Total ignition Timing ???

[Jet-PilotTD]

what degree is everyone running (total ignition timing) with there setups ?
I heard the normal is 24 degrees advance

cheers

[LOK15]

On my coupe i opened the gap so it advanced to about 35 , set on 4 deg static , found it revved alot better like this up high ( 6000 rpm ) , but the intake and carbs were choking it at 6400 , would freerev to 7400.

[TURGEM]

if your going N/A ive been told by a few old skool gem racers 36-38 degrees total advance with vac hose diconnected above 3500rpm, you can check it with a timing light with the adjustable retardation,

[Jet-PilotTD]

ok cheers guys

im at 24 degrees total now with vac advance line blocked off
running twin idf 40s and 30/70 cam so its good to know i can get a bit more out of her

[BAD 44u]

N/A quad throttle bodies 32 static upto 10 advance

[canon56348]

any particular reason you have your vacuum line blocked off?

[LOK15]

any particular reason you have your vacuum line blocked off?

Prolly the same reason i have mine blocked , there isnt a fitting for it on the twin manifold.

[BAD 44u]

big cams and webers quads dont have a good vaccum signel due to your only referencing one cylinder

[canon56348]

Hey guys,
With an inline four like the gemi you only have an intake pulse every 180 degrees of crank rotation so the pulses in a single manifold do not "add up" to a great deal more vacuum than one runner. Even if you only plumb one runner to the vacuum can on the dizzy you will be ahead (though you may have slightly better results taking a feed of each runner)
Dude you are absolutely correct about the increased overlap on the bigger cam affecting the vacuum but this is all the more reason to be running vacuum advance on the distributor.
Some race engines running on a very narrow power band disconnect the vac advance because they don't need it, we do. You really don't need a locked advance curve until around 3000-4000RPM due to various factors so prior to this with a locked curve you are now giving away power and fuel economy. Far better of trying to find a "softer" vacuum can than pulls advance at a lot lower setting than standard.

Here is a segment out of a really good article
"When you back out of the throttle the manifold vacuum goes up. This means the compression pressure at the end of the compression stroke is way lower. When a spark timed for a normally fast burning charge (as it is at WOT) fires under these circumstances it is going to occur far too late for the pressure to be at it’s peak at 15 degrees after TDC. This means that less than optimal use of the energy content of the fuel has been made. That in turn means burning more fuel to get the level of power being demanded by the driver at that particular moment. By having vacuum advance pull in appropriately more timing you can let out of the throttle more and consequently cruise on less fuel.
"

here is the link to the article, this guy knows his stuff, we use his products all the time. Well worth the read boys(and girls)
http://classicinlines.com/spark.asp

once you set this up you will need to retime and retune but it will be def worth it. Hope this helps, the more fast geminis out there the better:)

[TURGEM]

vac advance is purely for cruise situations only it has no effect at WOT... the only reason it would pull vacumn at high rpm is due to the inlet tract needs more flow

the only reason ive disconnected mine is I found that it was giving me around 62 degrees advance while cruising, which had destroyed 2 of my motors... Since ive disconnected I havent had any dramas,

[Kiwi_dingo]

On my coupe i opened the gap so it advanced to about 35 , set on 4 deg static , found it revved alot better like this up high ( 6000 rpm ) , but the intake and carbs were choking it at 6400 , would freerev to 7400.

How did it go down low with only 4deg static? My driveability/response starts to suffer when i get below 8deg

[LOK15]

Stall converter, so low revs werent an issue