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Wales
by Joske Vermeule, September 1
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Jun 14th, 2026
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Joined: Feb 2012
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Charter Member
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Charter Member
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From a recently produced book:  June 1997 Dealer Notice: "As it has not been possible to obtain the current Range Rover 4.6 litre engine, due to supply problems with Rover and because of the modifications required for installation, we have arranged for a special engine to be prepared. This uses the current 3.9 litre engine, but built using the standard 4.6 litre block. This involves stripping a new engine, removing the block, specially modifying a 4.6 litre block to accept the front cover, and rebuilding the engine. This produces a special unit using largely standard Rover parts. The distributor set-up is largely the same as 3.9, as is the camshaft and ECU. The block is cross bolted for strength. The crank, pistons and block are standard Range Rover 4.6". Cricky i didnt know that took place
Martin (Deano)
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Joined: Dec 2008
Posts: 22,370 Likes: 354
Roadster Guru Member of the Inner Circle
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Roadster Guru Member of the Inner Circle
Joined: Dec 2008
Posts: 22,370 Likes: 354 |
Morgan fiited the 3.9 between june 1990 and 1997 after which the 4.6 was fitted. I book does not quote the switch over month. But the 3.9 was also available from 1997!! Does that mean it continued along side the 4.6 as an option? It seems so because most post 97 Plus 8's are not 4.6. I think the 4.6 was extra cost. The 3.9 certainly continued to appear in the brochures. Often described as 4.0 litre.
DaveW
'05 Red Roadster S1
'16 Yellow (Not the only) Narrow AR GDI Plus 4
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Joined: Aug 2017
Posts: 310 Likes: 9
Learner Plates Off!
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Learner Plates Off!
Joined: Aug 2017
Posts: 310 Likes: 9 |
The engine numbers were probably not sequential as my March 1994 3.9 has the engine number 47A01975A. Thats a big jump from A019 to A289 in a few months!
Colin G P
1994 +8, BMW Calypso Red.
2002 4/4, 4 seater, BMW Calypso Red.
How do you open the boot?
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Joined: May 2015
Posts: 110
L - Learner Plates On
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L - Learner Plates On
Joined: May 2015
Posts: 110 |
“The 3.9 certainly continued to appear in the brochures. Often described as 4.0 litre”
The 4.0 litre engine is also called the GEMs engine.
The 3.9 and 4.0 have the same bore and stroke, the 4.0 block has cross bolted mains.
The 3.9 front case has a distributor and oil pump driven from the camshaft.
The 4.0 does not have a distributor, the oil pump is crank driven, consequently the crank has a greater overall length, the ancillaries are driven from a serpentine belt, thus these parts aren’t individually interchangeable.
Naturally enough, interim engines exist with both distributors and crank driven oil pumps!
The Des Hammill book “How to power tune Rover V8 engines” is an excellent source of information and will talk you through the variations, [whereas the 2x David Hardcastle books are better suited to mopping up spilt oil].
As noted above the MMC 4.6s were in effect big bore 3.9s with 3.9 distributors, heads and injection system. At the time the factory was using a 3.9 & 4.6 engine to produce one 4.6; zero miled 3.9 short blocks were available as spare parts from MMC and jolly good value they were.
Last edited by Horror; 08/02/18 09:45 PM. Reason: Fat fingers
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Joined: Sep 2014
Posts: 2,272 Likes: 7
Talk Morgan Expert
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Talk Morgan Expert
Joined: Sep 2014
Posts: 2,272 Likes: 7 |
Mine is a 1999 3.9 with original engine 47A0707B. It seems a digit short but that's what is in the registration book. My 1999 car has the original engine number 47A09915B, so yes, yours do seem to be a digit short. It looks to me like it should be 47A09707B. Easy enough to check, it should be stamped on the right hand bank cylinder head where the compression ratio is also found.
Andy G
1999 +8 , Indigo Blue.
Ex-John McKecknie/Mike Duncan 1955 +4 racer.
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Tricky Dicky Member of the Inner Circle
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Tricky Dicky Member of the Inner Circle
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Posts: 37,469 Likes: 988 |
Mine is a 1999 3.9 with original engine 47A0707B. It seems a digit short but that's what is in the registration book. My 1999 car has the original engine number 47A09915B, so yes, yours do seem to be a digit short. It looks to me like it should be 47A09707B. Easy enough to check, it should be stamped on the right hand bank cylinder head where the compression ratio is also found. Thanks for that, I'll check that out.
2009 4/4 Sport Henrietta
1999 Indigo Blue +8
2009 4/4 Sport Green prev
1993 Con Green +8 prev
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Joined: Mar 2016
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Talk Morgan Regular
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OP
Talk Morgan Regular
Joined: Mar 2016
Posts: 844 |
Got this from Morgan today...
"Thank you for your recent e-mail which has been passed to me in the Morgan archives. I have checked the factory records but cannot find 47A04702B, however we did fit engine number 47A04701B into chassis number R11501 which was completed & test driven during the week beginning 3rd May 1996 and despatched from the factory on 13th June 1996. It is possible that 47A04702B was one of a batch of engines supplied to the Morgan factory and held as a spare, but I can find no record of it."
Hmmmm, close but no cigar......
Simon
Series 1 Aero 8
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Joined: Dec 2008
Posts: 22,370 Likes: 354
Roadster Guru Member of the Inner Circle
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Roadster Guru Member of the Inner Circle
Joined: Dec 2008
Posts: 22,370 Likes: 354 |
The good news is you had an answer.
Being Morgan, the facts are elusive.
DaveW
'05 Red Roadster S1
'16 Yellow (Not the only) Narrow AR GDI Plus 4
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Joined: Aug 2017
Posts: 310 Likes: 9
Learner Plates Off!
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Learner Plates Off!
Joined: Aug 2017
Posts: 310 Likes: 9 |
The 3.9 lit V8 had the 'hotwire' petrol injection system. The distributor did not have a traditional contact breaker: a sensor triggered the spark. With the 4.0 lit engine, I think Rover had moved on to the 'GEMS' injection system with no need for a distributor.
1994 +8, BMW Calypso Red.
2002 4/4, 4 seater, BMW Calypso Red.
How do you open the boot?
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Talk Morgan Regular
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Talk Morgan Regular
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Been in touch with several Rover V8 specialist, buy nobody is able to give me a definitive answer!
Series 1 Aero 8
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