One possibility could be defective fuel. Many people in our club have been “slimmed” by micro organisms that grow in gasoline resulting in a clogged fuel delivery system.
Check your glass fuel bowl to check for evidence of these nasty creatures.
Bob
The frustration surely is aggravating, unwanted in a hobby activity. Maybe posting measured distributor mechanical advance curves versus rpm and vacuum advance versus depression separately, will help let people offer better advice. Note that vacuum advance at moderate rpm under load will not be the same as under no load or at highway rpms.
Also suggest measuring air/fuel ratio in the conditions of stumble.
Symptoms sound like too lean or advance way off under load at moderate rpm. Quantitative evidence in the “stumble” condition could help.
Best wishes on next steps and listers will look forward to hearing resolution for you.
beautiful motor car.
Timing can be checked static of course, and in the shop with no load, But do you know you have it under load with low manifold pressure?
Not sure how I could check that Karl.
Thanks Phil, it used to run beautifully as well.
And I don’t have a handy answer! I am assuming you have a vacuum advance distributor. You could retard your setting 20 degrees, take a quick drive around the block, and see if it improves anything. It would at least eliminate one possibility.
Yes Karl, I see. I planned on doing radical settings on both carbs and distributor once I can get the car out of shop. New driveway concrete has shut down playing on the road. Long time looking for Eureka!!!.
It will happen, one of the things I love about these cars, is they are too simple to get too far into the woods.
Just make sure its one thing at a time.
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it will again. just need to systematically go through the basics
With best regards
Philip Dobson
Have you swapped out the spark plugs?
Yes Paul, thanks. Changed out plugs twice if memory serves. I should have kept a log. At 72 memory can play tricks.
Finally solved 120 missing problem. I had installed a master switch behind drivers seat and ran welding type cables from battery in compartment behind passenger seat. Was fine for a while but cables had slackened enough that when accelerating , the body would drop enough for the cables to rub on the prop shaft shorting out the battery. I noticed the low fuel light would flicker off and on in time to the missing of the engine. Don’t I feel the fool. Poor install for sure. Anyway she is running her old sweet self and was looking good beside a gorgeous C type replica of Bert van Riel’s from Edmonton Sports Car Centre. Thanks again for all the suggestions and encouragement.
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now there is an issue not checked in a tune/miss problem…wow. I had a battery clamp…that intermittently would fail to pass power…took quite a while to find that…would drive just fine…then miss badly, even quit…start just fine…then no start…no electric… Nick
Never ceases to amaze the endless variety of things that cause missing and other performance issues. Just heard from a friend who ,all summer, has been chasing a miss at 3500 - 4000 rpm on acceleration on his E Type. Been though everything twice - finally by fluke discovered the piston in one carb was sticking on the way up. That lead to an overly rich condition ( increased air speed over the bridge, with increased depression, more fuel ) and a miss.
Don’t understand why I like and admire these old beasts as much as I do. Just know that I do and likely always will.
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