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TR7 Modifications and upgrades


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a

Overview of improvement: - 14CUX ‘hotwire’ fuel injection

 

Relative merits: - Increased power and fuel economy, improved cold start performance and reduced emissions

 

Observations: - A donor system from a 3.9 engine was transplanted over by a ‘specialist’ and to ensure clearance between the plenum and the bonnet, spacers were added between the subframe and the chassis. Finding a suitable location for the ECU took a little time and ultimately it ended up with the harness being threaded through the bulkhead and the ECU being mounted on the underside of the glove box.

 

However, bonnet clearance and ECU location were the least of my worries as it became apparent (too late for me) that bolting the bits on is one thing, being able to set it up and fettle it is another. The ‘specialist’ spent ages trying to optimise the system but try as they might, they could not just make the system run reliably. In the end I sought the services of JE Engineering in Coventry who had, as a Rover Group subcontractor, worked on the development of many of the Rover V8 engines and who had much of the original Rover test equipment in their workshop. Several further modifications to the EFI install were required to optimise the system (covered later).

 

Summary: - Once it was running correctly, the difference in performance, economy and general operation over the AFB was superb. However, this is not a 'plug and play' installation and if you are lacking a local 'expert' on the Hotwire system then I urge you to stay on a carburettor- yes you will be down on power and usability but your wallet will be heavier and your hair a little less grey.

 

WARNING: This is not an upgrade to be entrusted to anyone other than a company with a proven track record of installation/set up. Don’t just accept their own rhetoric, get some testimonials!

 

Summary scoring

Safety/security:                N/A

Reliability:                          3

Performance:                    3

Comfort/aesthetics:        N/A

Cost:                                    4

 

PS. Not only did the company that fitted this system fail to fit and fettle it properly, they were also very abusive when I complained. To pour oil on the fire, I discovered that, without my permission, they had taken the car on a 'photo shoot' to generate some publicity shots and furthermore, they are using these pictures on their website without my consent. I have requested that they remove theses shots as their association with my car suggests that I endorse their work which I do not. I would not recommend this company nor would I recommend that they go anywhere near your car.

 

NOTE: Images show a 'before' and 'after' view of the engine bay. 

IMG_2250.JPG

IMG_5016.jpg

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a

Overview of improvement: - Baffled fuel tank and FSE fuel pressure regulator

 

Relative merits: - Consistent delivery of fuel at the optimum pressure

 

Observations: - Once the EFI system was installed it had a number of annoying issues, one being very poor running when the fuel level in the tank dropped below 50%. After some head scratching, S&S Preperations nailed it by highlighting that it was aerated fuel being drawn into the fuel rail that was the problem. Apparently, the EFI system is set up to deliver more fuel to the injector rail than is required during normal operation and the excess fuel is returned to the tank under high pressure and as this fuel re-enters the tank it creates bubbles. When the tank is running lower on fuel, aerated fuel is drawn back through the fuel lines to the injector rail and this in turn creates intermittent rough running. S&S advised on two solutions; either fit a ‘swirl pot’ to the return fuel line to create a low pressure reservoir that empties into the tank or fit a baffled fuel tank to separate the returning fuel from that being drawn out by the fuel pump. I chose the latter option as my tank was as old as the car and would need replacing at some point. It was JE Engineering that advised the fitting of a fuel pressure regulator to smooth out fuel delivery.

 

 

Summary: - You must ensure a constant and consistent delivery of fuel to the fuel rail.

 

Summary scoring

Safety/security:                N/A

Reliability:                          3

Performance:                    1

Comfort/aesthetics:        N/A

Cost:                                    3

 

NOTE: Several years after fitting this tank, it had to be removed and refurbished. The tank had not been vented correctly (by the same company that screwed up the EFI installation) and consequently condensation occurred inside. The tank was removed, repaired and the inside was coated to prevent corrosion

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a

Overview of improvement: - Tornado Power Chip ECU

 

Relative merits: - Improved performance and fuel economy

 

Observations: - Swapping the standard Rover chip for the Tornado unit was straightforward and the engine performance changed noticeably. According to the manufacturer, a 3.5 engine will increase its power output by 10 to 15% and it will give a similar improvement in fuel economy too. I noticed that the engine revved more smoothly and eagerly and the mid range performance of the engine was further improved all of which complimented the upgrades already made to the heads and cam.

 

Summary: - I didn’t notice an improvement in fuel economy but this was because my right foot had mysteriously become much heavier.

