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MG MGB GT V8 Factory Originals Technical - 4.6L Rover, things to change

Hi Guys,
I'd like to lean on the experience of this group ! I was going to o Rover 3.9L but, I have been offered a Rover 4.6L block and need to cover the items that I should change for my MGB.
I'm going to source a Rover fuel injection but, I want to stay with a distributor. So, the area I'm focusing on is the Cam, Dizzy and front cover. I believe you can simply change the front cover for a Rover SD1 type and then mount your Dizzy but, I'm unclear about Cam's as the 4.6L doesn't have a drive for the dizzy off the end of the cam. Are there known Cam's out there with this provision that will suit the capacity of the block with the Rover fuel injection ?
Jordan Jones

I purchased my engine from RPI in the UK to put in my 1980 B. The motor came with a cam from a 3.9L and the oilpickup was changed to the earlier style as was the pan. A spacer was suplied for the crank pully as the snout of the crankshaft is longer on the 4.6. When using the older style front cover this is needed.
On the rear of the block a large plug was installed to fill in the hole for the cranshaft speed sensor. This is not used unless you plan to use the GEMS FI. Other than that I think thats all that was changed.

Good luck,

Hi Mike,
Thanks for the response. That's the detail I need. If the crank is longer on the 4.6 how does the adapter fit for the crank pulley and I assume you fit the early pulley ? I'm trying to understand how it makes it shorter. Thanks !
Jordan Jones

It slides over OD at the snout of the crank and fills in the clearance space between the front cover and the pulley. You use the old style pulley and cover. With out the spacer the pulley would not reach the seal in the front cover and oil would be everywhere.
Hope that makes sense.


The early 3.9L engines were equiped with a distributor and the crankshaft oil pump which should fit directly to the 4.6L engine as only the stroke was changed. The water pump has improved flow over the SD1 but uses a serpentine belt and is rev. direction to the SD1. May I suggest you go to Bronte Park on Sept 19th. There is usually 5-6 MGB V8's in attendance including mine, a 3.9L with SD1 timing cover. I still have a 3.9L cover using a distr. If a picture is worth 1000 words, then the seeing the real thing is worth a lot more.
Keith Childs

Thanks, that really clears things up. It will be easier with everything in front of me. So, I guess I'd better go pick this engine up !
I'm going to Stowe for the British Invasion that same weekend so, I won't be able to view your machine (even though I'd love too !) If you have any pic's that yu could email me that would really help.
Thanks again,
Jordan Jones

Hi Jordan
I'll be at Stowe on thge field Sat with my V8 conversion--stop by and say hello!
Its Inca Yellow RB with 302 Ford.
See you there --Gil
Gil Price

Hi Gil,
I'll be sure to do that ! Look forward to hearing the rumble.
My buddy will be bringing his Blaze (orange) factory BGT-V8 which is always fun to see and hear. He will be parked over with the GT class.
Jordan Jones

This thread was discussed between 24/08/2004 and 31/08/2004

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