timing 1960

[Michael B.]

Hello, can someone refresh my mind on the proper way to set timing and dwell on my 1960 283 single four barrel single point distributor.( you disconnect vacuum advance and plug while setting timing right )thanks michael

[William C.]

Re: timing 1960

Disconnect vacuum line and plug, set DWELL first, then set timing, reconnect vacuum and off to the cruise-in or whatever.

[Joel F.]

Re: timing 1960

Following Bill's instructions, if you have a dial back light, I would only add that it may be helpful to set the total timing to around 36* when all in (3,000 rpm or so?) instead of setting the initial timing per the ST12.

IMHO the initial timing is almost meaningless in these cars since the mechanical advance weights and springs have likely been monkeyed with at some point. Once you set the total advance, you can observe the initial advance for future use, since the mechanical curve will stay the same.

[Michael B.]

Re: timing 1960

joel, so your saying set at 36*with advance hooked up and rpm's at 3000 (right)thanks michael

[Joel F.]

Re: timing 1960

joel, so your saying set at 36*with advance hooked up and rpm's at 3000 (right)thanks michael

Not exactly Michael . . . you set it at 36* with vacuum advance disconnected and plugged. What you want is around 36* of total timing with vacuum disconnected when the centrifugal advance is "all in". For most people the mechanical advance comes in completely by 3000 but you will need to verify this when adjusting your timing by going past 3000 and observing the balancer and timing tab with your timing light.

Does this make sense? If not I can try to explain in more detail. The vacuum advance is not really adjustable per se. To change the way it interacts you'd need to change the actual vacuum cannister on the distributor.

[Duke W.]

Re: timing 1960

joel, so your saying set at 36*with advance hooked up and rpm's at 3000 (right)thanks michael

36 degrees total WOT advance may be a bit high for a 283 due to the smaller bore and chamber compared to a 327 or 350. Check your documents to see what the total centrifugal plus initial is. This sum is probably closer to 32.

Checking total WOT timing with the OE centrifugal curve is not for the faint of heart in some cases because the engine must be revved to beyond the point of maximum advance which can be as high as 5000, and a lot of guys don't like to stick their heads into the engine compartment with the engine making 5000 revs.

Unless you're experienced in taking ignition maps with a dial back light, just set the initial timing as Bill previously recommended. OE initial timing is typically conservative, and as a rule of thumb you can set it 2-4 degres higher than "spec", which might improve performance and fuel economy slightly as long as there is no detonation.

Setting initial or total WOT timing should always be done with the VAC disconnected. Once the distributor is tightened down, connect the VAC and verify that the total VAC advance is added, which is typically 16 degrees (check your specs). This is the "total idle timing".

Duke

[Arland D.]

Re: timing 1960

Setting initial or total WOT timing should always be done with the VAC disconnected. Once the distributor is tightened down, connect the VAC and verify that the total VAC advance is added, which is typically 16 degrees (check your specs). This is the "total idle timing".

Duke,

Just wanted to clarify in my mind whether the "typically 16 degrees" is strictly just the amount of stand alone vacuum advance being added or the result of the vacuum advance plus initial advance. Thanks,

Arland

[Duke W.]

Re: timing 1960

Setting initial or total WOT timing should always be done with the VAC disconnected. Once the distributor is tightened down, connect the VAC and verify that the total VAC advance is added, which is typically 16 degrees (check your specs). This is the "total idle timing".

Duke,

Just wanted to clarify in my mind whether the "typically 16 degrees" is strictly just the amount of stand alone vacuum advance being added or the result of the vacuum advance plus initial advance. Thanks,

Arland

The "typically 16 degrees" is the maximum advance added by VACs, and the total idle timing should typically be the sum of initial and full advance from the VAC. There are some exceptions, like the 30-30 cam engines that have centrifugals that start at 700, but they won't idle that low with acceptable quality, so the total idle timing is the sum of initial plus full vacuum plus a few degrees of centrifugal at 900.

If you have a dial back timing light and want to diddle with your spark advance map the first thing to do is get the OE specs for your specific engine.

Then use the dial back light to test the map to see if it comforms to OE specs. It may not because it has been previously modified or is not functioning properly. You also need a vacuum pump or gage to test the VAC.

In most cases OE engines will tolerate a quicker centrifugal curve and a little more initial timing. Spring kits are available and it's a matter of experimentation, and if you know what you're doing, you can set it up at the ragged edge of detonation, which will yield the best performance and fuel economy.

I just recently did this to my '88 Mercedes 190E 2.6 5-speed after finally figuring out how to alter the centrifugal curve. (The initial timing cannot be changed.) It's done with a trim resistor attached to a pigtail in the engine wiring harness. By going with the most aggressive curve (zero resistance by just removing the resistor) my around town fuel economy increased 10 percent and the engine feels considerably less "torque shy", which was always a problem.

In many around town driving situations I can now run one gear higher and still have acceptable engine response because the engine is now operating at a higher thermal efficiency level at light load/lower revs - more power with less fuel. The price is a bit of transient detonation with my usual short shift driving technique.

I can "drive around" this by either feeding the throttle in more slowly in the next higher gear or shifting at higher revs. I am at the ragged edge of detonation and can tell because it's very sensitive to both ambient and coolant temperatures. At 70F ambient (or below) and 80C coolant temperature, there is no detonation. If either is just a few degrees higher the transient detonation is audible. That's the ragged edge of detonation! But since I only drive this car from November to May... If I drove it during the summer I would probably have to slow down the centrifugal curve by installing the OE trim resistor to keep the detonation under control.

For emission testing I install a shorting plug which results in the slowest centrifugal curve. It can barely get out of its own way below 2000 but the hydrocarbon readings are 40 percent lower. They were near the limit with the OE 750 ohm resistor. Retarding the centrifugal raises EGT considerably (but just kills the torque), which keeps the converter hotter and more efficient during the loaded dyno test, which is run at about 1600 RPM.

One of the best aspects of vintage cars is that the spark advance map is determined by simple mechanical and vacuum systems that are easy to understand and change. Modern car's electronic systems can represent a real challenge when attempting to do performance or emission tuning.

Duke

[Michael B.]

Re: timing 1960

Duke,I used to race cars and thought nothing of sticking my head in and reving engine 5000,6000 thousand to set timing,but that was a few years ago and the biggest problem I have now is (remembering were I put my timing light) thanks for the info, michael