 

Summary scoring

Safety/security:                N/A

Reliability:                          N/A

Performance:                    3

Comfort/aesthetics:        N/A

Cost:                                    2

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a

Overview of improvement: - Mallory Unalite distributor, A&R power amp and electronic ignition

 

Relative merits: - Improved combustion and cold weather starting. Compatible with LPG dual fuel systems.

 

Observations: - Upgrading the ignition system at the same time as fitting the EFI was essential. The more precise fuelling provided by EFI along with the increased compression created by the bigger heads meant that a stronger spark would be required to efficiently ignite the mixture so a power amp (which increases spark output by 30%) was fitted. The increase in amperage would quickly destroy standard mechanical points so a photo-optic electronic ignition system was also fitted and to connect the system to the standard plugs, I fitted Magnecor blue HT leads. Finally, I chose a Unalite distributor as I was soon to fit an LPG system to the car and I needed the ability to vary the ignition timing to account for the difference in fuel octane ratings.

 

Summary: - After a few months of operating with this ignition set up, the car was suffering some rough running problems that I personally could not rectify. I put the car into JE Engineering in Coventry (Rover V8 specialists) for them to rectify. Ultimately, they removed the distributor (replacing it with a standard unit), removed the power amp and re-routed the HT leads to eliminate crossover. This cured the problem but left me with having to compromise the ignition timing set up once the LPG system was fitted.

Lots of wasted money for absolutely no benefit.

 

Summary scoring

Safety/security:                N/A

Reliability:                          0

Performance:                    N/A

Comfort/aesthetics:        N/A

Cost:                                    3

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a

Overview of improvement: - Single point LPG

 

Relative merits: - Reduced emissions and reduced fuel costs

 

Observations: - The spare wheel well was removed and a flat floor welded in its place. An 80 litre LPG tank was suspended where the wheel well had been and the fuel line ran along the nearside to a vapourisor mounted on the nearside inner wing. A venturi system was placed just before the inlet to the EFI plenum which is where the LPG was drawn in (fueling was controlled by an ECU that monitored airflow into the plenum and the readings from the EFI Lambda sensor). The ECU itself was attached to the N/S inner wing and always looked like an after thought.

 

I loved the fact that my fuel bill dropped by 40% and because of the mileage I was doing, this paid for the installation in less than two years. However, there were two downsides to a single point LPG system; firstly, the venturi used to jet the fuel into the plenum considerably restricted airflow into the plenum which in turn reduced engine performance on both petrol and LPG. Secondly, as the LPG was mixed with the air in the plenum, there were occasional incidents of the LPG igniting before it entered the combustion chambers which produced lots of noise and smoke and was pretty scary!

 

Summary: - The backfires never caused any damage but they were clearly not safe. I pocketed the fuel savings after the second year to create a fund to upgrade to multi point LPG.

 

Summary scoring

Safety/security:                N/A

Reliability:                          N/A

Performance:                    N/A

Comfort/aesthetics:        N/A

Cost:                                    4

 

PS. This installation was carried out at the same time as the EFi installation and by the same company. Without wanting to repeat myself, you may want to read the associated comments (see post #26)

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a

Overview of improvement: - Multi point LPG

 

Relative merits: - Increased power and reliability

 

Observations: - The switch to multi point injection utilised the tank and fuel lines from the single point system but the multipoint vaporiser (being slightly bulkier than the single point system) was fitted onto the vacant battery housing where it was easily plumbed into the pipework of the heater system. The ECU harness was threaded through the bulkhead so that the box could be mounted alongside the EFI ECU on the underside of the glove box. This arrangement made the installation look far more 'factory OE' than the single point system.

 

Furthermore, as the LPG is injected under pressure sequentially by separate injectors placed in the inlet manifold just before the engine inlet valves there is no risk of a backfire and as the restrictive venturi is removed from the air inlet system the engine performance returned to how it was before the single point upgrade.

 

Summary: - The cost of the multi point put me off buying it in the first place but the single point system was a false economy

 

Summary scoring

Safety/security:                N/A

Reliability:                          4

Performance:                    3

Comfort/aesthetics:        N/A

Cost:                                    4

 

PS. Being disillusioned with the company that installed the single point system, I used an alternative supplier/ installer!

