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Re: 77 with Dual SUs

To: "doug russell" <dr-doug@classic.msn.com>,
Subject: Re: 77 with Dual SUs
From: "Paul Hunt" <paul.hunt1@virgin.net>
Date: Thu, 11 Mar 1999 20:19:32 -0000
Speaking generally, once you have set the jets to their starting position
you should balance the air flow using the idle idle screws before moving on
to adjust the mixtures individually using the jets.  After adjusting each
jet you should recheck the other carb as they are interdependant.  I have
just loaded up the full monty on setting up twin SUs (as well as
distributors, front hubs and other stuff) on the 'Hammer and Spanner' page
of my web site.

PaulH.
http://freespace.virgin.net/paul.hunt1/

-----Original Message-----
From: doug russell <dr-doug@classic.msn.com>
To: mg mailing list <mgs@autox.team.net>; DOUGLAS_RUSSELL@yr.com
<DOUGLAS_RUSSELL@yr.com>
Date: 11 March 1999 01:10
Subject: 77 with Dual SUs


>List,
>
>Long time since I've posted but I need some help diagnosing a problem I am
>having with a new Dual HS4 SU conversion I made on my 77B.
>
>First, thanks to David D. for the parts.  He was generous with his time and
>engenders everything that is right with our hobby/sport.
>
>The conversion went along just fine.  I had a couple of roadblocks such as
a
>leaking needle connection and some other stuff that were pretty easy to
>overcome.  I still have the following two issues.
>
>1. The carbs backfire like crazy.  Here's the story.  After setting the
needle
>height to be even with the bridge in the carbs I backed them down 12 flats.
>Then conducted an air flow test where I lifted the pistons (at the same
time)
>ever so slightly (about 1/8") and got a slight rise in RPMs, indicating a
rich
>mixture, so I went up by one flat until the idle did not change when slight
>lift was applied.  So far, everything is by the book but I can't get the
carbs
>to stop backfiring.  When cold, they backfire like crazy but quiet down
>substantially when the engine is warmed up - but still backfires especially
>when accelerating slowly (a heavy foot almost eliminates the backfiring).
>Also, when the choke is applied, the backfiring stops.  Sounds like it's
>running too lean right?  So I make the mixture richer and still get
>backfiring.  Anyway, I trust this is something easy that I'm overlooking
for
>which you all can suggest a remedy.
>
>2. I have an exhaust leak at the head-exhaust manifold connection for #2 /
#3.
> I have used a single gasket that burned right through after 10 minutes and
>over the weekend put on a double gasket but it also burned right through.
Any
>ideas on how to get rid of the exhaust leak?  Is it possible that the
exhaust
>manifold needs to be milled straight?  If so, who does this work?  Are
there
>torque specs?
>
>Other that this, life is great and I'm looking forward to another season of
>shows and seeing some of your butt ugly mugs over the summer (Speaking of
>which: Macy, don't you still owe us all some beers or something???).
>
>Dr. Doug
>
>BTW, an elderly gent in my area is looking to get rid of a 58 or 59 Jag
150s
>that has been sitting in his garage since 1972.  Also has a tranny with OD
for
>an AH 3000.  If you are interested drop me a note.
>
>BTW BTW - I'm on the digest so please CC your reply to the list to me at
>dr-doug@msn.com - thanks
>


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