questions about timing

[frankym]

I had some issues around timing and welcome any suggestions. I recently replaced my exhaust header gaskets because I was convinced that the sound I was hearing under load was an exhaust leak. I discovered that the sound I was hearing was engine knock. I took the car to a couple of shops and the first shop adjusted the timing a bit by seemingly randomly turning the disributor without a light or any other guideposts. The knock continued and I then took it to another shop that had more familiarity with old school carburetor motors. He found that the total timing advance was set at around 55 degrees. He adjusted the car for a total advance of around 39 degrees. The mechanic said he likes to tune cars for a 3,000 RPM total advance of around 36 - 40 degrees. The knock dissapated a bit but I marked a line on the base of the distributor and turned it clockwise (at the mechanics suggestion) to retard the timing just a hair. The ping/knock was still apparent and the only noticible difference is that the car now cranks over a little more slowly when it's hot. Ironically, this is the first time the cranking has been slow when the motor is hot (suggesting that the previous setting was not so advanced after all).
My question is, what is the appropriate range of total advance for a crate 351 windosr with cast iron heads and if I wanted to retard just a little, should I be turning clockwise or couterclockwise?

Any help would be most appreciated.

Thanks
FM

[wtm442]

An engine that cranks over too slowly usually has too much advance.

An engine that pings/knocks usually has too much advance and/or gas which is too low in octane.

I time mine at about 34 degrees at 3000 RPM. But I ALWAYS use a timing light

[frankym]

Clockwise or counterclockwise to retard?

[white rose]

Take the cap off and look at the rotor rotation, it should turn counterclockwise in which case turn the distributor counterclockwise to retard. Best to use a timing light before you start to get an idea of the timing before you move the distributor.

[trularin]

First and formost, knocking is BAD!!!!! It is not a good idea to drive around while it is knocking.

Second, get a timing light.

Third, everyone has an opinion about timing, engines and the universe. If it is knocking at 39 total advanced, you may want to try premium gas, octane booster and a little lead additive. Then again, you could, using a timing light, back off the timing even more. Too little will cause backfiring and really sh!tty drivablility.

fourth, if you drive around with a constant knock, you could pop a hole in a piston.

Hope this helps.

[Bob In Ct]

55 degrees sounds like way too much to me. I always thought about 36 full advance was the max one would want to go. Correct me if I'm incorrect.

Bob

[jarendall]

what type ignition system are you running, also are you running aluminum heads, jacking the timing around can cause excessive heat build up, which is not good for aluminum, pinging usely comes from to low octane as everyone has mentioned, never run low octane gas in a high performance engine, I am running a Mallory system with the Hyfire module, all you have to set on it is the base timing, the module controls all advance timing, my distributor, has a magnetic pickup and nothing else in it, do you have a vacuum advance

[frankym]

thanks for the helpful suggestions. I need to retard the total advance a few degrees at a time and test. Since this is the first time I've experienced hard starting when hot, I don't know how advanced I was after all. The claim from my mechanic was that it was set at 55 degrees and is now at 39. I will turn the housing counterclockwise a degree or 2 and then drive it and see if I can rid the pinging sound. I have a duraspark ignition system and the standard FMS crate package with iron heads, not sure if the distributor is vacuum advanced or otherwise but this is all very helpful. I am also running 93 octane with the 104 boost bottle. With all of your help, I think I can adjust the timing in small increments and rid the world of the ping.

Frank

[CSX 4027]

Timing is a science and is critical. Anyone that does the twist without a light is a criminal. First, before you did a thing you should have removed all your spark plugs, numbered them and had an expert read them. Go to a spark plug reading website, maybe champion has pics and see what detonation does. It will actually eat away at the top of the pistons and could blow a hole. The plugs will show the story. Then, put a new set of plugs in and set total advance all in by 2500 rpm's at 34 and see what the motor does via the plugs. Then adjust up or down 2 points at a time and check the plugs again. If you cruise at 60-65 at 2500-2800 at least you will not be running retarded pinging the hell out of the motor. It does however sound like the damage has already been done though sorry to say.

[frankym]

I wanted to thank everyone for their help. From the helpful suggestions here and from a great article in Ford Muscle, I was able to make a few tweeks and complete eliminated the pre-ignition detonation issue. I was able to back off the initial timing by a few degrees and lowered my total advance at 3,000 to around 34 degrees. I was at 39-40 and that was too much. I'm now in a much more comfortable set point. I was hoping to find the vacuum advance diaphram to retard just a little on the advance under load scenario before the RPMs kick in. I was unable to locate the vacuum advance and am now left wondering if the car just has the mechanical timing advance from the springs and weights. Anyone know where I might find the diaphram? The only vacuum diaphram was located on the carb for the secondaries. The car runs perfectly and I appreciate all of the help along the way.


Below is the link that was very helpful to the issue.


http://www.fordmuscle.com/archives/2...ng/index.shtml

[Bob In Ct]

In the 60s it was on the distributor. Just follow the vacuum line if you have one.

Bob

[frankym]

Bob that was my first try looking at the distributor but I was only able to find electrical wires including some in sheathing. Not sure where to look for the diaphram. Perhaps it simply doesn't have a vaccum advance and just the mechanical is all I've got.

[wtm442]

The vacuum advance "canister" is located on the outside of the distributor. See pic - mine is a little rusty and needs polish or paint

The vacuum hose is just out of the picture, but its there!

[frankym]

I have and MSD billett distributor and I definitely do not have that canister on the outside of the cap like the one featured in your picture.

[wtm442]

You probably do not have any vacuum advance, unless there ios a separate vacuum unit wired to the distributor. (doubt it).

Vacuum advance results in much improved MPG while cruisin'.

[jarendall]

you may have to set the advance timing using a special tool, it may come as a kit, go on line and check with MSD on how to set the advance timing on your distributor, if your distributor has the springs and weights, then it is a mechanical advance distributor

[rlearp]

Originally Posted by frankym

I have and MSD billett distributor and I definitely do not have that canister on the outside of the cap like the one featured in your picture.

I have the same one, it is a mechanical advance dizzy. Adjust mechanical advance as mentioned with the springs and weights. You don't need a vacuum system on it anyhow, it'll run very well as is provided your initial timing is set correctly and you don't have too much total advance, as well as getting it all in by 2500 RPM or so. Sounds like you have it licked.

Ron

[lnfletcher]

Try these sites
http://dnr.louisiana.gov/sec/execdiv...p/auto/h/h.htm
and
http://www.sweptline.com/tech/engine2.html