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a

Overview of improvement: - Pacet electric fan

 

Relative merits: - Improved cooling and increased power

 

Observations: - My V8 had been running a viscous coupling fan which ran regardless of whether it was needed and yet on hot summer days stuck in rush hour motorway traffic the temperature gauge would climb dangerously close to the red. Mounting a thermostatically controlled Pacet fan in a 'push' configuration reduced the problem but under bonnet temperatures remained a concern.

 

To further aid cooling I dispensed with using a water/ethylene glycol coolant and adopted the waterless coolant sold by Evans. This gave superior cooling performance across a much wider temperature range and as it boils at 180c it does not pressurise the system (thus reducing operational stress on the cooling system components).

 

Summary: - A quick, easy and effective upgrade but remember to lubricate the fan mounting spindle annually. Mine corroded and failed inside two years.

 

Summary scoring

Safety/security:                N/A

Reliability:                          3

Performance:                    1

Comfort/aesthetics:        N/A

Cost:                                    1

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a

Overview of improvement: LED bulbs

 

Relative merits: - Reduced power demand and increased bulb life

 

Observations: - The replacement of filament bulbs with LEDs was easy and as they give off equivalent illumination with reduced power demands and a life that will outlast the car, the decision to fit them was an easy one

 

Summary: - Fit and forget

 

Summary scoring

Safety/security:                1

Reliability:                          4

Performance:                    N/A

Comfort/aesthetics:        N/A

Cost:                                    1

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a

Overview of improvement: Halogen lighting

 

Relative merits: - Increased field of vision at night

 

Observations: - This upgrade would have been made easier if the designers of the pop up lights had come up with a better method of fixing the rubber surround to the light pod. Taking out the sealed beam unit and popping in the halogen upgrade took five minutes but finding a reliable method of fixing the metal washers to the back of the rubber surround after they came away took ages!

 

Summary: - I could now drive the 7 with confidence irrespective of the time of day.

 

Summary scoring

Safety/security:                4

Reliability:                          N/A

Performance:                    N/A

Comfort/aesthetics:        N/A

Cost:                                    1

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a

Overview of improvement: Central locking

 

Relative merits: - Remote dual locking of both doors

 

Observations: - The theory of the system was that I would never forget to lock the passenger door again. In reality, the upgrade never really worked reliably with the N/S mechanism failing regularly.

 

Summary: - Electrics in a door cavity that is never sealed from the elements is not a good combination and it has put me off fitting electric windows!

 

Summary scoring

Safety/security:                1

Reliability:                          N/A

Performance:                    N/A

Comfort/aesthetics:        N/A

Cost:                                    1

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a

Overview of improvement: Electric boot lock

 

Relative merits: - Unlock the boot from the cabin

 

Observations: - I am not that lazy as to make this upgrade just because it made unlocking the boot easier than it already was! My reasoning was that at the time of fitting it, my car was used as a company car, and it was often left overnight in unsecure public car parks and the big bulky locking mechanism protruding from the boot lid was just shouting ‘break me’ to any opportunist car thief. Fitting the remote boot mechanism enabled me to hide the boot lock behind a Triumph laurel badge (the type that is mounted to the bonnet of a Solihull built car) and still be able to unlock the car from a button hidden in the cabin.

Some years later, I sold the car and its new owner had the boot badge and the underlying locking mechanism removed. The rear panel was reworked so that it gave a flat finished look that differentiated the car still further. A nice improvement.  

 

Summary: - The system has worked very well indeed, the only problem is that if a fuse blows, you can’t open the boot to get your tools out! I now carry a small screwdriver and spare fuses in the glove box.

 

Summary scoring

Safety/security:                4

Reliability:                          N/A

Performance:                    N/A

Comfort/aesthetics:        1

Cost:                                    1

IMG_6583.JPG

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a

Overview of improvement: Category 1 Thatcham alarm and immobiliser

 

Relative merits: - Anti theft

 

Observations: - The system has an array of features including immobiliser (disabling the ignition circuit), pressure sensor (detects the drophead roof being accessed or a window break), vehicle motion detector (the alarm sounds if the car is moved without the ignition circuit being energised) and a cabin movement sensor (detects people reaching into the cabin when the roof is down). All of this is armed from a key fob which also automatically activates the central locking.

 

Summary: - I have never had a false alarm with this system so my neighbours are happy! It is one of those upgrades that you hope you will never have to be used but if it is, you will be glad you have it.

