new distributor?

[Anonymous]

The other day I decided to check the system over, which included the timing. I notice that when I set my initial timing at 10 degrees, the engine runs much smoother at idle when the transmission is in Drive with my foot on the brake.. I have a C4 automatic..

When I set the timing to 14 degrees, there is way too much vibration. So I split the difference set it at 12 degrees, which is a reasonable place to be. What surprised me was that when I took off the vacuum line to the distributor it made no difference when I observed the timing mark w/ timing light. I plug the line, unplug the line. No difference. A friend tells me that it's almost certainly a bad vacuum advance unit.

My engine is a 200/6 from 1967. I have a Pertronix II electronic ignition and a Pertronix flamethrower coil. My friend who helps me with this stuff says that I should ditch my stock distributor and get a performance one. Okay... but which one would be compatible with my Pertronix II ignition?
Would it really make that much of a difference?

 

[JackFish]

When I set the timing to 14 degrees, there is way too much vibration. So I split the difference set it at 12 degrees, which is a reasonable place to be.

This is true for me also, way smoother at 10*, which is, by the way, factory spec for the '78 factory non-california 200.
There should be no reason for advance vacuum at idle, no?

 

[CZLN6]

Howdy back:

The factory setting for a '67 200 with a C4 trans is 12 BTDC. Initial setting should be done with the vacuum line disconnected and plugged. If, when you try 14 degrees, the idle speed goes up, you should reset the idles to about 600 rpm before assessing. If idle speed goes up with more initial advance you may also need to retune the low speed air screw to get it to smooth out. All of this assumes that your ignition system is in good condition.

Your Autolite 1100 carb with a Spark Control Valve and your Load-a-Matic distributor are designed to work together. IF you plan to change/upgrade one, you should also change the other to a compatible unit.

There are good stickies at the top of this forum to help you better understand your carbs SCV and your Load-a-Matic distributor.

If your engine does not change speed when you disconnect the vacuum line to the distributor, you most likely have a blown SCV or plugged vacuum line. If the engine acts like it has a vacuum leak when the line is disconnected then you likely have a blown vacuum cannister. A rebuild kit for a '67 200 will have a new SCV.

The advantage of a later ('68 and later) is that you gain a centrifugal advance as well as a vacuum advance system. This is an improvement in both performance and economy over the '67 and earlier Load-a-Matic ignition. This point type distributor may be able to utilize your PetroniX II unit. In the early '70s Ford introduced its 1st pointless electronic ignition called Dura Spark. It was farther refined in the mid 70's with the Dura Spark II system. It includes the distributor, the coil, the module, wiring harness and Spark plug wires.

The downside is that you will need to upgrade to a '68 or '69 Autolite 1100 with no SCV. These carbs will be a reduction in performance because they have a cfm of 150 as compared to the '67 at 185. The best option is to find an Autolite 1101 from a 1969 Mustang 250 which is rated at 215 and has no SCV, is compatible with the later distributor and pretty much a bolt-on.

So the first step is to figure out what's up with what you've got.

"Would it really make that much difference?" If you can get your current system to work as designed, Probably not. If you have already optimized your current ignition system by opening up the plug gap and tuning carb and timing for best performance. What you would gain with a '68 point type distributor you'd lose by having to go to a smaller cfm carb.

Upgrading to a DS II and an Autolite 1101 would make a nice difference.

Hope that helps you. Keep us posted.

Adios, David

 

[cfmustang]

Maybe I am way off, but timing itself should not affect the idle in drive with the break engaged.

My guess is that your idle speed is set so high that bumping up the timing from 10 to 14 degrees is raising the rpms at idle just enough that you are starting to hit the stall speed of you torque converter.

What RPM are you at when idling?

The test would be to lower your idle speed at 14 degrees and see if it still happens. Does it happen in netural?

As for the vacuum advance, isn't ported vacuum about zero at idle? I believe it is manifold vacuum that is high at idle...

 

[Anonymous]

Funny that, because I'm also in the process of ordering the Holley 5200 and Stovebolt adapter today.

Thanks for the clarification!

 

[jahearne]

You can't get any better in a performance distributor than a DUI.

http://cquesttechnologies.com/fspp/products.asp?cat=73

Add a two barrel and a header and you got a great set up that's reliable too.

 

[mugsy]

As far as I know the LOM carbs and regular ones do not send vacuum to the dizzy at idle. If they do the throttle plate is open too much and the idle should be too high.

To check if the vac advance is broken first start the car and make sure it is warm and up to temp. Disconnect the vac line at the carb but leave it connected to the dizzy. Apply vacuum to the advance unit at idle (buy a hand pump or use your mouth). If the idle increases and/or use a timing light to see if the timing changes (increases). No change means the vac unit is bad.

Second thing to check is what kind of vac is being developed by the carb. Again make sure the engine is up to temp. Put a vac gauage on the line connected to the carb and disconnected at the dizzy. Move the throttle by hand and see what the readings are. My experience is with a factory set-up there should not be any vacuum at idle. The vac should increase as the throttle is opened and start to go back down the closer the carb is to WOT.

 

[jahearne]

That's exactly what I did to test mine. I used a vacuum pump, but first I mapped out the vacuum reading from the carb at different rpms and noted where the engine had problems. Port vacuum is zero at idle and manifold is high usually between 16 - 21. You should have seen the timing jump when I hooked up my old lom dizzy to manifold vacuum.