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The question was what vacuum you read on the dist vacuum hose in idle, David…
This will clarify whether you have ported or manifold vacuum to the distributor. Which is important for the initial advance setting. If the initial advance is set to ported vacuum spec, but is fed manifold vacuum - the ign will be far too high…
Indeed, a common range of the dist vacuum reaction is around 10 degrees - but the characteristics of the two vacuum sources to pedal use is different…
I read full vacuum, as it is manifold-, not ported vacuum! I don’t have a federal model so it is supposed to be non-ported, even though it used to be ported, but just as the wiring it was all over the place. Adjusted it was properly. It ran fine before England. The vacuum source is not the problem, but blocking it would negate the part-throttle pinging by removing these 10° or whatever. But then idle would be too low to drive, and I wanted to get us home, not mess up the entire car.
And as I said it is about fine for normal driving. I might take a timing light to it eventually.
David
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The intent of the ‘European’ set-up, using manifold vacuum, David - is to maintain high advance at high vacuum. Under load, drop in vacuum backs off ignition, preventing knocking. Ie, pedal use is meant to reduce advance by ‘blocking’ distributor vacuum source…
This required low centrifugal advance, vacuum disconnected, in idle - typically some 4 - 6 degrees The US configuration, ported vacuum, typically uses 17 degrees centrifugal in idle - as there is no vacuum with the throttle closed…
I wonder if your distributor is suitable for manifold vacuum, ‘even though it used to be ported’ raises questions?
It was ported just as the wiring for the full throttle switch and the full load switch were connected together instead of to the switches. Just as the vacuum sources were a mess. Just as the wiring in the center console was connected by wrapping a quarter inch of wire together and a bit of tape around. Not to mention the radio. Just as the fuel return pipe was not clipped on at all, and dangling around without brackets. Just as a fuel return valve was drilled and the chips were in the system. I could go on, bottom line, the distributor is not only correct, but has since been swapped with another unit; that had not changed a thing, it ran the same way for a thousand miles.
As I said, I’ll get into the issue and then start a thread if needed. Not much I can do from far away.
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Certainly, David - it’s just that a properly set and working distributor should not cause knocking, except in very extreme situations. And eliminating knocking should be easy without compromising performance…
My thinking goes back to previous discussions about ‘advance’ and ‘retard’ distributors - which also related to ported versus manifold vacuum…
I haven’t run across a 123 distributor. Like it! I’ve got a Pertronics in my Series II and well all that I can say it’s better than the wee-wobble one that was in prior. It was so bad, it would cook a set of points in 10 miles and got to the point it was making contact with the dist cap contacts and breaking rotors. Seriously in bad shape.
I’m not happy with the adv curve of the Pertronics it doesn’t really work well with a carborated configuration. Maybe if it went into the Series III or recurved. Which probably has to do with Franks point about the XK6 curve.
That’s what I thought too. Curve shouldn’t be different. I was talking with a local, one that I respect, Jag and Brit car specialist, and he said something about the curves being different - maybe it was the fuel… I thought he said the EFI system respond quicker than a carb config. maybe it was the ethanol in the fuel. it was a while ago. Anyway, - not real pleased with the end result other than it works.
Hi Edward, I have just picked up this thread from the forum. Can you tell me where you found the information for setting up your advance curves as I have the same engine and year with a fast road cam installed and can’t work out what curves to use.
I too am using a 123 tune