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Running slightly lean & no more adjustment?

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PAUL161

PAUL161

Great Pumpkin
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The HIF-4s apear to be running slightly lean and there is no more adjustment on the jets. The tail pipe looks good as it's a brownish tan. The plugs look like there running a little hot, white tips. There are no vac leaks anywhere. I would like to enrichen the mixture just a tad. I can't remember the needle sizes, but there the stock needles. The engine runs great but idles a little rough. The timing is on the money. Any clues? /ubbthreads/images/graemlins/confused.gif PJ
 
I would say it's time for a carb rebuild...I had the same trouble with the white MGA....After about a year of continuous fiddlin with the mixture I rebuilt them and it's been great ever since...
 
Lean has to be either too much air or not enough fuel so if you're REALLY SURE there isn't a vacuum leak then there must be varnish or gunk or something occluding the jet and restricting flow. So yeah, a carb rebuild is in order.
 
Don't get to use the word occluding much do we? Ah, I used it. I feel better now. /ubbthreads/images/graemlins/jester.gif
 
Timing was off! Too far advanced. Dizzy shaft was loose. Replaced dizzy with one with new bushings. Retimed and now plugs are the right color, the idle is better and throttle response is great! /ubbthreads/images/graemlins/thumbsup.gif /ubbthreads/images/graemlins/thumbsup.gif PJ
 
Outstanding, must be about time for everyone to check Dizzy shaft bearing. All together now, check shaft bearing. This is about the fourth problem like this in a month.
 
Goes back to the "most carb problems are in the ignition system" theory. Had mine in my hand yesterday. 25D, all good.
 
The only thing I can figure Doc, is that the shaft is so short, even the slightest play in the bushing is exagerated more so than a dizzy with a long shaft. I'll never put one in again with a loose shaft! /ubbthreads/images/graemlins/nonod.gif /ubbthreads/images/graemlins/nonono.gif PJ
 
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