Too Much Advance?

[Junior64]

I have a '64 Falcon 170 and my timing is set a few notches past the gauge. I'm guessing around 16 degrees or more. Everything is stock including the Load-O-Matic and 1100 carb with SCV. I verified TDC to make sure the balancer was not off. There is no pinging under load and it has the most power/response with this setting. Is it uncommon to have the timing advanced so much?

 

[bubba22349]

Is it uncommon to have the timing advanced so much?

The short answer is No! Some people used to advance until the starter kicks back and than back it off just enough so it starts easy. If it's not pinging

 

[fordconvert]

Yep if it starts no ping and seems to perform good then just be happy. It is worth taking note of what the timing readings vs. rpm are just so if performance changes you can check and see if that is what changed or if you replace any parts you can get back to where you started.

Lots of things could cause the engine to run well with the timing off. Of course slipped or miss matched balancer could cause it but also things like the cam timing. That could be just the spec of the cam. It could be loose or the timing on the chain. I had an engine that according to the marks was running good at around 2* ADC. I just assumed it was miss match in the pulley or marker and since it ran good I never bothered to measure or verify it. An unrelated failure (oil pump) caused me to have to tear it apart and I noticed that the cam timing was off. Getting it correct did not change the performance much but it did get the timing marks back where most people considered it normal.

Did you use a piston stop and degree wheel or mark off the pulley to verify your marks? That is the only way to verify actual TDC. If you just eyeballed it with a piece of wire or something similar you are likely +/- 10 degrees.

 

[JackFish]

Is it not normal for SCV setup to be pulling a good deal of vacuum at idle?

 

[bubba22349]

Is it not normal for SCV setup to be pulling a good deal of vacuum at idle?

There should be none or very little vacuum at idle with carb idle set properly at about 500 rpm, the throttle blade almost closed! The SCV works quite different from the later style vacuum advance units

 

[JackFish]

Yes it does, in that it's controlled by manifold vacuum.
Which is why I thought that it would provide advance at idle.

 

[Junior64]

Thanks for all the replies. I have the RPM at 700 instead of the factory setting which does give me some vacuum advance. I set my timing with the vacuum line hooked up since I have vacuum with the increased RPM.

 

[Eaglo]

I went through this same situation just a couple of weeks ago; my posts are here somewhere.

My engine had a trashed vacuum advance, and someone had advanced the timing about 35 degrees. It ran fine. It took a new set of points and condenser to get the timing closer to normal.

Then, after replacing the Loadomatic advance, I was pulling about 3 degrees of advance (maybe 2" of vacuum) at idle. From what I had read of the setup, I thought this was wrong and did some research.

After looking through all the Loadomatic specifications, I found many engine/carb combinations that were supposed to show some vacuum advance at idle. There are at least a dozen combinations for '65 and a couple of them show a few degrees of advance with the throttle plates at idle.

I have an Econoline truck, and that carburetor actually has two vacuum holes in the venturi -- one above and one below the closed throttle plate.

The manuals also instruct you to advance the timing as much as possible without pinging for increased performance.

So based on my experience and what I've read, your situation seems fine.

My basic timing is about eight degrees with the vacuum line disconnected. When it's connected at about 700 RPM, I'm seeing about eleven degrees. Any more than that and it pings like mad crazy when it's hot and accelerating.

Best of luck.

 

[Junior64]

It's weird. My engine doesn't ping when I advance it too much. It just runs rough.

 

[fordconvert]

No ping could be because

-low compression either dynamic or static

-odd cam timing

-very rich (which usually wont last for long because rich will build carbon which retains heat which promotes detonation)

-things are very smooth clean and cool

 

[MustangSix]

I used to think that optimum advance could be set by pulling timing back until the engine stopped pinging. But from what I've been reading that may still be too much for best power and performance.

You may not get an audible ping, but you could be starting the fire too soon, losing some power as the piston uses power to compress against the burning fuel and air. Lighting the spark a little later would still result in a complete burn, but would use less energy during the compression stroke. A dyno would be the best measure, but you could probably do some road tests as well. Just some simple timed acceleration runs might be good enough to tell if you actually gained power with more or less advance dialed in.