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Hi
playing with timing which I understand s/b 6 btdc which I set and it runs like crap advanced further a guess is to 15 btdc and it runs much much better. starts great and do not hear any ping noise. did not disconnect advance but was at very low idle. should advance be disconnected?

comments please

Ken

In SM electrical section pg 20-21 on dist installation and adjustment, they italicize the instruction about making sure the vacuum line is securely tightened. Later in adjusting the timing, the only instruction or caution they made was to make sure RPM is no higher than the 450-500 range. No mention of disconnecting the advance so I would take it as they want it left connected.

15 btdc ok?

The vacuum take-off port in the carburetor throttle bore will be above the throttle plate if the idle speed is set correctly, hence no need to disconnect the vacuum advance to time the engine as long as the idle speed is correct. But I'm amazed that the car will run well, must less even crank over, at 15 deg. BTDC. I'd suspect the timing marks or pointer are incorrect and the fact that you have no preignition at 15 deg. makes that even more likely. I'd just time it "by ear" and pay no attention to the pointer and marks.

On the 2 bbl carbs I never have a problem setting the timing, but on the 4bbl carbs the vac advance seems to come in very early and I routinely disconnect the vac advance tube for setting the timing--then the idle--then the timing again.

15 degrees is a lot of advance, so I think you are getting a false reading caused by the vac advance having started to pull in already. That or the mechanical advance is not working, or the timing pointer is installed on the wrong pair of bolts on the timing cover.

back to basics

if I pull plug 1 and turn over until the piston hits top I should be tdc or dc which is on balancer, if pointer is off Degree scale should be obvious

Sadly all you will see if you remove the plug is the top of the exhaust valve.

If your pointer is roughly in line with the generator mount it is correct. If it is tucked up under the water pump it is wrong.

update

I am thinking pointer is correct. disconnected advance line attached my 40 yr old + vacuum gauge. 20 pounds steady. need tach but got idle down as low as it will go but not sure actual number. my tim ing light shows me just past scale when I seem to be in the right spot as far as performance goes, no hard crank, no ping, runs much better.
its hard to read the scale is the last number 12? my eyes aint what they used to be. could the weight springs be nfg, might have to pull distrib this weekend and look.

any comments appreciated

wondering

if the distrib set at 6 btdc then upon acceleration the weights advance it x degrees and then vacuum advance kicks it further by x degrees where does that leave me degree wise?

A good question I'd like to know more about too. In the case of the Delco, limits are 16 centrifugal and 10 vacuum. Do the two work together within the 16 degree range or can the dist go to max advance on each one for a total of 26

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