Friday, 18 April 2014

Almost working .....

14 Mar
Just about finished covering the steering wheel  - looks almost modern. Also been working to wire ammeter (needs testing), and new foglight switch to comply with latest IVA. Sourced some new washer jets with adjustable nozzles – the previous ones with fixed nozzles aimed too low. Spent some time on hydraulics, bleeding brakes and clutch.
Found the front overrider support brackets don’t line up with where I think the overriders should be and will have to have some drop plates fitted to lower the level by a couple of inches. There are a lot of fiddly activities at the moment, lots of time spent achieving not much!
I need to check the tappet clearances – the rough running of the left bank was I suspect due to low compression on one or more cylinders due to the valves not closing. One of the heads had more valve seat work than the other, which may have to be compensated by shims under the rocker pillars.
17 Mar
Steering wheel’s finished and in place, but the padded boss looks a bit naff and rather spoils the effect. I wonder if I can do something a bit better?
The foglight switch and control is fitted and working.
I’ve also removed the carburettor and inlet manifold to check the follower preload. I can see that it’s too high on No.3 cylinder, which I already suspected of poor compression. I’ll do the checks slowly and carefully over the next few days.
31 Mar
Obtained an MGB steering wheel padded boss, which as luck would have it fits the steering wheel perfectly!

Four panels have been made in aluminium to fit under the dash, and covered with leathercloth. These can’t be finally fitted until last – when all the wiring’s fully sorted, the instruments are properly fixed and the speedometer’s back from calibration (‘Speedy’ cables are taking forever – 5 weeks so far and a further delay of 3-4 weeks).

Tried shimming the rocker shafts to correct follower preload, but not able to get all followers within tolerance. Shelled out for adjustable pushrods, which are now fitted and adjusted.  Unfortunately having adjusted the preload, I tried the engine again (Mon 31st March), and the symptoms are unchanged. Time for some serious diagnostics ….
Also tried while the engine was running, the clutch – I wasn’t very convinced by the feel and sure enough it doesn’t disengage properly. I think I’ll have to take the hydraulics apart, but first of all I might try to disengage it mechanically to check the amount of axial movement required.

The delay with the speedo and the issues with the misfire and clutch are delaying the time when I feel comfortable to book the IVA test.
05 April
Improved the rigidity of the fog lamp and reversing lamp by making a small bracket to hook under the lip of the rear valance, fixed to the back of the lamp and to the main attachment point. They feel nice and rigid now, not forever being spun round every time I brushed against them!

I’ve also made a VIN plate. It looks just about passable, and the text is large enough.

Some detailing – I’ve fitted a Tecalemit 2800 model grease gun in the appropriate place under the bonnet. I think it will be decorative – can’t beat my Wanner for any serious greasing!

I’m now waiting for a fine day when I can get the car in the drive and start to tackle the mechanical issues. I think the clutch will come first.
13 April
Main job over the last week has been to tackle the clutch. This involved removal of exhausts and propshaft, then separation of the bellhousing  from the engine and partial withdrawal of the gearbox. I had the front end jacked high enough to give access without complete removal of the gearbox. It was clear to see what the problem was, the release arm was fouling the side of the bellhousing, but what caused the misalignment wasn’t clear at first, but was probably some incorrect assembly where the release fork met the thrust bearing. The pivot pin was the correct one, 43mm outstand. Funny thing was, after very carefully reassembling everything – and this isn’t easy – and reconnecting the bellhousing, I got exactly the same symptoms, with only half a stroke of pedal travel. I removed the slave cylinder and pushed the pushrod in and out a few times, something seemed to fall into place and the pushrod didn’t go back quite as far. I reconnected the slave cylinder and hey presto, full clutch travel! As I had the propshaft off it was easy to check that the clutch was disengaging properly.

A tip for anyone fitting the release fork: assemble the fork and slipper pads to the release bearing before offering up the fork to the bellhousing. The assembly can be held together with cable ties, elastic bands or lockwire to be removed after installation. The pivot pin can be screwed into place after locating on the release fork, and tightened with a shortened or adapted spanner. Don’t forget to fit the pushrod before offering up the release fork to the bellhousing.

While the exhausts were off I took the opportunity to make some final adjustments and seal the joints with assembly paste, all except the manifold-to-downpipe joint, which I’ve left untightened at present ‘just in case’. I’m also improving the action of the handbrake, to get rid of some internal binding of the compression spring, and contemplating making some aluminium seat subframes that will adapt the MX5 seats to the existing floor drillings.
17 April
Glorious Good Friday, spent working in the sunshine!
Front over-riders: made up some aluminium drop plates to lower the over-rider supports, drilled the locations alongside the grill and trial fitted the overriders. They look just about right, but of course will have to come off again for the IVA test.

The handbrake actions been improved with some internal mods moving the compression spring. The action is now more reliable.

Bled the brakes again by pressurising each system, but although no bubbles at the wheels, I still must have air in the master cylinders as the feel and action is poor. These will have to be disconnected and bled individually like I did with the clutch.

For the first time the car’s moved under its own steam. Only to turn in the road and re-enter the drive though! The clutch seems to work OK but gear engagement was difficult. For now I’m putting this down to lack of oil circulation through the gearbox, rather than any mechanical defect, and hope that it gets better! I’d wired a test strobe in series with the plug for the suspect No.3 cylinder when I fired up the engine, which flashed away giving me no cause to suspect the spark. I removed the plugs and carried out a compression test, first on No.3, expecting to find a low reading. I got 140psi which I was reasonably happy with, though! Other cylinders varied between 150 and 165psi. Finally I repeated the test on No.3 and it gave 155psi. I think overall the range is reasonable and low compression isn’t a cause. I’ll probably check the carburettor next – I remember my old Scimitar regularly blocking a jet and running rough.

Another concern is there’s a knocking coming from the engine, not sure where, but now the exhaust joints have been quietened it seems louder. Further investigation due.

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