 

Summary scoring

Safety/security:                4

Reliability:                          N/A

Performance:                    N/A

Comfort/aesthetics:        N/A

Cost:                                    2

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a

Overview of improvement: - 15 x 7 wheels running 205/50 tyres

 

Relative merits: - Enabled the fitment of larger front discs and calipers, increased tyre footprint on the road

 

Observations: - The front brakes, mediocre with a standard V8 car, were now way beyond their capabilities with the upgraded TR7. To fit bigger brakes required wheels with a larger ID to accommodate them and as I wanted to keep the car looking as period as possible, I decided against the MGF and other ‘off the shelf’ modern wheels that were available and had a set of replica Wolfrace type slot alloys made.

 

The inner lip of the rear arches were removed to allow unrestricted movement of the wider tyres.

 

Summary: - No noticeable improvement in either dry or fully wet conditions but as with the previous wheel/tyre upgrade, traction and road holding were improved slightly in damp conditions.

Over time, the bespoke wheels became the defining feature of the car and they are often commented upon. I am glad so many other folk like the modification.

 

Summary scoring

Safety/security:                1

Reliability:                          N/A

Performance:                    1

Comfort/aesthetics:        N/A

Cost:                                    4

 

NOTE: Hi-Spec specified that the Monster 4 300mm disc and caliper set that were to be fitted had to be under a 16 inch rim as a minimum due to the clearances required. I did not want to fit 16 inch wheels as I think they make the car look too modern. Hi-Spec provided me with a set of drawings that gave the dimensions of the brake components and from this I deduced that it should all fit under a set of 15 inch wheels (if the wheels were custom made to my specifications). I produced the rudimentary drawing as shown below and gave them to the wheel manufacturer who made the wheels against a non refundable order. I am no draughtsman nor engineer but I trusted my schoolboy maths, placed the order and held my breath. Thankfully, everything fitted and with enough clearance to enable efficient cooling too!

IMG_65951.jpg

IMG_6593.JPG

Wheel.jpg

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a

Overview of improvement: - Enlarged outer front hub bearings

 

Relative merits: - Increased operational life and improved reliability on longer runs

 

Observations: - The outer front hub bearings were adequate for a 2 litre car in standard trim back in the 1970’s but the 15,000 miles my modified TR7V8 covers in modern traffic every year means that the bearings now operate beyond their design limits. On two separate occasions whilst travelling for several hundred miles at high speed on hot summer days, the front bearings began to rumble before eventually giving up completely. Rather than wait for another disintegration to occur, I decided to err on the side of caution and engineer out this propensity for failure. A pair of modified hubs, purchased from the USA, did away with the original bearings replacing them with the larger bearings from a Triumph GT6.

 

Summary: - 10,000 spirited miles passed without incident then a nasty wheel vibration manifested itself. Removing the outer bearing revealed that the n/s shim used to increase the o/d of the stub axle was no longer held firm by the Loctite Threadlock. The assembly was cleaned and reassembled and a higher grade of Threadlock was used to reattach the shim and since then, I have had no re occurrence of the problem.

An observation is that subsequent to the upgrade, several MOT inspections have given an advisory regarding 'slight play' in the wheel bearings. They have never led to a failure. 

 

Summary scoring

Safety/security:                N/A

Reliability:                          3

Performance:                    N/A

Comfort/aesthetics:        N/A

Cost:                                    2

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Overview of improvement: - Hi Spec performance brake conversion with red stuff pads

 

Relative merits: - Eliminate brake fade and increase braking capacity

 

Observations: - Bringing the car to a safe halt from motorway speeds and eliminating brake fade were critically important now that the car was not only more powerful but also more competent through the twisty stuff. I elected to fit a set of Hi Spec Monster 4 calipers and two piece 300mm discs as it increased the surface area of the pistons by 10%, doubled the pad surface area and considerably reduced front end unsprung weight.

 

Furthermore, this upgrade changed the brake balance to almost the ideal 69/31 front to rear and the brake torque was sufficient to not only stop the car within a safe distance but also relative to the modern cars we now share the roads with! (see post #82 for the maths).

 

One really annoying problem with the discs however was that there was quite a bit of run out which manifested itself as a vibration through the steering under braking. I found a local company that used the Pro Cut computerised disc skimming system and I had them skim both discs and the difference is astounding! No matter what speed I brake from the steering wheel stays as steady as a rock; no wobbles, no shakes and zero vibration.

 

To get an idea of how the process works then you can see it happening to my car in the you tube video (you can clearly see the high and low points on the disc as it rotates. The operator ran a further two passes to take out the imperfections). The other link takes you to the companies website which also has some useful information too.

