59 Timing Question

[Jill J.]

[Joseph L.]

Re: 59 Timing Question

Hi Jill
For a 60 year old car that may have had the distributor changed in some way, the initial timing is not a concern. You need to find the RPM that maximum mechanical advance occurs, then add a couple hundred RPM to that and set the total mechanical advance at 36-40. That may be 3000-4000 RPM? A dial back timing light is very helpful.
Initial advance to arrive at 36-40 total is going to vary depending on the RPM that advance starts at, and whether your car will idle at a lower RPM.
If the initial advance starts at 700, and you have it idling at 850 like I do, your car is already on the advance curve.
Also, without vacuum advance, you need early/ more mechanical advance to allow the engine to run cooler.
Joe

[Jill J.]

Re: 59 Timing Question

Hi Jill
For a 60 year old car that may have had the distributor changed in some way, the initial timing is not a concern. You need to find the RPM that maximum mechanical advance occurs, then add a couple hundred RPM to that and set the total mechanical advance at 36-40. That may be 3000-4000 RPM? A dial back timing light is very helpful.
Initial advance to arrive at 36-40 total is going to vary depending on the RPM that advance starts at, and whether your car will idle at a lower RPM.
If the initial advance starts at 700, and you have it idling at 850 like I do, your car is already on the advance curve.
Also, without vacuum advance, you need early/ more mechanical advance to allow the engine to run cooler.
Joe

Thanks Joe. We'll give that a try tomorrow. Appreciate you taking the time to respond.

Jill, 59140

[David M.]

Re: 59 Timing Question

A vacuum gauge is your friend.
Hooked to a straight manifold source adjust the A/F ratio and timing(back n forth) to obtain the highest possible vacuum reading at curb idle.
Use a timing light to verify and record that data. You should know what the vac and centrifugal events are as well.

Basically give the engine as much timing as it will tolerate before pre-ignition occurs.
If its running hot verify the vac advance is working and your cooling system doesn't need attention.

Conclusion:
Base timing @ warm curb idle - 10-14*
Vac advance - another 8-10* at warm curb idle.
Centrifugal should come in at a given RPM transition off idle (12-1500ish) and be all in at a max RPM. For a BB all-in around 2700-3000. Slightly higher for high winding SB.

The timing events are not standard. The spec is a good starting point...most of the time.
Each engine is different Some like 36* total some like 42* Depends on how far above sea level you are, fuel octane, driving habits etc...
Let the vacuum gauge tell you where it wants to be.

Experiment and see what it likes.

Make sure all serviceable/perishable ignition/fuel system parts check OK before attempting any adjustments.

Make sure the point dwell is set to 30*

Dieseling causes:
- cylinder/piston carbon build-up
- boiling fuel
- heat soak
- fuel dumping out of the carb(s) by defect or wrong adjustment.
- curb idle RPM set to high.

[Frank D.]

Re: 59 Timing Question

My 61 with the same, original motor came with a dual point distributor with no vacuum advance (I added a different distributor with vacuum advance later)...and, using a dial back timing light. 12* at about an 800 RPM idle, 18" of vacuum, and 38* at 2600 RPM (vac advance plugged in both cases). An aggressive setup but the car ran with this configuration for 8 years flawlessly. There are other factors that can be causing your dieseling - like too fast of a curb idle, too hot of a plug selection, etc. I eventually settled on the NGK-B4 plug as a compromise. More reasons in the prior post. I would "de-carbon" the engine as suggested above as a first step and there are several ways to do that.

Are you running true 270hp carbs or clones and how do your plugs look ?

[Duke W.]

Re: 59 Timing Question

Hi Jill
For a 60 year old car that may have had the distributor changed in some way, the initial timing is not a concern. You need to find the RPM that maximum mechanical advance occurs, then add a couple hundred RPM to that and set the total mechanical advance at 36-40. That may be 3000-4000 RPM? A dial back timing light is very helpful.
Initial advance to arrive at 36-40 total is going to vary depending on the RPM that advance starts at, and whether your car will idle at a lower RPM.
If the initial advance starts at 700, and you have it idling at 850 like I do, your car is already on the advance curve.
Also, without vacuum advance, you need early/ more mechanical advance to allow the engine to run cooler.
Joe

What Joe said. From memory your OE centrifugal is 28 max at about 3500, and it may start as low as 700, which is below what that engine will idle at with acceptable quality, but you need to document what the actual centrifugal is with a dial back timing light and look at the AMA specs to verify the original spec.

It would be a good idea to install lighter springs to start centrifugal sooner and get it all in sooner. With only an advertised CR of 9.5:1, which may actually be lower a lot of 270s run detonation free on 87 PON fuel and higher octane will allow a very aggressive spark advance map.

A high overlap cams like the Duntov idles best with around 30 degrees total idle advance, but with no vacuum advance all you can get is initial plus maybe a few degrees centrifugal if it starts below idle speed. Less that optimum total idle advance means higher EGT, which throws more heat into the cooling system. If manifold temp is more than 500F total idle advance is less than optimum, but there's not much you can do without a vacuum advance.

Duke

[Jill J.]

Re: 59 Timing Question

My 61 with the same, original motor came with a dual point distributor with no vacuum advance (I added a different distributor with vacuum advance later)...and, using a dial back timing light. 12* at about an 800 RPM idle, 18" of vacuum, and 38* at 2600 RPM (vac advance plugged in both cases). An aggressive setup but the car ran with this configuration for 8 years flawlessly. There are other factors that can be causing your dieseling - like too fast of a curb idle, too hot of a plug selection, etc. I eventually settled on the NGK-B4 plug as a compromise. More reasons in the prior post. I would "de-carbon" the engine as suggested above as a first step and there are several ways to do that.

Are you running true 270hp carbs or clones and how do your plugs look ?

Hi Frank. Yes these are true 270 up carbs and my plugs are brand new. I have only used them during the initial break-in and the little bit of trying to get my engine tuned properly. So I might have about 1 hour on everything including my engine (it's a 519 block bored at 30 over).

Jill, 59140

[Jill J.]

Re: 59 Timing Question

Thanks for all of your responses. We are going to try each of the comments posted and see what works best. Will send an updated post once we get it figured out.

Jill, 59140