Methods of setting timing

[Anonymous]

I set my timing using the "advance it til it pings then retard it a bit" method. It caused my 66 I6 Convertible to have hard starts. Although the driveability was great. I reset the timing with a light to about 12-14 degrees BTDC. Now it starts easy, but acceleration is not a strong. I also checked timing via a vacuum gage take off on the log intake.

What is the concensus on preferred method to set timing?

Ear...

Light...

Vacuum gage...

 

[Anonymous]

Just what you did, increase it until it pings or starts to kick back, then tune carb for best vacuum. My timing is at 13, I can go higher without pinging and more power but the starter kicks back, static compression 9.4.1.. Are you running the DS2? You should make sure you are getting full mechanical and maybe experiment with manifold vacuum.

 

[MustangSix]

"advance til it pings then back off" may be too much advance even if it doesn't ping. The idea is to light the mixture so that you achieve maximum cylinder pressure after TDC.

Light it too soon and you have the pressure tying to push the cylinder the wrong way. That's why it's hard to start. Light it too late and you don't get the full energy content of the burning mix.

The timing requirement changes constantly with load and engine speed. that's the job of the advance mechanism.

 

[Anonymous]

I have a Pertonix magnetic pick up inside the dizzy and an MSD-6A on the driver's side fender wall.
Both have helped with drivability tremendously.
Cheers,
Steve-O

 

[Lazy JW]

From your description of the symptoms I would suspect that the advance mechanism isn't functioning properly. The fact that it can be advanced enough to get good performance tells me that the engine wants to run, and the fact that when too far advanced it kicks back tell me that it isn't getting enough advance. Both conditions can be corrected if the advance comes in properly.
Joe

 

[Anonymous]

From your description of the symptoms I would suspect that the advance mechanism isn't functioning properly. The fact that it can be advanced enough to get good performance tells me that the engine wants to run, and the fact that when too far advanced it kicks back tell me that it isn't getting enough advance. Both conditions can be corrected if the advance comes in properly.
Joe

Do you mean that the the vacuum advance may not be working?

I'll do a mechanical advance check with the vac line off (rev engine and watch for advnace on timing marks) (if I have centrifugal advance) and also bump up the idle to about 1200 - 1500 rpm then put on and take off the vac line to see if that is operating as well. I guess I should see my initial timing + mechanical advance max out at about 2500. Total advance will include vacuum advance and may be tough for me to actually see, but I think I can hear if that is working.

Thanks for the tip.
Steve-O

 

[Anonymous]

that whole "total advance and how to set it" is confusing to me

I get initial advance...and the THEORY behind total....but checking/setting confuses me

 

[CobraSix]

It's really hard to check total advance with a vacuum advance set up.

Initial: That is the timing the dizzy is initially set to. In theory, your timing can NOT go below this value since it is where all the timing springs have completely tight and against the stopper posts, and if using a ported vacuum system, at 600-800 RPM, there is no vacuum

Centrifugal: This uses a set of springs and weights that spin further outward as the dizzy goes faster (engine RPM increases). This has the effect of advancing the timing in a somewhat linear fashion as the RPM goes up until a certain point (usually tops at 3000 or so RPM). The rate of change can be adjusted by changing springs.

Vacuum Advance: This uses the vacuum to further adjust the timing by advancing or retarding total timing based on engine loading. the rate of change can be adjusted by changing or adjusting the vacuum diaphragm.

Total = Initial + centrifugal +- Vacuum(though, IIRC, vacuum for a centrifigul dizzy has no effect on total timing).

It is really easy to set the initial + centrifugal for total timing. You'll usually need either a dial back timing light or a longer timing marks. You set initial...run the engine up to 3000-3500 RPM and check timing again.

FOr vacuum, you'll usually need a vacuum pump to see how far the vacuum is changing the timing.

Please correct me if I'm wrong...I always get the vacuum stuff mixed up.

Slade

 

[Anonymous]

Slade,
Good stuff.
I checked my initial timing...right about 14 BTDC.
I checked if mechanical was working. Saw the timing advance right off the bat when I revved the engine. No vaccum lines attached to carb or dizzy.
Then I tried to check the vac advance alone. What I did was use a vac gage on the dizzy take off port on the carb. What I got was only a max of about 5" vacuum when I revved the engine up.

My question...if anyone has done this or would be willing to try on their set up is...what peak vacuum should the carb be pulling on the dizzy when you rev the engine from idle to about 2500-3000 rpm?

cheers,
Steve-O

 

[wsa111]

Setting timing is different for every engine combination out there. If you have a stock engine with a stock cam you can probably use 28 degrees centrifigul advance with about 10 degrees initial, all depends on your compression.
If you have an engine with higher compression & a camshaft with degrees in the 214 @ .050 you can put 24 degrees crankshaft in the distributor with lighter advance springs to bring the total centrifugal in by 2500-3000 rpms & try 12 to 14 degrees initial advance. The total initial advance plus centrifigul should be in the 36-38 degree area. This can be checked with a timing light @ 4500-5000 rpms to verify the correct total with the vacuum advance disconnected. The vacuum advance is an educated guess,experience or trial & error method to get maximum fuel ecomomy & part throttle driveability.
You really need a sun distributor machine to properly tailor a proper advance curve. The best thing you can do if you don't understand what i'm saying is use a professional distributor shop to do your advance curve depending on your engine combination.
If you want to custom tailor a curve yourself, pull the distributor cam off the top shaft by spreading the snap ring the remove the breaker plate to expose the centrifigul advance mechanism. the ford distributors are marked in degrees. the degrees are in distributor degrees which is 1/2 of crankshaft degrees. this piece with the advance removed can then be removed & rotated 180 degrees to obtain that limit of advance stamped on the cam-avance mechanism. I have modified many a distributor by using e dremel cutter to add advance to this piece & have brazed up the slot to limit the total mechanical advance. As i said before if i'm over your head don't hesitate to send your distributor with your engine combinations & have them tailor the proper advance curve for your own application.
Steer clear if a distributor shop that wants to set your curve to stock ford specs unless your engine is stock. you need a professional tuner to do the job right.
Sorry to be so long winded but every combination is totally different. good luck william
The best advice i can give you is find someone older than 50 to get the job done right.

 

[Lazy JW]

Steve-o,
If you are using the correct ported vacuum hookup at the carb you won't have any vacuum at idle, and it will be difficult to get an accurate reading with no load on the engine. For test purposes I have attached a Tee fitting in the vavuum line and then ran a vacuum guage into the cab so I could read what was happening going down the road. Wsa111 has good advice, you can get pretty close by test driving.
Joe

 

[Anonymous]

Good idea. I had forgotten about there not being much load at idle and/or revved sitting still...thus not much vacuum. I think I'll T it like you said and run a spare vacuum line with the gage to the passenger compartment and see what I get.
Definitely was the correct port on the carb.
Thanks again.

Steve-O

 

[mugsy]

Steve-O,

Well it sounds like to me that the carb is for the old "Load-O-Matic" dizzy, which is vac advance only. Can you take a picture of the other side of the carb? It looks like the same carb that I had, which if you still have the carb tag, is a later '70s replacement carb. GIve us the codes ont he tag if it is there. Plus the load-o-matics needed only 5 " