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MG MGB GT V8 Factory Originals Technical - Apparent benefits of RV8 header system

Yesterday removed both block hugger headers. Using supplied reinforcement frames as template, cut hole in left wheel arch, seam welded frame and fitted Clive Wheatly header. Removed starter motor and steering rack to facilitate removal of right header. Fitting of new right header is today.

Perceived benefits so far - fitting of header is now a complete breeze as the nuts can be tightened up through the wheel arch. Also it has become clear that future header work will not require removal of starter and rack ever again!!! I would say that just for this, an RV8 header conversion is worth carrying out. There is lots of clearance from the 7" wheels (someone expressed concern about this in the archive).
Also, my starter will no longer be subject to direct heat ( I have already had to replace one before I beefed up the heat shield)

Today, cut and weld reinforcement frame to right side, replace rack and starter, fit header, re-route brake pipes - I imagine that these will have to exit forwards and follow the front cross-member. (If anyone could confirm this quickly, I'd be grateful) The RV8 manual suggests this although the diagram is very poor. Finally I have to prepare to sell very cheap used header wrapped in heat insulation (as per ad in classifieds)
Marc Gander

I've just ordered up some of Clives manifolds. You mentioned reinforcement frames, do these come with or do I need to ask for/buy them?. Was intending to make my own but it would be nice if they came gratis.

You have to order them separately. I had first thought that I would make up my own but I decided at the last moment that I would save myself the trouble. I'm glad I did. It would have been very trickly finding out the correct shape of the holes and making up the frame without an existing template.
It really made the job an awful lot easier. They are quite expensive but believe me, they are worth every penny. They are a one-off, once in place they don't wear out and I looked inside the bonnet of an RV8 this morning and I was extremely pleased to see that my conversion looked pretty well identical - not quite as neat but very good indeed. Don't forget that the frames are not just 2 dimensional. They are contoured and reinforced with their own lips. Bite the bullet on this one - believe me.

Also check the number of supplied clamps. Clive's clamps are excellent but you need 7 and he only supplied me with 6. I haven't spoken with him yet but you should query how many there are in his kit. If he says 6 then you will need to order an extra one.
Also, order his gaskets as they look as if the are particularly good.

Yesterday we cut the second hole and welded the right hand frame into place and fitted the header. It looks very nice indeed and a trial fitting of the rest of the exhaust system showed that it will all fit very well indeed. The starter motor and rack had to be removed and replaced after removal of the block hugger - but that is the last time. Yippee! Once again, access through the wheel arch made fitting of the new header so easy that I thought that I might take it off and refit it again just for a laugh.
Now the brake pipes have to be re-routed. I saw that the RV8 has a rigid pipe crossing from the calliper to the front of the wheel arch and the flexible hose takes off from a bracket forwards opf the steering with the pipework following the line of the front cross member. This will be done on Tuesday evening. It also looks that there will be enough room to refit my plastic wheel arch guards with a littl cutting to clear the exhausts comfortably which is excellent news. I have had plastic arches on this car since 1986 and they have protected the car very well. In fact the underseal on the inside of the wing appeared to be in almost new condition after 16 years.

I am planning to make a thin steel shroud on each side to give the brake pipe at the calliper a little more protection from the heat.

I did notice that the new exhaust will pass directly underneath the clutch slave cylinder and only about 2" away. I shall fit a steel plate shield as I figure that the heat exposure will reduce the life of the seals quite significantly.
Marc Gander

Is anyone aware of a U.S. supplier of the reinforcement flanges? Is there a web page for Clive Wheatly.

I'm not aware that Clive knows about email. Also I should say that getting him to return messages left on his answerphone is a bit of work too and I found that the best thing was not to depend on him getting back to me but to make sure that I kept trying to contact him until I succeeded. On the other hand he is very knowledgable, was prepared to spend quite a lot of time explaining things and was very reliable in terms of getting orders out quickly.

I think that the reinforcement frames may be standard RV8 parts. They certainly came in plastic bags marked "Heritage".

By the way, I forgot to mention that getting the right hand header in did entail removing part of the brake master cylinder although it wasn't necessary to undo the pipes.
Marc Gander

I have a set of Clive's RV8 stainless steel headers. The quality is top notch, excellent welds and fit.
I had heard that Dan at D+D was going to start selling some of Clive's parts in the U.S. I'm not sure if that has happened though.
Gordon, Clive did supply me with a card board template for the cut outs, I made my own plates off the templates.

bill jacobson

Check the British V8 Newsletter for suppliers of MGBV8 conversion parts.
Martyn Harvey

Ring him direct
Clive Wheatley on (your dialling code for the UK) 1902 330489 or 1902 337294. I called and placed an order and he rang back (this is to Australia remember) within an hour with details as to cost of getting gear to me.
(Allow for time zones of course)

Thanks to all for the information. I'll call Clive early tomorrow morning (local). I just received a new set of RV8 headers today from D&D. While they look very nice, they're not stainless steel, so I doubt they are supplied by Clive Wheatley. The build quality looks very good, though. After I've fit the entire system, I'll remove it and have it all ceramic coated. These manifolds are just too expensive to let rust out.


