set ignition timing with vac gauge

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steve00136
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set ignition timing with vac gauge

Post by steve00136 » Wed Apr 10, 2019 11:32 pm

Well i have read a lot about how you should ignore manufacturers settings which was based on a totally different 1970s leaded fuel and use a vacuum gauge to set timing and not a strobe. I connected my Gunsons vac gauge up after slackening the distributor clamp and as soon as started engine the gauge was showing retarded timing (even though it was set at the prescribed 10deg). I advanced the timing bit by bit. Vac went up and so did tickover speed until it levelled out at 20" so retarded it 1" on the scale which measures in inches. Disconnected and went for a run and a massive difference in acceleration and sounds smoother. On return out of interest i connected my timing strobe and found it was now 20 deg advanced. Seemed a lot to me but will run it and monitor for any pinking.
steve livesley
Nottingham UK
1975 MGB Roadster
my blog:- https://mgb.tips collected from all across the Internet

Vic Butler
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Re: set ignition timing with vac gauge

Post by Vic Butler » Thu Apr 11, 2019 7:39 pm

Not come across this method Steve. This may seem like a daft question but where was the vacuum gauge connected? I presume it was to the vacuum take off point on the carburettor.
I'd like to give it a try, more information please. My BGT has no vacuum advance mechanism on the distributor now.
1977 Stage 2 MGB GT
1975 SWB Series 3 Land Rover with a later 2.5 petrol engine

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steve00136
Posts: 30
Joined: Sun Dec 30, 2018 9:11 am
Forename: Steve
Surname: Livesley
Location: Nottingham
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Re: set ignition timing with vac gauge

Post by steve00136 » Thu Apr 11, 2019 11:53 pm

I've got a load of info on this is done on my blog at http://www.mymgb.info
steve livesley
Nottingham UK
1975 MGB Roadster
my blog:- https://mgb.tips collected from all across the Internet

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