[Healeys] Missfire/"Puffing" Continuing

Warthodson at aol.com Warthodson at aol.com
Mon Aug 4 07:40:56 MDT 2008


Phil,
I would agree with the replies that say you have it tuned, but, it you want  
to experiment a little more, here is what the SU says:
 
The effect of mixture strength on exhaust:
TOO WEAK: Irregular note, splashy misfire & colourless
CORRECT: regular even note
TOO RICH: regular or rhythmical misfire, blackish
 
I would suggest that you check the mixture by performing the test  in the 
shop manual that involves carefully pushing up the "lifting Pin" on the  carb. 
The manual describes the process. I assume you have already syncronized  the 
carbs.  
 
You could also try leaning the carbs, then try richening them, to see  if 
there is any change. Keep detailed notes so you can return it to the  original 
setting. 
 
Finally, How did you set the 15 degrees timing? was it static, or at idle  
(what RPM)? Was the vacuum advance line connected to the distributor? If you  
know someone with a "dial back to zero timing light" (or you have one) it might  
be of interest to know what the timing is at Max. advance. Disconnect  the 
vacuum advance line, warm up the engine & run it up to approx.  3000-3500 RPM. 
With the timing light, check the advance by dialing the timing  mark back to 
zero & reading the degrees of advance on the timing  light.
 
Or you could leave well enough along!
Gary Hodson  
 
 
 
In a message dated 8/3/2008 4:32:48 P.M. Central Daylight Time,  
PhilRitten at aol.com writes:

All,

I am still getting a "puffing" noise from my BN4/6 after I  have driven  it a 
little. After warming it up, I take it up on the  freeway a mile or  two, 
turn 
around and bring it home. After that,  every fourth  or fifth sound out of 
the 
tail pipe is a "puffing"  sound. Interestingly, the  idle is still smooth (no 
obvious missing).  The only way you can tell there is a  problem is listening 
to 
the  tail pipe.  BTW - when idling and warming up in  the garage there is  a 
steady staccato sound from the tail pipe. 

I'm rather puzzled. I  replaced the plugs/cap/rotor/wires and set the  timing 
around 15  BTDC. I looked under the hood at night (in the dark) to see if  
there  was any shorting and didn't see anything. There doesn't seem to be the 
  same 
problem with the rotor rubbing on the cap that I had before. By the  way, I  
have electronic ignition.

I'm wondering if it could be  something like a bad coil or something that  
fails once it has warmed  up.

Thank you all,

Phil



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**************Looking for a car that's sporty, fun and fits in your budget? 
Read reviews on AOL Autos.      
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