Got the car started last night.

We realised that the original plan for re-routing the brake pipes wouldn't work. We hadn't appreciated that the RV8 callipers are mounted on the fron of the disk.

Instead we drilled a hole about 1.5" in-board of the existing mounting flexible hose mounting bracket which is welded on the cross-member just under the damper. This allowed the flexible hose to be moved further away from the header. The copper pipe was then routed around the back of the damper and along the front of the cross-member. A small heat guard which will separate the flexible hose from the header will provide additional comfort.
The only last problem was that when we unscrewed the flexible hose from the left-hand newly re-conditioned Princess Calliper, we found that the installer had cross threaded the flexy nozzle into the calliper and it was only with some work that we managed to clear the thread so that it could take a new flexible hose. Regular visitors to this Board will know immediately which company carried out the re-conditioning and installation of this brake system. Another incident in an incredible catalogue of sloppy or highly questionable work. Newcomers may wish to consult the archive for more information.

I'm not going to have time to finish off the detail and give the car a drive until next week and I'll report on the apparent benefits of actually using the system then.
Marc Gander

Today I re-fitted one of the plastic wheelarches. It went in very well with a bit of modification to clear the exit hole in the wheel arch. They were easy to modify using a pair of sharp kitchen scissors. I cut the plastic so that it was about 1" clear of the hole and then screwed it into place. I must say that I was quite anxious that the heat of the headers might melt the plastic or maybe even ignite it. In fact although it does get very hot it doesn't melt at all although one can detect a certain pliability if one pushes one fingers into the plastic when the car has been standing at tick-over for 15 minutes or so.
As a final test, I took a piece of the discarded plastic and held it directly against the header. Although it did start to melt fairly quickly, it produced no smoke, no particular fumes and certainly was nowhere near to catching fire. I measured up some cardboard templates in order to cut some 1mm stainless steel heatshields to protect the brake pipes. In fact these are probably not necessary but I shall fit them anyway as I expect that at least constant exposure to these temperature will accelerate the deterioration of seals and fluid.
While I had my head stuck inside the wheel arch and the engine running, the fans suddenly came on. There was an immediate and massive current of very hot air coming out from the wheelarch holes. This must mean a substantial reduction in under-bonnet temperature at least through better circulation, not to mention the fact that nearly half of the exhaust system is now outside the engine bay.

Having fitted one wheel arch, I took the car out for it's first real drive. Not motorway but fast urban roads. No noticeable reduction in cabin temperatures but engine temperature was generally about 2 or 3 degrees centigrade lower than usual even though today has been a pretty hot day. I would say that acceleration was noticeably much faster than before - and the car was already very quick. (the ports are now perfectly matched to the header).

A fair amount of queueing in traffic produced no rise in engine temperature at all.
At the end of the run, although wheel arches and brake pipes were hot, I didn't feel that they had suffered the kinds of temeratures which should cause any immediate concern. However, as I have said, I intend to take precautions
I shall take it onto the motorway in a couple of days and see what difference there is at high speeds.

I suppose that with the new exhaust system in place the engine is now a bit out of tune. I notice misfiring at tickover and for the first 200 or so revs of acceleration before the engine smooths out and then accelerates very smoothly and powerfully.
On overrunn I notice a small amount of popping and backfiring which never occurred before. It obviously needs a little tweaking.
Marc Gander

Hey Peter,
I have a set of RV8 manifolds from a company in Melbourne, MG Workshops and I'm having trouble fitting them to insure adequate brake/trye clearance. Do you know of this company and have you seen their manifolds? I am concerned that the manifolds are not correct and I am also not impressed with the quality of their construction.

Also have you investigated the an engineers opinon of the RV8 routed exhaust? I have heard bad rumors that some don't like the set up, crazy if they actually understood the benefits of the system.

I think that I'll be getting a set of reinforcement frames as a template to help align the holes in the inner wings, I did not know that these were available.

Clem Spriggs

Spriggsie . . . I ordered wing reinforcements for that same reason. They're a bit pricy with freight, but worth it in my opinion. The reinforcements are contoured to fit correctly only in one fashion, so it takes the guess work out of laying out the holes. The reinforcements I got are Heritage parts (I got mine at B Hive in England), and there is a widened area at the top of the part that will allow you to enlarge the hole enough to get the headers on without removing rocker covers or lifting the engine. I cut the holes with a 3" cutoff wheel on a die grinder without removing the engine. As far as the engineers opinion . . let them do a conversion and come up with a better solution. The RV8 style is an effecient design. The only drawbacks I'm concerned with are a weakening of the inner wing structure (seems OK on the RV8) and the fact that any tubular manifold generates more underhood heat.


