The Fairwater Collection !

An MGBGTV8 Sebring and some interesting Land Rover conversions.
Now, see also my professional site at: www.met-alchemy.com !

Winter 2008/9 Underside detailing and a nice exhaust system. Why a V8 sounds so great!

Well the summer was rotten and autumn didn't really exist.  Now it seems we are straight into Winter.  Work cannot stop just because it is Winter though.  That is the sort of thing which leads to SADS, frustration and too much stress and telly.  One has to have an escape route. 

Back in late August I made the momentous decision to get a big tent to house the thing in, and I found a cheapo marquee which would take the MG and the Land Rover too as a bonus.  I strapped it down with ground anchors and ratchet straps.

I hate dark evenings, and this marquee would, (if it lasts the gales, and so far so good, courtesy of the ratchet straps), enable me to use these rotten dark evenings to advantage, even if only for a short time, and for short periods, and also I don't have to worry about it raining and having everything uncovered with tools all over the place.  If I can get out there for half an hour to contemplate over a cup of tea, that will help enormously.  As we British say, if all else fails, make some tea.

In the white tent, with a strip light on a tripod, it is really great inside there!

Below, taken 21st October 2008

 

Time to start to get some of the plumbing back on to the underside, while it is still easy.

Some details then.

The finished repositioned filler hole in the boot floor. Seams and rivets were subsequently painted over again with more yellow.

On with the tank then.  It was painted yellow too, as it is visible underneath from the back and will give the impression of being an under valance of sorts.  The tank is an RV8 one which has the fuel feed coming out of the tank sender, a fuel return on top of the tank, and four tank vents from the top, seen here going four into two, angling up towards the boot floor.  These go to a charcoal cartridge in the boot of the RV8, and this will need to be  modded for this application.  The RV8 efi pump and two filters are seen lined up on the outside of the battery cage.  Later, these were moved to the inside of the cage.

Inside the boot, the filler looks like this.  The original hole is visible to the right, and various surface rusting is evident on the inside face of the floor.  It isn't too bad though.  The RV8 tank has a straight pipe up from the tank as opposed to the normal MGB one, as we can see here.  This is actually fortuitous as I have found that by utilising the angled part taken from a scrap tank stuck into the rubber pipe shown, at the right angle, this will connect to the original filler quite nicely.

 

On with the plumbing. Pics taken 16th November 2008.

New battery cables in left hand cage, with cut out switch in heel board.  Efi pump and filters  now inside right hand cage.

New brake flexi.  New 8mm copper feed and return fuel pipes and brake pipe.  Original loom bound with spiral binding.  Pipes fixed to original studs with P clips and stainless nylocks. 

New battery terminals and isolator switch, sealed with seam sealer.  Conduit over tunnel for battery cables.

Original fixings for new brake, fuel and battery cables.  Original rubbers had an extra space which the fuel return now goes through. 

A new battery earth cable which will run directly to the starter motor for maximum starting efficiency is routed through the hole in the cross member which has been enlarged and tubed to seal it and to take both the battery earth cable and the loom.  The high current starter motor is taken care of with heavy copper cable in both directions.  The general vehicle electrics of far lesser drain will be served by a separate earth strap from the engine to the chassis.  Doing this is a bit of a luxury, but a V8 does need a good current flow to the starter.  It's probably unnecessary on an 1800cc engine.

Detail of tube through crossmember.  It's a  length of plastic cable conduit.  A splash of black chassis paint protects the bare metal around the enlarged hole until it is sealed with seam sealer and yellow paint applied over this.

Front end showing fuel pipes going up the tunnel to the engine bay.

Detail showing P clips holding fuel pipes in position. The pipes are first fitted with short lengths of rubber fuel pipe to act as mounting grommets.  The lengths of rubber tube are split along their length and pushed over the pipe.  8mm fuel hose has roughly half inch outside diameter, and the P clips are 12mm.

 

The Piece de Resistance

In coating the underbody purely in paint, whatever the quality of the paint, in use, there are bound to be stones flying which will chip the paint.  Obviously this is not acceptable as it will just start rusting out again at the chips. It is therefore imperative that the paint finish is protected.  Before undertaking the painting, much thought was given to this problem.

I think I have found the answer.  It comes in the form of clear liquid rubber called Plastidip.  It will be applied in thick layers to act as underseal and should give exceptional chip resistance.  If it does pierce in exceptional circumstances, the paint should stand up, but anyway, there will hopefully be an opportunity to reapply a new layer before the paint becomes compromised.

