how would one go about adjusting the timing for a carbed car without using a timing light?
have two different cars here one was running ok without any ping but found out the vac can was torn so it wasn't advancing the timing for cruising. still was idling nice and smooth though. so we replaced it and then the car started to ping like a mother fricker and when you tried to start the car up it just sat there and spun hella fast like a car does with the timing too far retarded.
we sswapped the vac line out for a ported vac line and now it doesn't ping when under load but the idle quality sucks and we where able to advance it quite a bit more and it has the power back it should more or less but still can't get a nice asmooth idle

the other car I'm just trying to get timing as best as I can without a timing light since I don't have one handy

 

if you can get the car on... get until the car sound that it is running right .... . but you really should borrow one or buy a timing gun... makes easier...

 

I would start by getting it to sound as good as possible in the driveway. Then go for a drive and then advance it in small increments until it starts to ping just a little and back it off a touch from there.
The old school hot-rod trick I got from my G-Dad who got it from his Dad is to advance the timing on old cars until they lightly ping only under a heavy load that you would never actually encounter. Like punching the gas while lugging the engine in top gear while pulling a hill. That 's the max timing that's safe to run.

What is your idle RPM at? It may have been idling higher due to the line being torn and causing a vaccum leak. Now that you've plugged it, the engine may be idling too low.

 

Can someone give a quick definition of a "ping"? Curious.

 

Ping is the sound that detonation (fuel autoigniting after the main inake charge has ignited) makes. Mild detonation is literally a 'Ping' sound. Harsh detonation is more like a bunch of hammers flying around in the motor.

Id avoid tuning by detonation alone. Its easy to run too much timing. The idea is to run just the right ammount of timing so the mixture is done burning shortly after the piston passes TDC. Id start a tad on the retarded side and advance the timing untill the performance plateaus (or untill detonation is reached) and leave it there.

 

The vacuum method is as follows. Advance timing to the point the vac guage peaks then starts to decline. Return to that peak, then retard the timing 2 more inches of vacuum and your set.

 

sounds good to me scc
cause yeah we tried to adjust by peak vac before and all we did was get ping like a mother under any sort of load and the power band SUCKED ***** down low up top and midrange it seemed to have a little moer but wasn't worth it

 

Would the vaccum port that leads to the THERMAC device be a good reference point for tuning?

 

As long as the other end gets full manifold vacuum.