DO use the reinforcement frames as a hole template but DON'T use them as a positioning guide. Every engine is positioned slightly differently. Measure carefully to discover the correct positioning and then you will have to bend the frames into place as it is likely that they won't match the contours of your engine bay exactly. Do appreciate that the holes are not cut central to the engine but about 1" towards the rear.

Also you will find that in some places the frame does not lie completely flat against the side of the engine bay. There may be a 1/16" or so gap. I checked an RV8 and found that it had exactly the same gap. This comforted me that I was doing the right job although whether MG/Rover put the gap there for sound engineering reasons or because it simply turned out that way is a matter of conjecture!
Marc Gander

It's a very simple matter to hold the manifold above each head and visualize the center of the exit pipe. That will verify the position of your reinforcement doubler. No big deal.


Took the car out today to try the exhaust system on the motorway. Short bursts of 120Mph. Sustained 100-110. Car performed very well. Engine temperature constant 87C. Some rises in heavy traffic to 91C. Sustained travelling at 50-60mph - 86C.
I haven't tried any of the higher 140-150mph speeds yet but certainly I would judge that the modification has been a success. The engine definitely needs tuning as it is very lumpy until about 2000 revs. My guess is that the timimg needs to be retarded slightly. The engine ticks over a little fast and only really becomes smooth over 2000rpm. Anyway, I'm very pleased so far and I hope that the account that I have given on this thread helps anyone else who is planning the same thing.

A final unexpected bonus - since putting in the V8 I had always been trouble by a serious vibration/knocking coming in about 90mph and not disappearing until about 110mph. I had dismissed the possiblity of the engine hitting the car body as there seemed to be far too much clearance. However, I have spent a lot of time and some money trying to disover the cause.
I must have been wrong because the knocking has gone and the car is extremely smooth.
Marc Gander

I know MG work shops quite well, they are just around the corner from me. They are a reasnably large operation down in North road East Bentley. I nearly bought a set of their manifilds myself, before I settled on Clives more expensive ones. I believe that they (MG W'S)are getting them made by Cuz'n'Co MG. up in the Wimmera (not sure of this though). I will foreward the Email they sent, with pictures , so you can compare, see if there are any radical faults/differences. However give MG workshops a call because they will exchange goods.... if pressed. They are a reputable operation but you do need to have some ready answers so anticipate their questions (have you got them on the right way round/sides etc..)

Spriggsie - I have 7" wheels on my car with ET30. I estimate about 4" (a small fist) clearance between my headers and the tyre on full lock. RV8 with 8" wheels is slightly less. Are your wheels standard and if not what size are they? My headers come into the wheel arch and drop down parallel to the car body with less than an inch clearance of the body. RV8 similar. If your dimensions differ much from these, then you might be able to decide if the problem is caused by your wheels or by a difference in the shape of the headers.
Marc Gander

Also re: exhaust . I was told the exact opposite, that engineers don't like the blockhugging style and prefer RV8 style, somthing about proximity to brake lines. In fact as I now recall it was Mathew at MG workshops who told me this when showing me those manifolds, hmmm. Whatever the opinion, RV8 style has set the precident and already has approval so it should just be a rubber stamp job for the engineer or they had better have a good reason why. Possibly establish initial contact with the one of the approved engineers processing the appropriate rubber stamp (Phone Queensland road authority and they should give you a list to choose from) . Tell him what you're doing and ask advice, however do remember to use the key phrase "just like the Rover MG RV8" allot.
With respect to brake lines, if exhaust proximity turns out to be a problem I was thinking of going though the guards (separate from the exhausts of course, with small rubber plugs). My '83 SUBARU does this so it must be OK. Be interested to hear what your engineer says though.

Routing brake lines directly through the guards sounds OK but I would still be worried about exposure to heat. Although there there is proximity between the pipes and header in the area of the wishbone, routing the pipework forward removes most of the system from the heat source as per RV8. Taking the pipes diretly through the guard will result in a certain continuity of proximity to the heat source and this doesn't make me feel comfortable. I think that it is a good idea to get the plumbing away from the heat source as quickly as possible so that there is less likely to be an accumulation of heat within the fluid.
Marc Gander

from what I've been able to gather the RV8 runs the 'passenger side' brake line along the front crossmember, true?. This would also imply that the drivers side brake line also approaches the wheel from the front rather than the rear. In other words (in case I'm not being clear,which I'm probably not) The brake lines go forward (from the master) to the cross member then back to the wheels. It this is so I might try it (when I get to that stage) as it should be cheap enough to do, and easier than rerouting lines across the front bulkhead.

Yup, on my car pipes on both sides were run forward behind the shock and then into the bay with the passenger side running the length of the cross-member. It just seemed most sensible and straightforward to follow the RV8 route - not because it was maybe the best route but because it is tried and tested. The reduced heat benefit was very clearly a desirable advantage.
Marc Gander

This thread was discussed between 19/05/2002 and 03/06/2002

MG MGB GT V8 Factory Originals Technical index

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