Winter Inaction

Well after brushing some Plastidip on, towards the end of November, the weather went cold, and stayed cold until January, so there was no hope of finishing the Plastidip applications.  Virtually nothing has been done up to the middle of January, and it now seems that unless some reasonable mild days are had, not much will be done before Spring.  We will see. 

At the very end of November, frustration led me to do one chore, and that was to prep the rear springs for refitting, and to remove the original rubber bushes which were somewhat worse for wear.  This was done but firstly cutting the overlapping edges off from the rubber all around one end of the bush, so as to expose the steel outer tube.  The reason for this was so that a socket of suitable size could then be introduced into the spring eye to bear on the bush tube and used as a drift.  A lump hammer on this socket fairly rapidly removed both bushes.  The spring eye was supported on a solid piece of steel (flatbottom rail), for good support.

29th November 2008.  Rubber before cutting, and looking rather saggy.

 

The outer bush tube can now be seen and in fact in this picture it has already been partly driven out with the adjacent socket and hammer.

 


I have to admit that December and January beat me and I just could not bring myself to do anything outside.  Both months were very cold and it just seemed too masochistic to do anything involving standing round getting cold feet.  I metaphorically had cold feet on the whole thing and just put it away out of  my mind as best as I could. Towards the end of January though, I did manage to get some more Plastidipping done on the underside.  In the picture below, at the end of January, with the aid of a heat lamp, which was quite effective.

25th January 2009


It turned out that enough warm spells were had during a generally cold and miserable February, to finish the Plastidipping with three coats plus a gloss coat over them, while at the same time, some of the steel fittings were cleaned down and painted in chassis paint.  The heater box was done, and treated to a new element and foam sealings, the pedal box, cover, and washer bottle holder were also all attended to with a number of coats of chassis paint.


Next the springs were painted in chassis paint and the original part numbers refreshed in white.  The lettering was painted in Plastidip for protection.

18th March 2009


Then the rear axle was given a second coat of duck egg blue Hard Top Flexi.

The charcoal cannister which connects to the RV8 tank and on the RV8 resides on the rear of the boot inside the car, could not be fitted inside practically, of the GT body.  After some thought it was mounted outside underneath in between the battery cages, where it should be out of the way.  It was well painted in chassis black.

Studs shown here fitted through from the top.  The hex heads live in the central ridge of the battery cover, so do not get in the way of its fitting,

And there it is fitted.  The pipes are directed around where the diff will sit and hopefully they will miss it.  8mm pipe fits the connectors just nicely.

By the middle of March we were enjoying a week of warm ish sunny weather and so I took advantage of the first opportunity to bask in some warm sunshine while contemplating the next moves.  It was becoming apparent that before long I would be running out of work to do with the car on its side.  I had to make sure though that everything which could be done in this position, was done, as being spoilt working on the bottom of the car from a standing position, working with it right way up was going to be difficult!

I therefore decided to try to sort out the exhaust as much as possible and so the first step was to mark out and cut the holes for the RV8 manifolds in the inner wings.  The templates for the holes were supplied by the MGBHive and with blind belief, I just marked the hole and cut them out with lots of hope and not much second thought.  I put all my trust in the MGBHive and hoped they were right.  I had no other option.  Time will tell how good the holes will be, but it did allow me to line up roughly the manifold pipes and this was critical in finishing the rear end.

I cut out the holes with my air saw which is more like a jigsaw than the sabre saw, and has narrow fine toothed blades which will turn sharp corners.  I did not have to drill any starter holes as the cut was started on the ridge shown in the picture.  The whole thing dropped out as one tight fitting undistorted section which in theory could be refitted pretty easily.  I had considered cutting the hole slightly smaller and swaging the sides over to provide strength, but in cutting the hole, it is apparent that there is plenty of stiffness in the inner wing as it is.  I therefore did not bother.

18th March 2009


The rear pipes were going to be twin pipes with inline and tail cherry bombs.  I have heard many exhausts fitted to V8's over the years, and nothing compares to the Cherry Bomb for out and out V8 sound track.  Being a total connoisseur of the V8 sound track, only the best sound will do.  With inline and tail bombs, the sound volume is pretty well controlled, especially on a twin pipe system.

Knowing pretty well how the rear pipes were going to look, I thought hard about mounting brackets and rubbers.  I eventually decided to use Land Rover Defender type rubber ring hangers on self fabricated brackets.  I thus made up some fittings and brackets out of mild steel strip and dunked these in chassis paint.  The results can be seen here, as well as the trial fitting of both rear systems with suitably bent connecting pipes.  This has enabled me to determine how the rear pipes will be connected to the manifolds.  Twin separate systems with an H balance pipe were considered, but it was decided after much thought that it would be easier to utilise the supplied siamese and then fabricate a Y and spreader pipes from this, basically making a classic crossover system.  This is underway at the end of March, just as we come into Spring at last.

