Wrong distributor for 69 318?
Seems like everything is functioning properly.
Yes. Ported vacuum provides little to no vacuum advance at idle. Chrysler (and many others) used vacuum advance strictly for low density mixtures. In other words, when leaner mixtures were in the engine, light to moderately heavy throttle. At when richer mixtures were called for, idle and full throttle, there was no vacuum advance.
We can see the vacuum advance can add as much as 15*, although the vacuum needed to do so may be something more the 20" Hg. Come back to this later.
Lets look at the timing on the engine and advance in the distributor.
We see the advance curve is just on the low side of the factory specs.
Set at 11* at 700 rpm, its still igniting much earlier than the engine needs or wants.
Given this distributor's advance curve, setting the initial around 5* BTC would put the timing pretty close to acceptable working range. Using premium fuel you could try that and see how it does. If no problems, then you'll have a baseline to work from. Problems that are more subtle than you've experienced so far are light detonation (pinging or gurgling) which under sever load would also show as specs of aluminum on the spark prorcelain.
Just from my experience and looking at hte facotry specs. Highway driving (50 -70 mph, 2600-3000 rpm) the engine should be fine with around 50* while cruising. So lets say you rest the initial so the timing at 3000 rpm ends up at 25 or 27*. With the vac advance connected, the timing will be 50 to 52* while crusing. That should be OK.
Now, if the engine has been hot rodded to some extent, its probably worth reshaping the advance curve because the combustion will be quicker in the mid to high rpm range than a facory 2bbl 318.
Seems like everything is functioning properly.
Yes. Ported vacuum provides little to no vacuum advance at idle. Chrysler (and many others) used vacuum advance strictly for low density mixtures. In other words, when leaner mixtures were in the engine, light to moderately heavy throttle. At when richer mixtures were called for, idle and full throttle, there was no vacuum advance.
We can see the vacuum advance can add as much as 15*, although the vacuum needed to do so may be something more the 20" Hg. Come back to this later.
Lets look at the timing on the engine and advance in the distributor.
We see the advance curve is just on the low side of the factory specs.
Set at 11* at 700 rpm, its still igniting much earlier than the engine needs or wants.
Given this distributor's advance curve, setting the initial around 5* BTC would put the timing pretty close to acceptable working range. Using premium fuel you could try that and see how it does. If no problems, then you'll have a baseline to work from. Problems that are more subtle than you've experienced so far are light detonation (pinging or gurgling) which under sever load would also show as specs of aluminum on the spark prorcelain.
Just from my experience and looking at hte facotry specs. Highway driving (50 -70 mph, 2600-3000 rpm) the engine should be fine with around 50* while cruising. So lets say you rest the initial so the timing at 3000 rpm ends up at 25 or 27*. With the vac advance connected, the timing will be 50 to 52* while crusing. That should be OK.
Now, if the engine has been hot rodded to some extent, its probably worth reshaping the advance curve because the combustion will be quicker in the mid to high rpm range than a facory 2bbl 318.
