Doug..........
If your manifold is warped so badly that you burn through the gasket in that
short a time, there's an excellent possibility that it is also leaking
around the intake flange - thus seriously leaning out your mixture.
Definitely have the manifold surfaced. No terribly clever machinery is
needed - just a belt sander that can accomodate the full length of the
manifold. Be sure to clean it out REALLY thoroughly afterwards, though.
Lawrie
British Sportscar Center
-----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: Wednesday, March 10, 1999 5:10 PM
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
>
|