Hello folks - I just bought my 1970 E-Type and there are a few issues I need to correct. I’ve ordered some books and such, but I did a little diagnosis in the meantime, and wanted to run a few things past you all for feedback.
Issue 1 - This car doesn’t suck …no really…no vacuum?
The primary issue I am investigating is a miss at idle - worse when cold, better warm, but never completely clears. I actually drove home with the choke out slightly to keep the revs a little higher - seems to take a very long time to get warm, though as I said, the miss never clears completely. I checked spark and all wires are receiving good, strong steady spark, so I moved onto vacuum and encountered and odd thing that may be normal for these cars, or maybe not, so I thought I’d check:
I tested vacuum coming from the front stromberg carburetor, the line that typically goes to the vacuum can on the distributor (vacuum retard on these cars, if I recall) . I only got 2 - 3 HG vacuum however - seemed really low to me. What should the vacuum reading be off the carburetor? and is it ported or manifold vacuum? As this is emissions, I suspect ported.
There is a metal line that starts at each carburetor, runs along the passenger cam cover and connects to the head at the front - (Crankcase ventilation / precursor to PCV valve I suspect). This line then continues out of the “cap” on the other side, follows the driver’s side cam cover and eventually connects to a canister behind the battery, adjacent to the brake vacuum booster. This line had no vacuum at all. The line is broken before it gets to the canister beside the brake booster, and has no vacuum signal at all. I expected there to be a vacuum signal from the carburetors, to draw / ventilate the crankcase and draw the fumes back into the carb to get “reprocessed” - but nothing.
The brakes work very well however, so the car is making vacuum, but I’m not sure what to make of the lack of vacuum from the carburetors.
Issue 2 - The hypnotic pulsing lights
This, I think, is a alternator problem. The symptoms are these:
a) With the lights on, and any lights - dash light, map light, headlight, running lights - all of them, the lights pulse - brighter and dimmer, and do so in time with a noise seeming to come from the alternator. Increased RPM does not make the problem go away - they may occur faster, but still present. In addition, the more electrical load you add, the slower the pulses. So, for example, if I have just the map light on, and watch it get brighter and dimmer, I can flip on the headlights and the pulse will slow.
b) The alternator seems to make noise - either that or its something in the direct vicinity, such as a tension pulley. The nose is in time with the “light pulses” and I noted a deviation the alternator drive belt at the same time - it seems to be looser for a a fraction of a second.
My thought is that perhaps the alternator is increasing and decreasing output every other second - thus creating and releasing drag - so that would explain the belt and the pulsing lights. Similarly the noise might be when the alternator is under greater load. My second thought was a bearing in the alternator might be on its way out, and so its causing a noise and uneven drag. I also thought perhaps the voltage regulator could be at fault, but with a quick look I wasn’t able to locate it - I’ll look again tomorrow.
Would appreciate thoughts on these from you experienced owners. I have some familiarity with the MK2 and quite a bit working with U.S. engines, but the 4.2 emissions-laden XK is new territory for me.