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Spluttering Midget.

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Baz

Baz

Yoda
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The symptoms.....
Thursday night, myself and another guy were trying to nail down the spluttering at 4500 rpm. Adjusted timing, no different, vacuum OK.
We drove it richer and much better, all the way to full rich. Drove it then with the choke 1/4 out and that's where it wanted to be, all the way to 7000, no problems, sounds great and had uumph.
As the car gets driven and warms up, the mixture goes all over place.
Plugs were clean thursday, black, sooty and nasty now. Clearly too rich.
So why is it going from one to the other? Needles maybe?

Drove it this morning, and was nice and happy at first, then goes to mush after about 1/2 hour of regular driving. Very hot under there too.
 
How about an air leak?
 
Sigh..........

How about a condencer going away or a coil doing the same.


Naah, has to be carboration. Fuel delivery?
 
I think I used a can of carb cleaner looking for a leak. Dizzy components are new, rotor, points etc.
I've got a feeling it's not so much fuel delivery, but air delivery.....
It dawned on me ealier, the problems have been around since I put this air filter housing on, thoughts? Could it be in some way restricting my air flow? With it off, I can tune the carbs as normal.
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just thinking...(granted...just a little) but i look at that and think that the total area of that vs. a pair of completely round ones has to be less...........

mark
 
Oh really, it is ok with the filter off??
 
Much better Jack, three flats back to lean and she's happy. I think Mark is right about the area of the filter, it's just not sucking enough air.
I drove for 40 minutes with it off and the temp in the engine bay was a little cooler too.
(I forgot to let my tires down too) /bcforum/images/%%GRAEMLIN_URL%%/nonono.gif
 
That's too bad, that is a good looking filter.

Anyway is good that you found the answer, many seconds were lost on that run with the engine misbehaving.

Luck on your next outing.
 
Thanks Jack, one problem sorted, another one appears.
Found a puddle of brake fluid in the footwell, looks like a master rebuild is in my future!
I wore the poor girl out!
 
Haha, she is loveing it and is just telling you she needs a bit of help to do her best.
 
That thing looks real pretty, but you have to have as near to unrestricted airflow as possible to get the right performance.
Wouldn't it be easy to find a pair of round or even cone shaped K&N's? I believe I've seen those on Ebay, and elsewhere.
 
Have used that type air cleaner for years with no problems. Make sure you have the correct gaskets between it and the carbs. K&N element on this one.
 
That was my thought as well, what about the elememts. Are they clear?

Try it without the elements installed.
 
Yup, I too have a hard time believing that a filter with that amount of surface area can't suck enough air. I'd be more suspicious of a dirty filter, or the wrong grade of oil used on it?

But I don't think it can be the root of your problems. If, when enriched, the motor could get enough air to rev happily up to 7000, that seems to me to tell you that it's not simply a physical CFM filter design limitation.

I know absolutely nothing about tuning SUs, so I'll leave that to others for comment. Heat, loss of power etc. suggest that a timing issue is also possible, although I think you mentioned that you checked it.
 
I have that filter on both my cars and it breaths fine. If you compare the trumpet opening of the stock cans to this filter there is no question that it has enough area. Be sure the rear plate it installed with the correct side up and that the filter is clean. They sell a nice cleaning and lube kit for the element. Have you check the condition of the advance mechanism in the distributor? Mine acted funny when the linkage spring between the vacuum diaphragm and the breaker plate broke.
 
Oh my god, if the rear plate is upside down ie top to bottom it will cover the breathing hole, don't know what else to call it. Screws the carbs all up.
 
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