Sunday, 6 July 2014

Towards the MoT

26 April
The brake master cylinders have now been ‘bench bled’ (though without removing them), and the feel is much better. I’ve dispensed with the three individual fluid reservoirs. They were prone to leakage and made access to the master cylinders difficult. I now have a single reservoir bolted to the back of the wheelarch.

The carburettor’s been stripped and cleaned, air passages and jets blown through, though with no obvious fault spotted. I measured jet sizes and replaced one of the primary jets with one from my tuning kit which better matched the size of the other. I’ve also measured all plug lead resistances and re-checked coil resistances, etc. and found no fault. I’ll have another go at running the motor next week and see if I can narrow anything down.
01 May
Made some passenger seat supports from aluminium channel, and also cut some for the MX5 seats. I’ve been trying to find a way of not drilling additional holes in the floor for the MX5 seats, but think this is going to defeat me.

Gerry’s header tank and support bracket delivered. The bracket mounts it a couple of inches too low – it needs to be the highest point in the system. A couple of plates can be made out of aluminium to raise it up to the level where the previous tank was mounted. Other than that, the Rover top hose can be cut in two to fit both into and out of the header tank. The fan thermoswitch, I now realise, screws into the boss at the top of the radiator. All in all, the cooling system is simplified with fewer joints.

I’ve fitted a valve in the fuel tank vent, one that operates both ways at a small pressure. This should help to stop the fuel smell, but was a bit expensive.

At last a communication from Speedy Cables to say the speedometer should be ready by the end of next week. They really haven’t lived up to their name, this was sent to them on 21st February!

04 May
The engine’s been running again (after replacing a blown diode bridge). No sign of the previous misfire, but still a lot of top-end clatter to be investigated. Cooling system almost completely continent! The dwell’s checked OK at around 35 degrees.

Checked the wipers with the engine running – unfortunately the fast speed isn’t sufficiently faster than the slow speed to comply with IVA requirements, so I’ve ordered a new motor. I’ve also ordered some switch identification stickers.

Spent some time making seat brackets to adapt the MX-5 seats. The seats sit very low and are compliant with IVA requirements for seat belt height with a good margin – nearly 2 inches!

More time spent bleeding the brakes. Hopefully getting a bit less spongy.
13 May
Fitted the new wiper motor, notable increase in speeds, though not yet checked frequency. Speedometer received back, calibrated, and fitted. Spent a bit of time tidying under the bonnet, and some time on seat frames and locations to aid transfer of the MX-5 seats.

The fuel pressure gauge doesn’t work properly despite now being correctly wired. It really needs some advanced diagnostics, though currently I’m suspecting the sender unit. It seems to give an output voltage of around 200mV when the fuel pump’s on, which sounds much too low.

I’ve been filling in forms and collating paperwork in preparation for sending off with the IVA application. Probably do this when I’m back from holiday in a couple of weeks. There’s really not too much left to do on the car.
10 June
Big step forward is I submitted the IVA test application a week ago. This coming Saturday I’m trailering the car to my MoT garage for a sort of pre-MoT and to help me balance the brakes. Worked out I needed to trailer the car around six times (maybe more) so in the absence of a very local hirer I’ve bought secondhand a neat Brian James four-wheel trailer which fits in the garage.

I’ve spent a bit of time ‘snagging’ and getting things in order for the test, ensuring all wiring’s covered in convoluted conduit, bolts are sticking through nuts properly, and pipes and wiring are well supported. I’ve also obtained a new timing light and gastester to replace my 30-year-old ones which didn’t work any more!  I’ve adjusted the timing to 10 degrees BTDC static, vacuum advance disconnected. I think this is a reasonable starting point. I’ve adjusted the carburettor to give CO levels of around 3% which is well within the allowable for the age of engine.

I’ve started to cut out footwell carpets from a roll I got cheap at a local autojumble. Although patterns are now made for my own, I’m not confident of them being finished before IVA test time.

Still some niggles – the engine rattle being the largest, sounds tappety but I’ll get a view from Andy at Grappenhall Motors on Saturday. Not yet fixed the fuel pressure gauge, though I’m suspecting a faulty sender unit, and the float on my fuel gauge sender has sunk! I’ve sent for a brass replacement from Moss.
05 July
The ’pre MoT’ was a proper MoT – which I failed on brakes, rear brake and handbrake efficiency too low. The trip also revealed some persistent clutch drag which caused dome difficulty engaging first and reverse. A second visit with tightened handbrake didn’t turn out much better. I puzzled over it for a while – then realised I’d been misled into believing I needed a strong bias towards the front brakes. The set up I’ve got is MGB – the original MGB had single-line hydraulics, with no pressure limiting valve, so the balance bar setup should be 50:50 front to rear. However, my Hawk has a little more rearward weight bias, and has high friction (Greenstuff) front pads –so I need a little bias to the rear – not too much, which would upset the IVA.
I’ve gone back to first principles to calculate the setup – I may send this to Phil to see if he thinks it’s worth publishing.

I swapped the 0.7” master cylinder on the rear brake line with the 0.625” clutch master cylinder, and adjusted the balance bar to give approximately 53% bias to the rear brakes. This solved both problems – the clutch operating lever has more stroke and now allows quiet and easy engagement of all gears, and the brakes passed the MoT today!

Rear drums have been drilled with inspection holes in case the IVA people are applying the letter of the regulations.

The MoT emissions test showed that somehow my CO emissions were less than 1%. So much for the Gastester. I increased them to a healthier 3%!

I’ve spent some time with carpets to make the interior look a bit presentable while I wait for Gerry’s carpet set to be produced, though there’s a bit more to do. I’ve sorted the fuel gauge with a new float. I’ve tidied up a number of loose ends in advance of the IVA test – which is booked for 8:00 on 23 July.

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