Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB GT V8 Factory Originals Technical - ALternate SU HIF 6 V8 manifold

There is a manifold conversion for MGB V8s that uses the original Rover twin SU (with pent-roof tower) manifold, but utilizes special cast aluminium runners to locate the SU carbuerttors to the back of the engine. I first saw this in Roger Williams book on converting an MGB to V8 power and agin on another website.

While I know the Weber (Carter) 4 bbl carb is better, I am looking to create a different (and more British) look to my conversion.

Does anyone know who manufactures this cast aluminum runners to fit the standard Rover (P5, P6 and SD1) manifold?

Robert Northrup

Hi Rob,

Your std manifold will have to be machined to fit the carb. inlets supplied by Clive Wheatley from England(see

Rgds Trevor Burnett
t burnett

Give Clive a ring on; UK (44)(0)1952 710810.
He has them cast for him.
Allan Reeling

Thanks all for the input. But not wanting to belabor the point, I'm away of the original B GT V8 "claw" manifold. I do not want that.

Rather, someone has produced castings for two manifold "runners" that attach to the Rover P5, P6, SD1 twin SU manifold (with that little "pyramid" tower onto which the carbs are mounted) and run to the back of the motor. The SU HIF 6 carbs are then mounted to the runners, similar to the B GT V8. The carbs are spaced more widely than with the claw.

This system was featured (without identifying the manufacturer) in Roger Williams "How to Give Your MGB V8 Power" book. And recently on another site I saw photos of Richard Day's V8 conversion with said manifold.

The original "claw" system is fine for 137 bhp, but has problems with even fuel distribution in higher output motors (try 240).

I don't want to go the Carter-Edelbrock-Weber route (space limitations and I hate 4 bbl carbs). Nor the Holly 390 cfm (tricky to tune and a bitch to work on, although it's a drag racer's delight). And no FI. I hate working on those (most recently modifying a C4 Corvette. Never again). I want something that is British and traditional..

This So, if anyone out there has a lead, please let me know.


Robert Northrup

I think the ones in Roger's book were "one-off" cast items, but i've also seen a similar fabricated design used. Go see a foundary or a sheet metal fabricater, the latter will be the cheapest!
Allan Reeling


As suggested you could get them made in steel tube with suitable flanges to bolt on to the SD1 manifold.

If your looking for 240 BHP from a 3.5 your going to struggle using 1 3/4" SU's, your also going to need a good pair of heads and a decent cam to get near that level of power.
For engine advice if you need it have a look at The V8 Forum.

Kevin Jackson


PS. Also do not use block hugger manifolds as these are very restrictive, the RV8 style Stainless steel manifolds/system from B Hive is good value for money and will flow well enough for your potential power output.

Kevin Jackson

Kevin,not related to this site but what rear shocks are you using?
Rgds Trevor
t burnett


I have Monroe telescopics that were part of the original Moss Hopkinson handling kit.

They are excellent but could not see a part number when I had them off when fitting the new springs.

Moss might be able to quote a part number, but buy them from the states they will be a lot cheaper.

Kevin Jackson


Apologies for addressing you as Alan!

I also note you are in Texas and the B Hive I was referring to are in the UK not the US one.

Fortunately for you most of the tuning parts for Rover V8 engines are US sourced and a lot cheaper over on your side.

TA Performance do a lot of small block Buick/Rover parts and will have available soon their own heads for the Rover V8.

British and MG Experience are also both good forums on your side of the water.

Kevin Jackson

To Trevor, Alan, Kevin, et al...

Many thanks for all of your collective inputs.

First I appologize for the sloppy spelling/typing (keystroking nowadays!). But as an advertising copywriter in my former life, spelling wasn't that important -- I had proofreaders to back me up! Now, I am getting too old for this!

Second, I will certainly use the RV8 style headers to keep under-bonnet temperatures down...and increase power. Rover were very smart to go this route...

Regarding Manifold: I'm sure I could fabricate my own "external" manifold runners for the Rover P6 et al manifold, but why reinvent the wheel? I guess I'll have to.

An Offenhauser/Edelbrock manifold with Carter/Edelbrock/Weber 4 choke carb would be easier, but too "hot roddy" for me. I'm looking to build what I envision as a proper "British" job as it could have been done by BMC if the conditions had been right. Besides, I can adjust SUs very easily. I'm lost on a Carter.

Further, the B GT V8 manifold with "claw" serious issues (according to Dan LaGrou and others)with fuel distribution in higher output V8s -- some cylinders run lean, others rich. The Rover version is a little more "open" in the way the fuel gets to the manifold's runners.

Massaging the internals of the Rover manifold (using the Extrude Hone tm process) can open the runners up even more.

Regarding SU HIF carbs with 1.75 in. chokes: Of course, when I want the flow data (cfm) on the SU HIF 6 carbs from Burlen Fuel Services I can't find it!

But as I remember, with the two carbs it equalled a little over 300 cfm. Not much by today's standards. But a company in California specializing in tuning SUs for racing, etc. are able to add another 50 or so cfm per carb -- so 425 cfm total flow is obtainable. And plenty for an engine in the state of tune I am building.

So, there you have it.

Let me know if any of you need research done here in the States for your projects. Would be happy to help.

Robert Northrup


I understand what your trying to do but an Edelbrock/Carter (basically the same carb) is a very easy to set up for the Rover V8.

By the time you have gone to all the hastle and cost of having the SU's modified and the manifold extrude honed it would probably be cheaper to buy, certainly in the US, an Edelbrock Performer manifold and 500 carb, if you want 240 BHP you would also be better off looking for a 3.9 engine and with a decent pair of big valve heads and possibly a Crower 50232 cam which would get you right into the 240BHP area with good on road drivability.

Just my thoughts.

Kevin Jackson


Thanks so much for your insights. As for engine size, a very popular conversion here in the States is to use a Buick 300 cu. in. crankshaft in the 215 (Rover 3.5 L) block. These are still very plentiful and D&D Fabrications has built hundreds of these engines. As a "stoker" motor, it'll have a lot more torque.

D&D are also expert in porting the 215's heads and installing larger valves. Roller rocker arms and lifters (tappets in the UK?) are also available for this engine over here.

Yes, the Carter/Edelbrock/Weber is the easiest route to high horsepower. But I'd rather go with a British solution as I think it be more in character with the car as well as the fact that I know and work with SU carbs. The Carter is actually foreign to me!

I've resigned myself to the fact that I'll probably have to fabricate the intake runners myself, but that shouldn't be too difficult.

I was only trying to save myself the trouble.



Robert Northrup


Yes, familiar with D & D excellent source of parts and knowledge on your side of the water.

I understand D & D quite like the Crower 50232 cam which is the one i chose for my 4.35 engine.

I'm still running in but the initial impressions are very good, it will cruise along at 35 MPH in direct top gear with a 3.08 diff at approx 1500 RPM and pull away smoothly, drop it down to second and give it a bootfull and wow, sorry officer!

Good luck with your project.

Kevin Jackson

This thread was discussed between 17/06/2009 and 30/06/2009

MG MGB GT V8 Factory Originals Technical index

This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.