Thanks, The HIFs will go back on after I rebuild them over the next few
weeks. I need to get the car running good enough to drive in the meantime.
I'll try the timing adjustment but don't think it will work as there's no
difference in the way the car runs with the vacuum advance disconnected,
connected to the throttle orrifice tap, or connected to the manifold. But
hey, I was wrong once before ;^)
Dennis Vaders
"There can be no great ingenuity
without
an admixture
of dementedness"... Seneca or somebody
-----Original Message-----
From: Max Heim <mvheim@studiolimage.com>
To: MG Mail List <mgs@autox.team.net>
Date: Friday, July 16, 1999 1:43 PM
Subject: Re: B Backfire w/ Weber DGV
>Well, my opinion would be, rebuild the HIFs and put them back on.
>Different is not necessarily better. "Weber" is just a brand of
>carburetor, not a magic performance cure-all.
>
>...but, having said that (which you're free to ignore), you might want to
>try more advance, up to 15 degrees or so, and see if that improves things.
>
>Good luck!
>
>
>Dennis Vaders had this to say:
>
>>Hi All,
>>
>>Just joined the list and wanted to jump in with both feet. FYI, my first
>>car was a 59 bugeye sprite and while in high school I had a vast
collection
>>of midgets. As I'm still experiencing my first childhood (forget about
the
>>second!) I've gotten back into the MG "business" with the purchase of a
>>'73GT basket case and a '73 roadster. I just got done installing a new
>>clutch in the roadster and while I was at it I replaced the main and rod
>>bearings and timing chain. I also installed an almost new DGV from the GT
>>(GT had blown an engine before I got it).
>>
>>The car ran almost fine before I removed the HIFs (bad idle, etc)
>>but now I get some backfire through the weber carb and no power. I'm 99%
>>sure the
>>timing gears were lined up properly when I put the chain on. Here's some
>>more data:
>>
>>Car idles fine
>>Backfires through carb regardless of if and where vacuum advance is
>>connected.
>>Timing is at about 7 degrees at idle w/ distributor disconnected
>>Backfires under power at larger throttle openings
>>Car will continue to run even when mixture screw is fully closed
>>At idle fuel drips from the small feed tube in the small venturi of the
>>primary throttle bore (not the accelerator tube)
>>Donor car ran fine with the weber (until the engine blew up)
>>Weber was cleaned out prior to installation but didn't need much clean up
as
>>it was almost new when put on doner car and wasn't on long before the
engine
>>went out.
>>
>>I also copied the following off of some other web site:
>>
>>"WEBER 32/36 DGV (all MGB's 1963-1980)
>>While a very reliable carb/manifold set up, a disadvantage with this
>>carburetor is the fact that the primary venturi accounts for two thirds of
>>the throttle open position (no CFM* figures are given for this position)
>>with the secondary venturi becoming active in the final one third of
>>throttle movement. This carburetor requires excessive initial ignition
>>timing advance to avoid stumble on take off (if the ignition timing was
>>retarded, we would have to open the primary throttle plate to obtain the
>>necessary idle; this would expose the progression bleed holes which in
turn
>>would require that the idle mixture be leaned to compensate for this
richer
>>mixture condition. The end result being very little progressive richening
>>upon further throttle opening, especially at snap throttle and so the
>>stumble). Carburetor can be modified to allow the primary & secondary
>>throttle plates to open simultaneously plus modifications to the
progression
>>circuit and accelerator pump at a reasonable cost. Unfortunately, the
>>company that had provided this service no longer does so."
>>
>>
>>
>>Any suggestions would be greatly appreciated!
>>
>>Thanks,
>>
>>Dennis Vaders
>>Elkin, NC
>>
>>
>>
>
>
>--
>
>Max Heim
>'66 MGB GHN3L76149
>Runs great,
>looks particularly bad since some SUV clown backed into it.
>If you're near Mountain View, CA,
>it's the red one with the silver bootlid.
>
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