GrahamB

I have no extra non return valve in the system, only the one incorporated in the connector at the servo end. Interestingly, this is a right angle connector , the same as the spare one that you received. I know that the valve works as you can actuate the brake pedal a few times with the engine stopped and feel, and hear, the servo operating. As you can see in the photo, the lowest point in the vacuum hose is where it rests on the rocker cover, after which it rises steeply to the servo. This has to serve as the U tube fluid trap and has not caused any problems over the years it has been fitted. After replacing the front brake callipers, it felt as though the system was not correctly bled. I thought that it was air in the servo unit so removed it from the circuit. Thanks to an item on the forum, I realised that it was because of the incorrect seal design. I used a reversed sash clamp between the brake pedal and the steering wheel to keep the system pressurised for a couple of days to "stretch" the seals and the system started to work satisfactorily. I therefore re-configured the hydraulics to bring the servo back into operation and noticed a significant improvement in that with the servo, I no longer had to brace myself against the seat in order to generate enough pressure to obtain the required retardation.

I have attached a copy of the instructions that I received with my servo. I have also attached a photo of my engine bay which shows, although not very clearly, the servo mounted next to the clutch master cylinder. The original brake pipe was just bent round to fit into the outlet of the servo and a short new pipe made up to connect the master cylinder to the servo. I hope that these are of some use. brake_servo.pdf

Alternatively, keep the 6volt ballasted system and run a separate switched 12 volt supply, from a green or white wire, to the electronic module. That is how my Pertronix system works. I have also included an in-line 5 amp fuse tucked up behind the dash. Removal of the fuse then immobilises the car, just remember to replace the fuse before trying to drive off otherwise you can be sat there for ages wondering why it will not start. (How do I know?)

There is a special high resistance wire which I believe is pink/white that runs from the ignition switch to the coil. There is no separate ballast resistor. I was told never to run the alternator without the connection to the battery or the electronics may be damaged. Both large terminals should be at battery voltage. The smaller terminal should be at basically 0 volts but rise to 12 volts as the alternator charges the battery.

I changed mine to Historic when we moved house. My wife's modern registration document came back within a few days. After a couple of weeks, they returned the build certificate which I had sent to prove date of manufacture. Nothing happened for another couple of weeks so I made enquiries. They claimed that they had no records of my application even though they had returned the certificate. Time to start worrying. After another few days the completed amended registration document arrived. From this I concluded that DVLA seem to be efficient at everyday requests but anything out of the ordinary such as changing to Historic seems to cause them problems.

Studs that fit into aluminium casings are usually UNC, to give a stronger hold into the relatively soft metal, with a UNF end onto which the steel nut is fitted. If the stud fits into a steel casing, it is usually UNF at both ends.

With a 3.98 diff for every 3000revs in top gear, the wheels will revolve 771 times. Assuming a rolling circumference of 6 feet, the car will travel 1542 yards or 0.876 miles. So at 3000 rpm the car will travel at 52.6 mph giving a overall gearing of 17.5 mph / 1000rpm. With a 3.65 diff the wheels will revolve 3000/3.65 = 822 times and the car will travel 1644 yards or 0.934 miles. So at 3000rpm the car will travel at 56 mph giving an overall gearing of 18.7 mph/1000rpm. Therefore changing from the intended Dolomite diff to a Spitfire will cause the speedo to under-read . To correct the reading, assuming it was correct in the first place, you need to multiply the mph by a factor of 1.066 I knew that the A level in maths and mechanics would come in useful one day !

In response to Mathew's photo, ARP is the manufacturer and T is the tensile designation. I cannot find the definitive specification for T grade but I think it is 55-60 tons/sq inch which equates to 85-93 kg/sq mm. If I needed to replace this bolt I would try to obtain a 10.9 grade if using the metric convention.

I worked for 6 months prior to university in the quality control lab at Automotive Products. Back then every thing was still imperial so the high tensile bolts were all graded R, the weakest, to V the strongest. R was 45-50 tons/sq inch tensile, but I have not calculated that out in kg/sq mm. Whilst checking on R grade bolts, it listed 10.9 grade as the intermediate between 8.8 and 12.9

Is 10.2 the correct designation for the bolts? I read that 8.8 referred to a tensile strength of 80 kg/sq.mm ( I think the units are correct) and a yield point of 80% of tensile. Similarly 12.9 refers to 120 kg and 90% yield. If this is correct then 10.2 would indicate a very stretchy bolt. To quote a previous post rather like liquorice.

