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MG MGB Technical - MGR V8 manifold holes

I am doing a V8 conversion on an MGB GT , and want to fit RV8 manifolds. Can anyone help with info on where to cut the holes in the inner wings for the manifolds to pass through? What size, and where precisely to cut? Pictures would be helpful too. Thanks

Regards
Steve Lister

Steve,

I got my RV8 system in stainless steel from MGB Hive, beautifully made and price for the complete single box system is £399.00

I will say that only having a rear box was initially ok but after some use it has become excessively loud so am going to fit a centre box, so probably worth going for the two box system.

B Hive supplied a pair of templates for the required apertures in the inner wings, I bought a cheap electric fret saw with metal cutting blades, just marked oy the shape required, drilled some holes as starting points and found that I could get the saw to follow the curved shape then just cleaned up any rough edges with a file.

The B Hive manifolds have to be fitted with the engine out and obviously it's a lot easier to cut the holes without the engine in the way.

I believe Clive Wheatley does a system that has two part manifolds that you can fit with the engine in situ but i think they are more expensive and don't know if he can supply templates for the holes.

Good luck,

Kevin.
Kevin Jackson

Hi Kevin,

Thanks for the info. I did get rough cardboard templates from MGB Hive, but the initial positioning of the template is a bit vague to say the least! i.e I have no reference as to where the front edge of the hole is. If someone can tell me where the front of the hole is in relation to one of the front crossmember bolts for example, then i would have an idea as where to start?

Regards
Steve

Simon

The templates I had fitted up against the footwell boxes on each side and rested on the chassis rail which gives you the position of the holes. I thought the ones I got were a bit vague but they were pretty accurate. Make sure you get them the right way round as one bank of cylinders is slightly forward of the other.

Heres a shot of mine prior to the surgery.

Kevin.

Kevin Jackson

Hi Kevin,

Cheers for the info. It seems that my templates aren't as big as the ones you had. So unfortunately I can't really reference them from the bulkhead. Looking at my templates, it appears that the nearside has a slightly larger and elongated hole. Is that correct? Any chance you would be able to tell me the measurement from the bulhead to the rearmost edges of the holes?

Thanks again for your assistance.

Regards

Steve L
Steve Lister

Steve,

My car is kept at a different address to my home and I won't be able to take any measurements for about 10 days, however here is a shot from the offside front wheelwell which shows the location fairly well.

When I cut the holes the engine was sitting lower and I had a problem with rear exhaust primary flange touching the steering pinion shaft when the engine moved on the mountings. I fitted a spacer between the engine mounting to create more clearance which I would advise you doing as it was needed on most of the V8 cars so my hole looks a little larger than necessary.

Kevin.

Kevin Jackson

Steve,

Here's a link to my car which has a few pics of the cutouts I did:

http://www.britishv8.org/MG/SimonAustin.htm

If you more accuracy, I can take some measurements and some pics inside the wheel arches.

Cheers
Simon
Simon Austin

Hi Folks,

Thanks for the info, pics and links. I will make sure i sort out a spacer for the engine so it doesn't foul the steering.

If someone is able to let me know the measurement from the bulhead to the rearmost edge of the holes when they get the chance? then i should be good to go!

Thanks again.

Regards

Steve L
Steve Lister

I will depend on where you've put the motor, and which headers you are using.
You need to be using standard off the shelf brackets, which not many do, I'm not.
I put the motor in place and lined up the centre of the hole by eye, then cut from the opposite side, the wheel arch using a single fine hacksaw blade. The metal is qite thin and soft and did not take long. I made a small cut with an angle grinder, just to get a starting point. I then went around the edge of the hole a few times with a small shifting spanner, turning it down, belling the hole.
You are quite right, the LHS hole is going to be a little further forward because the #1 cylinder is further forward of #2.
The good news is that the larger the hole, the better the cooling of the engine compartment. I've driven mine over all sorts of muddy roads and never got mud splashing up into the engine compartment. When you are driving along there is quite a vigorous flow of air out of the engine compartment through those holes into the wheel arches.
Peter

Steve

As peter said, the location of theholes will depend on your engine position. Are you using stock MGBV8 mountings? if so your engine will be in the same position as mine.

Re the spacer on the offside, this fits between the rubber mounting and the engine plate which bolts to the block, make sure you havethem the right way round or your engine will want to be in the wrong position.

The spacer is only a large washer approx 1/8" thick, you will be surprised how much this will lift the engine, I didn't think one would be enough so put two in and the engine is now a little high, not going to take one out now as it's a sod of a job once the engines in. Also very important to fit an engine stabilser bar or you will destroy your engine mountings in no time at all and also make sure they are the V8 ones as the standard B ones are not up to the job.
Dave Vale at V8 conversions has the stabiliser and anything else you need and he's cheaper than Clive Wheatley.

Daves in Farnborough Kent near Bromley, where abouts in London are you?

Tel. 01689 858716
Kevin Jackson

If you still have your old stabilizer from the 1800 (that fairly pointless one under the gear box) this fits very neatly across the back of the engine, between the starboard head and the portside foot well, just like Clives does. Could have been made for it, exactly the right length.
You need to bolt or weld a peice of angle iron (shaped as per your own preference)on the top corner of the passenger foot well for the orrigional rubber mount to attach to. It becomes obvious when you trial fit the stabilizer bar.
Peter

Hi Kevin and Peter,

Thanks for the info on the stabiliser. I think I will definitely have to do something about one, or my 4.9 monster will rip the mountings off! Not sure if i have my gearbox one still? Will have to look in the shed. If not, I'm near Watford, so Bromley isn't too far.

Kevin,
Could you possibly email me the pictures that you posted. I had a look at them when i was at work, but when i got home and tried to look at them again, the link didn't work?

Simon,
I see you fitted reinforcement around the holes on your car. Does anyone know if the wing reinforcements are definitely necessary? Has anyone had any problems because they haven't fitted them?

Thanks again

Steve
Steve Lister

Not necessary.
I Belled the hole for appearance sake.
I've seen much bigger holes with no reinforcing at all. These were done by a couple of different professional V8 conversion places.
The first half of the metal above the rail isn't doing much structuraly.
Check local regulations though, I've heard tell that some places require reinforcing, if you cut a hole, no matter if you need it or not. Regulation.
Peter

The metal is pretty thick in this area so I'd have to say that reinforcing isn't an absolute must. I installed them more for appearance-sake. To me, the holes would always look like something was missing if the strips weren't there but Peter's idea of "belling" the edge would look good as well. It's a good "attention-to-detail" feature.
Simon Austin

This thread was discussed between 12/06/2007 and 17/06/2007

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