We are about to do a couple of long trips in the Jaguar, one to the Hunter Valley (245 km / 150 mi) and to Parkes (260 km / 160 mi) so I though it a good time to check the tuning to see what's amiss. Was it running rich? What was the ignition system like?
I started by removing the spark plugs. They were quite sooty for what appear to be fairly new plugs - so I gave them a clean up, re-gapped them as they appear to have not been set to the required 0.022" from new, and re-installed them.
I then checked the points gap, they appeared to be on the required 0.012". They are in a crappy spot to work on, I've been spoilt in the past, Morris Minor distributors are in a very convenient location, even more so on the lovely side valve engine. The Rolls-Royce was typically easy V8 affair.
Then I proceeded to check the ignition timing. It was perfectly set to 5°, unfortunately it had been set to after TDC, not before! And the last tune was performed by a "qualified" mechanic! Lucky us mere amateurs are on the case. As soon as I started advancing the timing, the engine ran quieter and idled smother. I think the strange exhaust sound I was hearing was actually late combustion occurring in the exhaust port. I set the timing to around 7° BTDC and took the old girl for a 20 km drive. She seems to pull better and has more low end torque.
I checked the mixture of the front carburettor, if anything it was a little lean - not rich. I will leave adjusting the carburettors for another time.
I will be interested in checking the petrol consumption now I have fixed the ignition timing.
Coming next....... well erect trafficators! :-o
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