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Re: Lean at cruise

Subject: Re: Lean at cruise
Date: Mon, 8 Mar 1999 23:23:57 EST
In a message dated 3/8/99 10:28:52 PM Eastern Standard Time, writes:

<< Hello everyone,
      New to the list but have owned my 1974 B since 1994 and spent three
 years in restoration. Any info appreciated on a problem that shows up at
 cruising speed ( between about 50 and 60) The engine seems to miss on light
 throttle going up hills. Under hard acceleration no problem, but to just
 hold constant speed ascending a grade with gentle increase in throttle the
 engine misses. One day just as a test I pulled the choke out to richen up
 the mixture and the miss dissapeared. OK, so this suggests engine is running
      I checked vacuum advance, timing, and HIF carbs. Smog pump and
 associated technicalities were all removed by previous owner. I looked and
 poppet valves in the butterflies are soldered shut. Idle is a little lumpy,
 and seems hard to get idle mixture from running too rich ( according to
 colortune) Ignition seems to be hot enough ( according to the oscilloscope).
      The final culprit is the carbs. The car has 68,000 mi and engine was
 rebuilt 2,000 mi ago, but carbs were not. I have tried the old spray em with
 something and see if the idle changes but can't seem to find the problem.
 Idle is too rich and cruise is too lean. So if the problem is the carbs,
 several questions come along  A. to replace or rebuild. Is new better? Is
 rebuild or just new needles only delaying the inevitable?  B. SU or Weber? I
 guess I really don't mind tinkering with the stock dual carbs. It's kind of
 a badge of honor to keep them happy  C. HIF 4s or HS4s?   I have a set of
 used HS4's on the shelf that could be rebuilt. Do HIFs have
 problems/drawbacks in being designed for emissions compliance rather than
 engine performance? Might even buy new HS4s?
      I'm going to need to decide, my wife actually asked me what I wanted
 for my birthday coming up soon, and someday the Iowa snow will melt and I'm
 going to want to drive.
      All two cent suggestions considered at current market value.
 Thanks everyone, >>
You are probably right with carbs being the problem but also check spark plug
gap. Wide gap at high 60mph with "normal" coil will cause hesitation.

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