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Re: Nth MGB Update

To: "Tyson Sherman" <mts3@ra.msstate.edu>,
Subject: Re: Nth MGB Update
From: "Neil Cotty" <neilc@apphosting.com>
Date: Tue, 21 Sep 1999 10:56:40 +1000
Tyson,

> I followed a timing spec for around 65-70 and set
> it dynamically at 20deg BTDC at 1000rpms.  The car

Well your dist. probably does not have an advance curve to suit that type of
dynamic timing unless it's from a 1970 car, AFAIK they were the only ones to
use a 20deg @ 1000RPM setting (I have a 70BGT). Best to set the thing to
10/12/14 deg btdc at 900rpm or to whatever is spec for your particular
distributor. This alone will lower your idle speed.

What type of carbs are hooked up to your 76? I presume HS4s? Your car must
stop with the idle screws backed out, if it doesn't there's a problem.
Release the accel. cable, and release the clamps on the linkage that sync
the two throttles so you can adjust each carb independantly. If you back the
screws out the whole way and it doesn't stop the motor, then your throttle
plates are not installed correctly, ie they are still open. With the carbs
off you shouldn't see hardly any light coming through with the plates
closed. Have you also checked the throttle return springs? Are they all
there, and hold good tension?

Don't bother with the fuel mix until you're sure the throttle plates are
aok, the valve clearance is set, timing is set to spec. Starting position
for the carbs is two turns down (12 flats) on the mixture adjusting nut,
with the jet initially set level with the bridge.

Tune from there, following the SU manual, Lawrie's great video or get a
Colortune (fabulous device IMO).

Cheers,
Neil.


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