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Re: SU assistance needed

To: George Merryweather <merryweather@venus.connectware.com>,
Subject: Re: SU assistance needed
From: Paul Hunt <on76@dial.pipex.com>
Date: Fri, 07 Feb 97 19:16:15 GMT
> 
> OK folks, I am hoping that some wise sage on the list has had this
> problem before.  A quick fix would be nice, but just a fix at all would
> be great!
> 
> 948 MOWOG special
> twin SU HS's     The young man who brought it by complained that it was
> running rough.  He was right.  Barely running at all.  Carb linkage all
> screwed up, etc.  (Dad had tried to fix it)
> 
> Straighten out the linkage, replace the adaptor bushings on each one,
> put the carbs back on and fire it up.
> 
> It run real rough.  Actually both son and dad says that it sounds better
> but it is not anything I would take out on the road.
> 
> Uncouple the linkage, and put on the trusty Unisyn.  Rear carb appears
> fine.  When placing the Unisyn on the front carb, RPM picks up about
> 1500!  OK, so maybe it REAL lean?  Adjust the 'jet nut'.  The rear carb
> is at 7 flats, the front is now at 15!.  Unisyn has about the same
> effect.  Engine is still running, sort of.  Check linkage, jet seating,
> etc., while it is running, and no success.  Now the interesting
> part.....Both pistons are about 1/8" off the body at idle.  OK.  On
> acceleration, the rear slides open nicely, the front one CLOSES! Piston
> problem?  Shut it down, exchange pistons and housings front to rear,
> fire it up, problem stays to the front.
> 
> Check the spark plugs, #1 looks OK, but they get darker as you move
> back.  So it appears that its running off the rear carb.  That is
> further validated by the Unisysn problem.  Rear is running rich to carry
> all 4 cylinders, #1 is real lean.  Maybe a blockage in the jet?  the
> little tube from the bowl? etc.  But it could be running real lean if
> there was a vacuum problem.  As evidenced by the piston dropping on
> acceleration.  But why would the piston drop.  They are on the same
> manifold.
> 
> So have I given you enough info to come up with a miracle answer.  I
> hope so!  All suggestions welcome.  I fooled with this till about
> 11:00pm last night, with dubious sanity at the end.  (It was probably
> dubious to begin with!)  Before I give it another shot, I thought I go
> for some advice from the group!
> 
> And it still amazes me that the guys thought it was running better than
> before.  Before must have really been bad!
> 
> Your assistance is appreciated.
> 
> I won't be insulted is you suggest something dumb, simple, or stupid.  I
> do those three real well!
> 
> (I must be missing something real obvious!)
> 
> George Merryweather
> merryweather@connectware.com
> 
> 

I think I'm up to date with the digests but haven't seen a response to this 
yet.

Very small hole (instead of a big one, that is) in the front carb to manifold 
gasket?


PaulH
73 Roadster (HD&H)
75 V8 (DD)


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