Timing issues?

[brummiewedge]

Hi Guys, the 4.6 is well and truly up and running, but what are other people experience as regards the timing settings? one of the things is do you use the vac advance or not? It seems without this you can run a more advanced fixed setting. As when you hoof it at low revs with it connected it pinks with 6 degrees advance, and without the vac pipe connected it does not. Tickover is smoother with more fixed advance too. ( Lumpy cam.)

[rev-erend]

Brummie - I was advised to set the timing at 32 degress at 3000 rpm
(vac disconnected for this) .. I guess the theory being that timing is more accurately set in the midrange than at tickover..

Have not got around to do it yet myself though..

[shpub]

There are no magic figures in reality as the timing should be set up with the aid of a gas analyser to work out what the optimum is. The figures are really no more than guidelines and are not really set in stone. Whether you use the vac advance or not is really one of whther it helps with the tuning or not. In some cases, it can be better with it removed.

[v8 racing]

basically if you are running a hairy cam disconnect the vac pipe as this will make the low speed cruise much smoother, basically what you are doing is, retarding the ignition but opening the throttle more so you are getting air speed through the ports hence a nicer combustion and nicer to drive, you will use slightly more fuel but this is negligible, on all the rovers i have built peak power has always occured between 28-30 deg max advance at 4000 rpm, forget the idle advance it is meaningless check at full advance, for the sake of security always go for 28 deg 30 might give you 2 more bhp but could detonante in the summer

[brummiewedge]

Thanks V8, much as i suspected from my arse dyno!!
Will ditch the vac tommorow, so you say hold at 4000rpm and set to 28 degrees?

[chunder]

v8 racing said:

basically if you are running a hairy cam disconnect the vac pipe as this will make the low speed cruise much smoother, basically what you are doing is, retarding the ignition but opening the throttle more so you are getting air speed through the ports hence a nicer combustion and nicer to drive, you will use slightly more fuel but this is negligible, on all the rovers i have built peak power has always occured between 28-30 deg max advance at 4000 rpm, forget the idle advance it is meaningless check at full advance, for the sake of security always go for 28 deg 30 might give you 2 more bhp but could detonante in the summer

Invaluable V8 - thanks.
Have always had what I thought was an over-fuelling issue under 3000 - took it out today and tried disconnecting the vac advance just for the hell of it. What a transformation - smooth cruise now (still dodgy below 1800 but livable) much more drivable and what seems like a huge gain in torque !
Any more nuggets ?

[v8 racing]

Lots more but that would be telling now wouldnt it!!

[badredwedge]

So will these settings work for me on my standard 400 hotwire ??

[cuneus]

v8 racing said:

Lots more but that would be telling now wouldnt it!!

Lots of at the BBWF ??