 

http://youtu.be/8_IazzhN8Ow

 

https://brakelathe.co.uk/why-skim-discs/drivers/

 

Summary: - Once the disc run out was fixed, these brakes delivered just what I wanted, fantastic stopping power and zero brake fade. However, the brake peddle remained long on the first depression and despite further bleeding and a change of the seals in the master cylinder, the problem remained. Before I rushed out and purchased an upgraded master cylinder I spoke with the owner of a track car that used Hi Spec Monster 4 brakes and he gave me a hint which fixed the problem.

 

The Monster 4 calipers have two bleed nipples (top and bottom) that are there for no other reason than to reduce manufacturing costs for Hi Spec (it saves them having to produce a left and right hand caliper). First of all bleed the front n/s brake via the top nipple and then remove the caliper, invert it and clamp the caliper back onto the disc and re-bleed via the 'new' top nipple (it previously was the bottom one before you inverted the caliper). Then refit the caliper the right way up and bleed again via the top nipple. Repeat this process for the offside front.

 

I found that although it made for a slightly tedious process, the outcome was just what I wanted, a rock solid brake peddle!

 

Summary scoring

Safety/security:                4

Reliability:                          4

Performance:                    4

Comfort/aesthetics:        N/A

Cost:                                    4

IMG_1360.jpg

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a

Overview of improvement: - S&S adjustable front suspension struts

 

Relative merits: - Adjustable front ride height

 

Observations: - Fitting the strut top bearings had given the car a slight 'nose up stance' and this combined with further planned front end weight reductions meant that I needed to design in an element of front end ride height adjustment. Initially I was tempted to fit adjustable 'coil over dampers' to not only enable fettling of the ride height but to also reduce unsprung weight but in the end, S&S persuaded me to fit their adjustable front strut. It was the right decision as I never intended to race my car and so the added expense of the 'coil overs' was unnecessary.

 

Summary: - The front end now sits much lower to the ground improving aesthetics and in combination with the rally spoiler, reduces front end lift at high speed, (NB. the rally spoiler was found to reduce front end lift by up to 30% by BL Motorsport during testing at MIRA; https://www.triumphwedgeowners.org/uploads/3/0/4/2/3042952/_blmotorsportmemo1980.pdf

 

Summary scoring

Safety/security:                1

Reliability:                          N/A

Performance:                    1

Comfort/aesthetics:        1

Cost:                                    2

 

NOTE: Photo is of car with lowered front suspension

Modified.jpg

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Overview of improvement: - Quaife R380 5 speed gearbox

 

Relative merits: - Increased torque capacity

 

Observations: - The standard fit LT77 gearbox had sprung an oil leak and the teeth had become worn on second and third resulting in it regularly slipping out of gear. Researching the history of the LT77 it became apparent that it was never designed to cope with torque in excess of 250lb/ft (even in a lightweight car) and with a larger capacity short block planned, I decided to upgrade to the LT77's successor, the R380. This unit has the same bell housing as the LT77, very similar gear ratios, almost the same dimensions (the gear change extension does need shortening), synchromesh on all gears and above all, a torque capacity rating in excess of 300lb/ft.

 

Summary: - The positives are that I now have a gearbox that is fit for purpose and the driving experience is good with a closer gate and a smooth gear change, (baulking when engaging reverse, first or second when cold is a thing of the past). One downside is that when the gear change extension was shortened, so too was the gearstick centralising spring and shortening the spring has reduced its effectiveness which has resulted in the stick failing to centralise as it should. I hope to find a spring manufacturer who can make a new one from scratch to eliminate this frustrating little problem, (see post 60 for an update).

 

One other additional issue that needs to be sorted is that the speedo is now reading 25% less than actual road speed. I guess this is no surprise considering that the gearbox ratios, differential ratio and road wheel circumference have all changed from standard.

 

Summary scoring

Safety/security:                N/A

Reliability:                          4

Performance:                    N/A

Comfort/aesthetics:        2

Cost:                                    4

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Overview of improvement: - Quaife R380 5 speed gearbox

... The box was sourced and fitted by S&S Preparations and despite it being their first, they report that all went well.

Aha, so it was for your gearbox swap Richard called me and checked on my experience...

Yes, R380 is THE way to go! [The fifth gear is a little lower at 0.77:1 ] Interesting to know the swap went well.

 

synchromesh on all gears

Yes, for some reason they've even included synchromesh on the reverse...