If you run the engine with the cap on, the top of the radiator will remain cool then suddenly get hot when the engine is up to temperature and thermostat opens. That is what I have observed with my cooling system. If the temperature of the top of the radiator gradually gets warmer, that would indicate that the thermostat is stuck open.

My handbook states 18.5 mph/100 revs in non overdrive 4th gear with 155/80/13 tyres. Checked with a GPS speed indicator which confirmed that my speedo reads 10% low. I found that the 175 tyres on 4.5J rims were too wide leading to excessive side wall flexing and handing improved on reverting back to 155 section tyres.

I fitted a similar electronic ignition system supplied by RetroRockets to my 1500 Spitfire built in 1975 but with a 1976 registration. This was about 10 years ago. I seem to remember something in the instructions that some Lucas distributors were manufactured with a different lobe height and these were unsuitable for their system. On measuring, I found I had one of these "unsuitable" distributors; yours is a similar age so perhaps the same applies to your distributor? I worked around the problem by finding a rubber O-ring that fitted within the actuator and acted as a spacer so that the magnets aligned with the pick up as in your second photo. This prevented the actuator sliding down to the lower position shown in the first photo. The system has worked faultlessly since the initial fitting. I have checked the timing several times over the years but it has never changed.

I have never stripped the gearbox but this attachment might help. gearbox.pdf

I am always suspicious when people film something like this as they must be expecting something "amazing". How many times have you filmed a regular oil change and invited your mates to come and watch?

I found it very difficult to access the terminals with the switch in position which is why I said test with the switch out of the dashboard. If you can test with the switch it position, switch the ignition on and check for 12 V on terminal 3, the other probe of the multimeter being earthed through any unpainted metal such as the head of a screw. If there is 12 V on 3, move switch to the first position and check that for a reading of 12 V. Finally move switch to second position and check for 12 V on terminal 4. Do not use the buzzer on the continuity setting if testing a live circuit. Off to cook my evening meal but may be back later.

While you have the switch out, you should also check the continuity between 1 and 2 with the switch in the Off position as this controls the self parking mode.

As you appear to own a multimeter, you can use the buzzer on the continuity check setting to test 2 to 3 (or 3 to 2, it makes no difference) and then 3 to 4 as you operate the switch. I have found that some times you have to scratch the connector with the multimeter probe to get a good contact. Alternatively you could attach a known 12 V supply to contact 3 and check for 12 V on 2 in the first switch position and 4 in the second position.

I think Pete is referring to a different type of switch to the one that rotates as fitted to early Spitfire 1500. As the switch also incorporates the washer pump (?) I cannot see how it can be easily dismantled. They are not cheap so I would remove the switch and check for a connection between 2 and 3 in the first position and 3 and 4 in the second position. If this proves satisfactory, then it is a wiring fault otherwise a new switch is required. It might help to repeatedly operate the switch to try to remove oxidation from the internal contacts before testing the switch.

Reminds me of cycling with a colleague who claimed he had saved 2 oz by filing down the gear change mechanism. Looking at him I guessed that he was 2 stone overweight.

When the dashboard switch is off. you should have 12 V between the black (earth) and green. When switched to slow there should also be 12 V on the Red/Light Green When switched to fast there should be 12 V on the Blue/Light Green The Brown/Light Green is the return to the switch from the parking mechanism. This assumes that you have the later twin speed wipers as fitted to the 1500 Spitfire. The problem with the wiring diagram posted previously is that it is for the USA export models and there are several differences compared with UK models. However, the coloured diagram is easier to understand than the black and white version in the workshop manual, just do not start looking for your bulb check relay and several other components! The following diagram may help:

I worked at Automotive Products in Leamington for 6 months prior to university. Borg and Beck was part of Automotive Products. That was many years ago; the way trade names have been sold on, for example Rolls Royce and Bentley, who knows who the current owners are and whether they are still the same company.

My understanding is that the colours were originally designated by a 2 digit code, all the reds ended in "2", all the blues ended in "6" etc. The system then changed to a three letter code, CAB is just the later code for Pimento Red.

After I had replaced the clutch slave cylinder on my Spitfire, I opened the bleed screw (must be at the top of the cylinder) and the fluid just flowed out as the reservoir is the highest point on a straight through hydraulic circuit. Closed the screw after a few seconds and the clutch pedal worked perfectly. No need for a second person to pump the pedal. Or was I just lucky?

Interesting that the MGF has a whole manual for the electrics, my Spitfire wiring diagram is one page in the owner's handbook !