How do you adjust timing on a 273?

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Loosen the distributor hold down and turn the distributor.
 
Unplug vacuum advance hose from distributor. Timing light and you should get (or should be) around 16-18 degrees. If not, there is a bolt that goes thru a clamp to hold the distributor in place and you need to be able to rotate the distributor by hand until you achieve 16-18
 
Get a distributor wrench - it'll be much easier to get at the bolt than with any of your regular wrenches.
 
The fun part is you turn the distributor by hand while the engine is running. Any old spark plug wires will be felt and remembered. Ignore the factory specs. As mentioned, more advanced timing is better, though too much initial can make it hard to start (fights starter).
 
The rotor turns clockwise looking down on it. To advance, rotate distributor counter clockwise. The rotor turns once, for two engine revolutions, so distributor degrees times 2, is crank degrees. Make small changes, verify with timing light. For stock base timing, this is often done at correct idle speed, with vacuum advance disconnected and plugged at carb. Consult service manual for procedure, and values. Many advance timing more, and recurve distributor.
 
I left the vacuum advance disconnected on my '67 273 2 brl.. Base timing at about 18 btdc. They say I loose fuel mileage without the vacuum advance but I never pay any attention to that anyway. I go out of my way to get premium grade ethanol free and pay a premium for it, ignore the mpg, ( focused on smiles per mile ). I rarely drive the car anyway but when I do.. I get great throttle response off the stops and enjoy the drive.
I should mention installing the later ( 73 ) model dual plane intake, that 2 brl. carb with the thick base gasket, and the 73 fuel line routing with the inline filter positioned vertically below the alternator also made a big difference.
Electronic ignition with higher output square back alternator also made a big difference.
You might be surprised at what you can get from a 273 with a small investment in used later model parts.
Did I get waaaay off topic here. Yep. My last sentence probably should have been first sentence. Better performance isn't found in timing adjust alone.
 
Before you make an adjustment, put your hand on the valve cover and get a feel for the engine vibration. Now, loosen the distributor hold down JUST enough to allow the distributor to turn. Rotate the distributor counter clockwise until you feel a very noticeable "extra" vibration through the valve cover. It is very pronounced. You will notice it. A blind deaf mute could feel it. Now, back off the distributor slowly clockwise until that extra vibration JUST is gone and lock the distributor down. Drive it. If you don't get any spark knock, leave it there. If you do get spark knock, come back and rotate the distributor clockwise a very small amount at the time until you have no spark knock. Leave the timing light in the toolbox. It just complicates things on a 100% street car.
 
4spdragtop said:
Unplug vacuum advance hose from distributor. Timing light and you should get (or should be) around 16-18 degrees. If not, there is a bolt that goes thru a clamp to hold the distributor in place and you need to be able to rotate the distributor by hand until you achieve 16-18
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Whoah...

Let's not forget that initial timing will change total timing and even more so with a vacum advance distributer. There si nothing wrong with that initial timing but ALWAYS check total.

My advice is to plug off that vacuum advance and just run mechanical advance. Wither way CHECK THE TOTAL
 
roccodart440 said:
Whoah...

Let's not forget that initial timing will change total timing and even more so with a vacum advance distributer. There si nothing wrong with that initial timing but ALWAYS check total.

My advice is to plug off that vacuum advance and just run mechanical advance. Wither way CHECK THE TOTAL
Click to expand...

Timing a mild 100% street car using total timing is a total waste of time. Pun intended. It is not uncommon for a street car with vacuum advance to see 60* total timing with the vacuum advance engaged. Since this occurs only at part throttle, to help clean up emissions that normally would not be burned, there is no chance of detonation. A mild street car will run best with as much initial timing as it can stand excluding detonation.
 
Suit yourself. With an old iron headed engine on today's gas I'll pay the 30$ for a recurve so the timing is correct on both ends of the spectrum. If that is conservative, so be it. I've never grenaded an engine yet.
 
roccodart440 said:
Whoah...

Let's not forget that initial timing will change total timing and even more so with a vacum advance distributer. There si nothing wrong with that initial timing but ALWAYS check total.

My advice is to plug off that vacuum advance and just run mechanical advance. Wither way CHECK THE TOTAL
Click to expand...

I am still getting a grasp on timing as a "whole", so I gave the OP, the 1st step as to what to do. More members on here know a ton more than I do, and I hoped they would chime in. For me it was very confusing on the differing terms that are commonly used when relating to timing. I was gonna say, "All in" and "total" were gonna be next...

To the original poster, does your distributor have vac advance??
What distributor??
Post pics
 
RustyRatRod said:
Before you make an adjustment, put your hand on the valve cover and get a feel for the engine vibration. Now, loosen the distributor hold down JUST enough to allow the distributor to turn. Rotate the distributor counter clockwise until you feel a very noticeable "extra" vibration through the valve cover. It is very pronounced. You will notice it. A blind deaf mute could feel it. Now, back off the distributor slowly clockwise until that extra vibration JUST is gone and lock the distributor down. Drive it. If you don't get any spark knock, leave it there. If you do get spark knock, come back and rotate the distributor clockwise a very small amount at the time until you have no spark knock. Leave the timing light in the toolbox. It just complicates things on a 100% street car.
Click to expand...

LOL This reminded me of my very first car in 1975, 71 Gremlin w/ 232 inline 6 cyl.
Tuning to factory specs didn't run very well.
I rotated that dist' very slowly until the radio antenna stood perfectly still.
That was it's sweet spot.
 
piperdrums said:
Hey guys, great stuff. Yes my distributor does have a vac advance. should I keep it plugged off? a little confusing.
Click to expand...

No, hook it back up, and check that it works. Vacuum advance tunes for the load element. It auto adjusts, advancing timing for light engine loads, no advance at heavy loads, idle, or when starting. You will give up crisp throttle response, light load power, and cruise fuel economy. If you have a weak motor, and drive at wide open throttle all the time, you can get by without it. However with that said, air cooled bugs had only vacuum advance, on many engines.

While a timing light is not necessary, it can help you verify settings, check advance curves and easily return to your setting, or trouble shoot problems. A tach is also handy, both are fairly inexpensive.
 
piperdrums said:
Hey guys, great stuff. Yes my distributor does have a vac advance. should I keep it pluged off? a little confusing.
Click to expand...

I suppose in your case you could leave it hooked up. I guess i'll side with Rusty here.
 
RustyRatRod said:
Before you make an adjustment, put your hand on the valve cover and get a feel for the engine vibration. Now, loosen the distributor hold down JUST enough to allow the distributor to turn. Rotate the distributor counter clockwise until you feel a very noticeable "extra" vibration through the valve cover. It is very pronounced. You will notice it. A blind deaf mute could feel it. Now, back off the distributor slowly clockwise until that extra vibration JUST is gone and lock the distributor down. Drive it. If you don't get any spark knock, leave it there. If you do get spark knock, come back and rotate the distributor clockwise a very small amount at the time until you have no spark knock. Leave the timing light in the toolbox. It just complicates things on a 100% street car.
Click to expand...

I tried this method on my Demon because it seemed to be losing power and not running well. I found the distributor hold down bolt was loose and that was why I guess I was loosing timing. I had bought a timing light prior to seeing RRR's post and having never set timing before was a little intimidated. I decided to try Ratrod's method and set the timing because it seemed so simple. The first time I adjusted the timing I took it for a road test and it had some spark knock so I took it back and adjusted some more and now it runs great! Thanks Rob for posting this method. My timing light is still in the package unopened.
 
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