 

The only downside is that when the gear change extension was shortened, so too was the gearstick centralising spring and shortening the spring has reduced its effectiveness which has resulted in the stick failing to centralise as it should. I hope to find a spring manufacturer who can make a new one from scratch to eliminate this frustrating little problem.

Strange comment/behaviour.

Back when I did this swap I had the extension shortened (article on it published in a TR Driver Magazine some years back) and did not have to shorten the spring - so no problems with its (or any other) function...

Gearlever_extension-72.jpg

[btw. I used a gear shift 'knob' from a '98 Escort - with the correct gear position mimic AND a great ergonomical 'feel'...]

TR8-R380_Gearlever_ext.jpg

 

How did you get over the longer gear selector mech on the R380 out of intrest.

As I wrote above it's been explained in an old TRD Magazine.

Not problematic at all, just a question of an elaborate Z-formed cut-and-shut operation. And some wizardry aluminium welding skills...

R380forTR8-small.jpg

Cheers,

/Odd

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Hi,

 

Good to see you 'over here Odd ' Did your prop require any attention ie. shorten ?

 

And some wizardry aluminium welding skills...

 

 

There in would lie a problem for most of us ;) Steel not a proble but alluminium a skill for sure.

 

Unfortunatley not the most common gearbox in the world either but at a guess easier than a T5 swap.

 

Cheers John

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Did your prop shaft require any attention ie. shorten ?

No...

But some material were needed to be taken off of the front edge of the rear transmission mount bracket:

Bracketcutout.jpg

 

There in would lie a problem for most of us. Steel not a problem but aluminium a skill for sure.

I outsourced this welding job.

Bought it fully commercially from an engineering, fabrication and construction company actually. Wasn't cheap, but well worth the cost. I then could use the bracket without ANY further work or adjustments after the welding was done. Not even a hint of warping, he was a true wizard...

Weldingwizard.jpg

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Update on R380 Gearbox

 

Having spoken with S&S they have confirmed that their installation utilised a straight cut through the remote extension (and not a 'Z' cut) which removed one of the spring mounts and shortened the spring length. The cutting and welding of the spring has reduced the torsion within it and as the spring is now only located at one mounting point it is pivoting when the gear stick is moved from side to side.

 

S&S have confirmed they will remake a new extension utilising the 'Z' cut thus keeping the full length spring. I will update the summary on the R380 installation when I have installed the new component.

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Overview of improvement: - S&S Universal Joint Propshaft

 

Relative merits: - Increased torque capacity

 

Observations: - The only weak link in the transmission was now the original CV type propshaft which complained every time it was asked to transmit extremes of torque, particularly at low speeds and high revs.

 

Summary: - The whole transmission set up now works smoothly and quietly.

 

Summary scoring

Safety/security:                N/A

Reliability:                          1

Performance:                    1

Comfort/aesthetics:        N/A

Cost:                                    2

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Overview of improvement: - Enlarged EFI plenum and air intake trumpets

 

Relative merits: - Increased torque and BHP

 

Observations: - To adequately feed the big valve heads with enough air and in readiness for the short motor upgrade, the standard Hotwire throttle body/plenum was bored out to a diameter of 70mm (standard is 65mm) , 45mm bore inlet trumpets were fitted (38mm standard) and the inlet manifold and heads were matched and ported. I also took this opportunity to have the Idle Air Control Valve (or stepper motor) relocated from the bulkhead side of the plenum to a new mounting position on the offside face of the plenum thus allowing the fitment of the fresh air scoop back onto the car.

 

Summary: - The extra volume of air gave an improvement in performance at the bottom end of the rev range but the real difference was at the top- it never runs out of breath! However, after a while I became aware of misfires when under load at high revs and after seeking advice, I changed the spark plugs to a set that would work under higher compression and with higher octane fuel (LPG is 110 versus Shell V-Power at 99). The V8 now runs B7ECS plugs from NGK which is a 'cooler' plug and this has cured the problem.

 

 

Summary scoring

Safety/security:                N/A

Reliability:                          N/A

Performance:                    4

Comfort/aesthetics:        2

Cost:                                    4

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... I also took this opportunity to have the Idle Air Control Valve (or stepper motor) relocated

from the bulkhead side of the plenum to a new mounting position on the offside face of the plenum

thus allowing the fitment of the fresh air scoop back onto the car.

It would be nice to see a picture of your stepper motor move, just to compare it with how I fitted mine back in 2007...:

idleairvalve.jpg

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