine as a 1967-1976 3.5L, originally in an automatic P6 Rover.

 

The issue is that my engine does not have the tab on the deck of the block that sticks out between cylinders 3 and 5, where the engine number usually lives. Folks on other forums have never seen this before. Does it tell me something more about the origins of my engine? Does it tell me that the engine is extremely rare and worth a small fortune?

 

I look forward to your answers.

 

Mike

[Ragtag]

I don't think I have ever had a V8 without the engine number 'plinth'. I suppose the question is whether it isn't there because it has been ground off or because the web was not cast in the first place. I would find the latter surprising but that may just be because my experience is flawed.

 

I assume you want to know to ensure you buy correct replacement parts.

 

So far as I remember the P6 blocks had rope oil seals on the crank (front and rear) but the late ones may have had plastic as they overlapped SD1 production. They also had short water pump shafts. The distributor shaft had an end like a flat blade screwdriver which located into the end of the oil pump shaft. Later this arrangement was reversed but not sure when,

 

Your rocker covers aren't P6 but could have been changed at a later date.

[AnthonyF]

If you read the Rimmers V8 engine info it does mention that some early engines only had the engine number on the bell housing flange at the rear of the block. So I wouldn't stop buying the lottery tickets just yet

[TR7V8mike]

If you read the Rimmers V8 engine info it does mention that some early engines only had the engine number on the bell housing flange at the rear of the block. So I wouldn't stop buying the lottery tickets just yet

Thanks Anthony. Is there anything I need to know about the construction of this particular version of the engine or is this a minor detail I can ignore?

 

Mike

[Alec Pringle]

Hi Mike,

 

if I recall correctly the change from tabless to tabbed deck came in 1970 - introduction of the Mk2 P6 and revisions similarly to the P5B, although I don't think the latter was acknowledged as a Mk2 . . . . that's long before the 1973 change from the 'rope seal', incidentally.

 

Suggest you consult a parts book for the P6 to check chapter and verse on the differences of Mk1 and Mk2 3500 engines, let alone those of '73 onwards, and bear in mind also that the P5B 3.5 engine is not exactly the same as the P6 version . . . .

 

It was alleged back in the day that at least some of the reliability problems for which the P5B/P6 V8 saloons were notorious could be attributed to carelessness in Rover stores and on the line - incorrect parts fitted for the particular variant, all too easy to transpose similar but different components.

 

Those early engines with flange numbering are now rare, in the sense that relatively few P5B or P6 V8s of 1970 or earlier remain, and any that were utilised in subsequent more sporting applications blew up long ago . . . . later V8s were rather better !

 

Cheers

 

Alec

[Ragtag]

if I recall correctly the change from tabless to tabbed deck came in 1970 - introduction of the Mk2 P6 and revisions similarly to the P5B, although I don't think the latter was acknowledged as a Mk2 . . . . that's long before the 1973 change from the 'rope seal', incidentally.

 

 

That would explain why I have never seen one without the tab as all my V8's were post '72. Mind you my last P6 had rope oil seals and whilst I can't recall the Reg, I'm sure it was '75 or '76 vintage.

[TR7V8mike]

Thanks Alec, that really helpful to know when I start making some mods. Not quite sure how I feel about having one of the few engines that hasn't blown up (yet).

[Alec Pringle]

Hi Mike,

 

there were two problems with the earlier engines that tended to result in premature demise. Bear in mind also that they were intended for luxury saloon cars, with automatic gearboxes (an effective rev limiter!), not for road burning sports cars . . . .

 

One, these early engines did not take kindly to being over-revved, and yet the average V8 conversion enthusiast inevitably regarded the red line on the tacho as a challenge - and paid the price.

 

Two, the engines were prone to oil 'sludging up' and the consequent lack of lubrication at high revs doomed the lump . . . . Hence the specified 3K mile oil changes, and if that regime was not adhered to the engine life would be limited, camshafts were particularly notorious for rapid failure. Even with 3K oil changes, a proper flush every 12K was advisable.

 

Modern oils are of course much better at resisting sludge formation, even so you need to be conscientious and change oil regularly and flush periodically on the traditional basis of time and/or mileage.

 

Cheers

 

Alec

 

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