Left is the rear bracket.  One assembled and one parts only without the rubber.  On the right are the centre brackets.  Again one in parts and one assembled with the rubber.

29th March 2009


Centre bracket fitted and with additional strap bracket fitted for rigidity.  (Not yet dipped.)  Simple angle fitted to lower end of rubber, screwed to clamp.


The connecting pipe is bent so as to angle the rear end down under the axle. (Hopefully).


Rear end bracket.


Finally, just to finish off the winter section, and because it follows on, the final piece of exhaust was ordered from a custom exhaust manufacturer after having measured up and drawn out a scale diagram of the piece required. Details of the exhaust manufacturer are in the links section.  This is the Y piece and spreader pipes to connect the manifold siamese to the tail sections.  It looks really good in its trial set up below, together with the manifolds fitted in their approximate positions.  This is all very pleasing and is another milestone reached.  I think we are now ready to turn the car the right way round again and embark upon the 2009 season of finishing the mechanicals and getting it back on its wheels again.

I have some concerns over the proximity of the pipework to the electrics and fuel lines.  However, the pipes will be lagged with heat wrap when finally fitted, so heat problems should be avoided.


One might ask some questions regarding this arrangement, which may seem either a compromise or unduly complicated according to your viewpoint. 

First, why not have completely separate and simple straight systems running each side?

Second, when you do have separate systems, why is it recommended to have a connecting "balance pipe" joining the two systems together making for an H like pipe arrangement?

And thirdly why do as I do here, and take the two systems together only to split them apart into two again?

On the MG, two separate systems would be possible with the RV8 manifolds coming through the inner wings, as these could be altered to go straight backwards. As I say, the manifolds would need altering to take the inward angle off them at the bottom, and the thing then is that a balance pipe would need to be provided somehow.  There is quite a distance between the two pipes, and the balance pipe would have to go under the engine and gearbox.  Jointing up such an arrangement is a bit messy, but a piece of small diameter flexi pipe would work ok as it would be easier to connect or disconnect.

The alternative is to make the arrangement I have used.  While it uses the standard manifold and front pipes unaltered, this arrangement is not merely a compromise to allow this, or  just a means of getting through the centre crossmember using the built in cut out, so there is no decreasing of ground clearance.  These certainly are advantages however. 

The siamese and Y splitter actually form a crossover pipe, which is used on a good many standard performance V8 installations especially in the US, and is supposed to be a better performing arrangement than a H pipe, due to its scavenging capabilities.

Why have any link between the two systems?  Why not have twin unlinked pipes?

It is a fact that V8's run better and produce more power and torque with an H pipe or a crossover pipe, than they do without any link between two separate systems.  The reason for this is tied up in how the engine works.  To be exact, the firing order and resultant pressure waves.

It is easy really when you think about it. 

The firing order is 18436572.  Analyse this giving consideration to which banks the cylinders are in, left or right, and you see this, as below.  Running from left to right, the top line is the right hand bank and the bottom line is the left hand bank, if you are looking at the engine from the top, with the front to the left and the rear to the right:


                                                                                                                                   8  4         6                  2

                                                                                                   1              3            5  7


This shows that there is first a left bank fire, then two right bank fires in succession, then a left, a right then two lefts and finally a right.  Thus in one full firing sequence there is a time when there is twice the load on the right bank system and one time when there is twice the load on the left bank system, due to two cylinders firing in quick succession rather than alternately with the opposite bank, as is the case for the remainder of the firing cycle.  This produces one high pressure wave in each side system in each full cycle of firing. These pressure waves make for uneven running when using separate systems, and the pressure waves can hold back the following pressure pulse due to slowing of the gases from the lesser following pulse, as they are not purged effectively, 

However, these pressure pulses happen at a time when pressure is at its least in the opposite system.  Thus a  pressure balance can be achieved by a connection between the two systems, which, twice in the firing order, will allow gas to expand into the opposite system, first one way, then the other.  The advantage of the crossover pipe arrangement over the H arrangement is that there is positive scavenging of the opposite system in the crossover, due to its design, which causes the "filter pump" effect.

It is this mismatching of pressure waves from each cylinder bank which produces the typical and wonderful syncopated sound so synonymous with the V8 engine, and it is this process which has to be exploited and managed in order to maximise the sound track and obtain the maximum smiles per gallon.