So I have a 68 289 the rest of the specs are in my signature below
TLDR:
-what should the initial and advanced timing be.
-is there even a concrete answer when it comes to timing?
-should the vacuum advance make the car sound different when it’s unplugged/capped/plugged?
Long winded story:
So I got the new carb/fuel system in place and “did the timing” there is a yellow mark at 0 on my harmonic balancer but from what I’ve read most 289s should be at 10-12. I’ve also heard/read that they should be at 6 with California gas. I’ve heard as well that it is a preference and should be done by ear/when the engine doesn’t shake… so looking for some more advice on how I should go about setting the timing. Really hoping for some solid advice, cause the car has slight overheating issue as well. Vacuum was down in the 14s and slightly jumping around where my brother liked it not even sure where he set the timing cause he kept messing with it. Also we never set the advanced timing which I couldn’t find a concrete answer on what that should be at. Also have heard the distributor makes a difference on what the timing should be. Not even sure what kind of distributor I have but it was a stock replacement most likely from an auto parts store post engine fire 10 years ago. Also the vacuum advance does not make a difference in engine noise when it is unplugged/capped/plugged even during running.
The timing thing is something of a guessing game as there are a ton of variables. Is the cam stock ? Is it installed straight up ? Do you have CA emissions on the car originally ? What condition is the motor in ? New ? Well worn ? Blowing oil ? New carb you say … is it dialed in or are you still tuning on it ?
Typically 6° is the factory spec and it will run pretty smooth there. Most find up to about 14° or so on the base gives better performance, but of course too much can cause hard starting, pinging/knocking, and potentially overheating.
Ages ago I started a page on how to tune using a vacuum gauge, but basically you want to maximize the vacuum and then probably back it off a couple of degrees to avoid pinging/detonation issues and such.
If the vacuum is low and jumping around you likely have another issue going on as well. The vacuum should be fairly steady so check for vacuum leaks and misfires.
The advance is likely hooked up to “ported” vacuum which is just above the throttle plates on the carburetor. That means it won’t see any vacuum until the throttle is opened slightly. Depending on options and things there may be a vacuum tree on the thermostat housing that has one hose from ported vacuum and another from manifold vacuum with the third hose going to the distributor. This allows the motor to switch between the vacuum sources depending on temperature.
Cam is stock to my knowledge, the engine has 50-60k miles on the rebuild and does not burn oil out the back. What do you mean by installed straight up? the cam? The car was built in San Jose so most likely CA emissions not sure how to check that. I don’t need to get the car smogged I know that. The carb is definitely not dialed in I was told to properly set the timing before I dial in the carb but I briefly set the mixture screws for an economy idle at 750rpm.
Alright I think I’ll try setting it at 6 and 10 and see how it looks and sounds. I’d like a more well rounded tune I want the car to run safe and smooth as the priority but with a slight edge on stock base 289s hence the small upgrades I’ve done.
If I’m not happy with a 6 or 10 then I’ll try the vacuum way. It was at a solid and steady 18-19hg at one point but my brother didn’t like how it sounded. I plugged the vacuum gauge in before the check valve so it should not have been a leak. Everything was capped and the brake vacuum was capped with threading tape.
Ok so that would explain why the advance wasn’t sounding different with it plugged in or out. Is that why I should check the advanced timing? what rpm should that be done at and should it be the same as the initial timing?
Not sure about the manifold vacuum it has one connection near the back of the manifold that goes to both the transmission and check valve/lights. Then the distributor is hooked up to the ported vacuum line from the edelbrock carb. The pcv/hose was also replaced and snug in some new valve covers.
Thanks so much for the long winded response! I really want to know as much as I can about the subject. I was struggling to find solid info.
edit: not sure if I mentioned but I did do the timing with the advance vacuum unplugged
I was referencing the cam being installed straight up. Without knowledge of what’s inside the motor I would assume stock initially unless you can prove otherwise. Many times an advertised rebuild may be just new paint or new gaskets without any real checks done to the internals.
One thing we didn’t touch on is the points in the distributor. Unless those are brand new the best way to set them is using a dwell meter (if you can find one). Setting those will affect timing a bit too, so you want to make sure those are properly adjusted and then set the timing.
My dad rebuilt the motor in his 69 Cougar and got a “big” cam to give it that lumpy idle, but it never seemed to run quite right. I borrowed the car for a week or so and set the points and the timing and had it running really good. He was impressed, but disappointed because the lope from the cam was gone. Wondering if that’s not what your brother was trying to do as well.
Most of the time the advance timing isn’t really adjustable. You can change out the weights and springs to adjust it and there are kits to make the vacuum adjustable, but I’ve never messed with any of that myself.
Let me suggest a test. If you’ve done all this, just tell me to get lost. Crawl under the car with either a yellow/white crayon or some bright white or yellow hobby paint and small brush or even toothpick. Make two more marks at 20 and 40 degrees on the balancer (you may have to bump the starter to put the marks where you can reach). Plug the vacuum advance. From the top of the car, carefully watch the timing while revving the engine slowly to 3500 (this gives you quite the hair-dryer effect). All the parts-store replacement distributors have stock-type heavy centrifugal advance springs, so you may not see much shift in the advance direction. But this will establish what centrifugal advance contribution you’re getting in normal driving. More than usual, watch your fingers, yourself, and the timing light and its cables because of the fan. It’s tight in there.
I predict that, revving carefully while watching the timing light-lit balancer, you’ll see centrifugal advance through 3500 adds about 10-15 crank/balancer degrees to your initial. Stock centrifugal resistance springs won’t allow full centrifugal until 4000 or later, and by then it’s gotten pretty gale-like as well as more dangerous with the fan so close.
Ford made distributor rotors that gave 20, 24, 32, and 36 crank degrees (and those are only the ones I’ve seen over the years!). Any can turn up in a parts store rebuild (each rotor has two sides and is reversible, e.g., 20 with 32, etc), adding to the variations. On my 8.5:1, mild cam 302, I use 20 centrifugal advance from the internal rotor (with light springs so it’s all in by 2800-3000 rpm) and 14 to 16 initial. That gives me the 34 to 36 total I want, though sometimes I go a bit higher to 38-40 total.
Normal (what Ford gave 60s 289/302s) is more like 24 or 30 centrifugal, so, hence, the 6 initial being the nearly universal initial idle timing (vacuum disconnected) back in that period (24 to 30 cent. +6 initial = 30 to 36 possible total).
not even sure where he set the timing cause he kept messing with it. Also we never set the advanced timing which I couldn’t find a concrete answer on what that should be at. Also have heard the distributor makes a difference on what the timing should be. Not even sure what kind of distributor I have but it was a stock replacement most likely from an auto parts store post engine fire 10 years ago. Also the vacuum advance does not make a difference in engine noise when it is unplugged/capped/plugged even during running.