turning the distributor for initial timing

[Harry L.]

My initial timing mark is 18 degress above the the O mark on the A side. I have to lower it. Which direction will I have to rotate the distributor. thanks DUTCH, THIS IS ON A 427 390 HP

[Timothy B.]

Re: turning the distributor for initial timing

Harry,

You will need to slightly retard timing. Turn the distributor clockwise toward firewall.

[Duke W.]

Re: turning the distributor for initial timing

My initial timing mark is 18 degress above the the O mark on the A side. I have to lower it. Which direction will I have to rotate the distributor. thanks DUTCH, THIS IS ON A 427 390 HP

Did you disconnect and plug the VAC signal line. There was a thread on 427/390 initial timing a couple of days ago.

Duke

[Stuart F.]

Re: turning the distributor for initial timing

Good point Duke. I first thought; what? 18 degrees initial?! Heck, I can't hardly see my mark when the vacuum is connected and wouldn't even have reason to when setting my initial timing.

Stu Fox

[Harry L.]

Re: turning the distributor for initial timing

Yes, I did disconnect and plug the vac line. thanks for the reply. DUTCH

[Duke W.]

Re: turning the distributor for initial timing

You also want to make sure the centrifugal advance has not started. With the OE setup the timing should be set below 600, but how do you know yours is still OE?

Test to see where the centrifugal starts to make sure. Also make sure the VAC actually works.

If the initial truely is 18 and the spark advance map is OE I can't imagine that you would not be experiencing signficant detonation. I suspect there are other issues that need attention.

The OE initial timing spec is 4-10, and the centrifugal adds 30 at 5000.

A lot of these 30-50 year old cars have screwed up ignition systems. Some have been modified. Some have dirty, corroded, sticky centrifugal advance mechanisms. Some have or jammed or dead VACs.

Before anyone attempts to "set the timing", you should test that the entire spark advance map works and what it is - OE or modified. Initial timing is just a small part of the equation and you need to know the entire map before you mess with the initial timing.

All this has been discussed many times and all the specs are in your CSM and AMA specs.

Duke

[Harry L.]

Re: turning the distributor for initial timing

The person that owned my 427, 390hp before me modified the car with a competion cam, 030 bore ,and I put on a 780 cfm holley carb because, I needed more air. I am in the process of giving this car a tune up. DUTCH

[Michael W.]

Re: turning the distributor for initial timing

Some have dirty, corroded, sticky centrifugal advance mechanisms. Some have or jammed or dead VACs.

Guilty as charged. I found this week purely by accident that my vac. canister was 'dead' due to a perforated diaphragm. No idea how many years it had been like that but the replacement unit sure makes one heck of a difference.

[Duke W.]

Re: turning the distributor for initial timing

If everyone did a thorough inspection of their ignition system including taking the spark advance map data, checking dist. shaft axial and lateral play, and checking spark plug wire resistance, I bet about half would find a deficiency.

It's not that hard to do and has been discussed here many times. The distributor and other ignition system components are the most overlooked systems on these old cars.

Most guys think that replacing the points, cap, and, rotor consitute a thorough tuneup, but at some point over the decades, lack of maintenance and inspection of other critical ignition system components is going to cause problems.

If the spark isn't delivered at the proper instant to all eight cylinders for the effectively infinite number of speed and load conditions, the engine will not perform at maximum efficiency or achieve design performance.

To the OP, since your engine has been significantly modified the original spark advance map is likely not suitable. (You would have received better responses if you revealed this data in your original post.) How to set it up, especially when a higher overlap cam is installed has been discussed here at length, multiple times

Duke

[Harry L.]

Re: turning the distributor for initial timing

Well it is all over, my car is running better than ever before. DUKE, If you would have told me that numbers were not as important as the actual grabbing a hold of the distributor, and with movement one way or the other,I could control my cars destiny. I did not need any scale to achieve the best performance. It can mostly be done with your EARS. DUTCH