Ignition timing question

[agr071]

SO, after looking at several different forums, it's hard to gather which is the correct and best way to have timing on a 308.

Have read to:
a) set timing at anywhere between 6 degrees and 12 degrees
b) run full advance (manifold) or carby advance.

NOW I currently have it about 8 degrees and no vac advance at all and have an auto (not real responsive and seems to lack a bit of grunt. If it's set at 12 degrees it pings).

So can someone PLEASE tell me the best way to have it?

Thanks

[Beachy]

We used to run the vac advance we would advance it up to ping then back it off til it stopped pinging and run there cannot remember exactly but around 9 or 10 degrees before tdc

[Vombil]

my experience is that some some are easier than others. some i've never been happy with. I think its a combination of a lot of things ie fuel, carby, ignition

i can also say that i've never had a vacuum advance that seems to work (made no difference to timing when it was blocked off or not)

6-8 seems to work for almost any holden motor. maybe your balancer has spun. i had an HZ 253 performance engine that suffered this. carby bloke i use reckons he's seen quite a few of it over the years

[bobsmith380]

6 - 8 deg before TDC. Vac advance direct to manifold. And Run 95 or 98, preferably 98 in it.

[Big Rob]

6 - 8 deg before TDC. Vac advance direct to manifold. And Run 95 or 98, preferably 98 in it.

As is often coincidental, I did the timing on the HZ this morning after replacing the distributor cap, rotor, points & plugs.
Points at 15thou, plugs at 35thou, ignition timing at 8deg advanced at idle with vac advance disconnected and plugged.
After reconnecting vac advance and deleting the stupid plastic restrictive green and white thing that was between the vac source and the distributor it goes like it should. The restrictor thing was stopping the timing advancing when the engine was revved.... no such issue now.
And as Bobsmith says... 98 only plus valve saver.

[Dr Terry]

It depends on several things. Firstly, does the car have auto or manual trans & is the cam, carby & exhaust factory stock or modified.

If it's basically stock, the vacuum advance can have full vacuum at idle if it is an auto, but the vacuum should be 'ported' if it's a manual.

Next is the basic timing, HQ/HJ were set at 6 degrees initial, but this was different for HX/HZ. I've found that if you're using 98 fuel (which you should be BTW) 8 degrees is a good starting point & you can advance or retard from that point by listening for pinging.

If you are running a different cam, carby or exhaust, then a different mechanical (centrifugal) advance curve is required. No amount of changes to initial timing will overcome the problem. With the wrong curve, if you retard the distributor enough to eliminate pinging then you lose power. You can't have both.

Dr Terry

[Vombil]

If you are running a different cam, carby or exhaust, then a different mechanical (centrifugal) advance curve is required. No amount of changes to initial timing will overcome the problem. With the wrong curve, if you retard the distributor enough to eliminate pinging then you lose power. You can't have both.

Dr Terry

^^^^ yeah, what Terry said

[panoz78]

.

If you are running a different cam, carby or exhaust, then a different mechanical (centrifugal) advance curve is required. No amount of changes to initial timing will overcome the problem. With the wrong curve, if you retard the distributor enough to eliminate pinging then you lose power. You can't have both.

Dr Terry

Getting the dizzy regraphed is the most overlooked thing when most people play with there engines,
I've had mine regraphed several times .
I have also found that the best way for me to set the timing is to have it at 3000rpm then set@ around 34degrees advanced then play with it from there going up /down looking for a maximum power with out pinging,My harmonic balancer is marked a full 360 degrees...

[agr071]

Thanks for all the input.
Because it's an Auto, I set the timing at 6 degrees.
I adjusted the mixture screws to get it to idle smooth. (About 3 turns out each).
Then I connected manifold vacuum and i've adjusted the idle down to about 800rpm in Park.
ANOTHER thing i noticed is that the accelerator pedal, even though it hit the floor, only operated about 3/4 of the carby and wasn't bringing on the secondaries. (I've got them adjusted to come on a bit later).
Re adjusted that and once I get a new battery i'll be able to take it for a drive.

(Next job is to fix the backlash in the diff).