kalli

Hi all,

I keep playing with it. I advance, I retard, I change springs. The car runs good, but I'm pretty sure if I hit it, it'll be better.

What I've done so far. I timed according to strobe anywhere around 6-10 degrees.
I couldn't tell much difference between 8 and 10 and my ear seems to be deaf for pinging. I just never heard an engine ping, so I can't use that as a tuning tool.

So reading up upon manifold vacuum I never could figure how I could measure this with my autolite 2100. Until yesterday it struck me.
The choke heater. It's not hooked up anyway (i have taped it closed). So I hooked my vac gauge up there and found that I seem to get manifold vac reading here.

Curb idle seems fine, so I adjusted the idle screws to just where vac drops and a quarter turn out.
This is the same setting as my ears are telling me. open 3 turns and close. when rpms drop, open quarter turn. So no difference there.

My pertronix distri came with 2 springs (medium) medium pre-installed.
When I check with my strobe and vac advance unhooked the advance doesn't advance until I rev to about 1600rpm.
So I changed one of the springs to a lighter one and now it seems to start at 1100 rpm (i think much better).
Total advance is around 38 degrees at around 2500-3000 rpm (i don't want to rev that high to check exact number for log for my neighbours sake)

So then I tried to adjust initial advance with manifold vac reading. I advanced to about 20 in idle and then retarted until vacuum just starts to drop. According to my strobe this is 13 degrees. I have it set to this but not test driven yet.

Are there any other suggestions or ideas or performance reports on what values seem to work with a stock 289 2barrell, headers and flowmaster. Did anyone play with the springs, which ones seem to work best for you?

Any comments or ideas let me know (i'm sick of trial and error)
If anyone knows how to produce a ping so that even my ears get to hear it let me know ... ;-)

Kalli

bradleyb

keep advancing the timing a few degrees at a time until it pings under load. Then back off the timing a bit and you should be sorted (the pinging represents being too advanced - I believe the concept is that there isn't enough compression at the time of spark to burn all the fuel in the cylinder but its been a long time since auto shop).

another trick that a guy at the local mustang shop told me - with the engine off,turn the crank until the mark is over the appropriate timing mark just before TDC - so if you wanted 8 degrees, the pointer would be pointing at 8. Then take out the #1 spark plug and hold it about 1/8" away from the engine block - rotate the distributor until you see the blue spark arc at the spark plug and you should be set (he says that he never uses a timing light and has always had good luck).

kalli

Hi Bradley,

thanks for the response.
the first idea sounds great, but I never heard this pinging. I seem to be deaf to it. I went from 13 back to 10 and it runs the same good or better. I get the exhaust rumblling a bit when i step off the gas which it doesn't do with 13. my car is very silent at 13. don't like that ;-) as for accelleration i can't tell a difference between 10 and 13 initial

as for the trick you mention, that's called static ignition adjustment.
It works the same way with a testlight at the breaker point. when you turn the distributor until the light goes off, this means the breaker opened--> ignition

Dynamic timing is by far more accurate, but my problem is not to adjust timing to a certain point, my problem is finding the exact point ... as in:
will I need 8 or 11 ot 13 initial advance
will i need the low/med spring setup or should I go back to med/med

I'd really love an audio recording where you could hear the pinging
maybe I set it to 15 next and see if I can hear it then ...

Kalli

iamdiffrnt

The pinging sounds similar to a slight exhaust leak (just enough to be annoying), or lifter noise. Just a tapping coming from the engine compartment when accelerating, but usually goes away when you let up off the throttle.

Hope this helps.

kalli

thanks a lot. I'll listen out for it again. it definetly helps as 'slight exhaust leak' and 'lifter noise' is far away from a 'ping'

jlg2002

Pinging sounds like a rattling marbles in a can noise.

kalli

hmmm i'll watch for marbles, whistles and exhaust leaks next time i take her out.
that sounds fun :-)