Hey guys, have just modified a sentra dizzy for the coupe, and was hoping some of you guys could help me out with the right ignition timing setting for a modified A-series. I was thinking 32-34deg BTDC, but was a bit worried as the old Nismo catalogue says something about 40 degrees? I have to limit the advance as the std e15 dizzy advances WAY too much.

Engine is 11.75:1 running on 100 octane.

Cheers fellas.

what sort of racing ? circuit , speedway , drag?
speedway you could lock it at 30 deg and forget it.
but circuit needs more driveability, alot of mechanical advanve is not always a bad thing try to map out how much mech. adv. it has then you can work out what the idle adv. would be for any given total adv. setting
eg.a dizzy with
34 deg total
- 20 mech. adv.
= 14 deg at idle

it also depends on the burn rate (combustion efficiency)

I have a bosh high energy disy off a bluebird in my A14 & run 15deg @ idle with no vac advance & has never pinged or has been hard to start.
Have you had the dizzy set up to suit your engine specs? The dizzy builder shoud tell you where to set it.
Mark

Setting it up is what I'm doing, I'm the dizzy builder
15 deg at idle and it's not hard to start? Really???
It is a club car, mainly circuit and hillclimbs. Having no advance is definitely not an option.

comon guys some of you racers must surely be able to share your secrets...

nzdatman i dont race with my motor but its pretty much a stage2 motor with head, valves, cam, bore etc modified. im running about the same compression and same octane.
i changed my timing this weekend and found it was set at 20degrees! i put it back to 15 and its been running better and easier to start too. im using a modified n12 pulsar elec dissy. not using vacuum plug on dissy. revs happily out to and past 6 (where i usually slow down since im on a public road)

Its a difficult one to answer. The setup of your engine, cam choice, fuel/air mix quality, mixture, squish clearance and other things will affect this figure quite considerably.

It think 30 degrees max is a good place to start. 40 degrees is ok for race prepe'd 10,000 rpm A13's with forged pistons, but probably a death setting for a more common type of modified engine.

I set mine for saftey but ive welded up the advance slot to give a total of 15degrees in the dizzy but i do run 15 static

I found the extra static helped it to start but then i have less comp

I run mine on 17 degrees for 98 octane so maybe 20 degrees would be about the max I'd go......

It's also dependant on how much detail work done to the combustion chambers.