Wednesday, September 27, 2006

An interesting day

I went up to Canley’s yesterday to help Dave get the venue ready for the driver’s briefing and to get him to lay hands upon the Vitesse. I reciprocated by laying hands on his Stag, dredging up my knowledge of SU fuel pumps from 25 years ago (my first car was a Morris Minor) and being entrusted with rebuilding the distributor internals - first time I'd ever seen dual points, interesting!

The Vitesse had been pretty good on the way up, the fuel pump behaved and felt cool when I tested it. I ran in daylight with the lights on dip to ensure nothing got too hot in my new wiring – an hour+ running like that was fine. The fuse holder was warm but not excessively hot – I didn’t burn my fingers again! I bought a new one anyway to be sure.

There is an annoying vibration over 70 mph, it’s one I can feel through my backside, the steering wheel is fine. It feels like driveline – the prop is new so could it be rear wheel balance? These tyres haven’t been on a year and were fully balanced when fitted – I’m not 100% sure they were well balanced as they seem to have a LOT of weights on. I might take them down to my local tyre place and see if they can improve them.

I though the engine had been running rough, maybe a slight misfire? I sometimes think I get paranoid about these things! I’ve been playing with the timing and wasn’t very happy with it, it wouldn’t idle properly and was reluctant to start. It smelt very rich, the plugs were fouled (I must pull them again after yesterday's 200 miles). I tinkered on the way up and got it to feel better – it steadfastly refuses to pink and pulls OK through the rev range. It’s now running something like 14 degrees of advance and as Dave says, it really shouldn’t need more.

Some fiddling with the metering unit hasn’t improved the rich running but Dave was able to get the mixture leaner by inserting a feeler gauge between the shuttle and the control plunger roller – you can adjust this to compensate for wear but mine is adjusted to the max. This may help explain from the very useul pages of

There are several ways to adjust the metering unit, it is something of a black art and does seem very complicated. However, as I understand it, what needs to happen is the shuttle travel needs to be reduced. This can be done y either adjusting the control plunger roller to be closer to the shuttle OR, as in my case when you’ve exhausted that range of movement, you can add material to the shuttle. The tolerances inhere are really fine so Dave recommends running the car at idle, selecting the right gap by inserting a feeler gauge to lean off the mixture – you can hear the engine note change and go past the optimum. Once you’ve selected the right feeler gauge (Dave thinks about 4 thou should do it) then cut the end off the feeler gauge and stick it onto the shuttle. Araldite should be OK, I could swear I've seen this method written up in an article - solder was used to stick the feeler gauge on the shuttle - I can't remember where that was though!

The Metering Unit will have to come off the car to do this (the sticking bit, the rest has to be done whilst it’s running) but that suits me as I can then renew the two banjo bolts (injectors 5 & 6) that are impossible to get to with the MU on the car.

I should be able to do this in the next couple of days but we’re getting close now!

I never did get the car on the ramp to look at the exhaust, however I did test my ear plugs on the way back :-)

Another annoyance is the fuel gauge, I thought I'd fixed it but now it’s always reading full! How the hell do I trace this fault? Apart from the obvious visual inspection for crap connections? Any ideas??

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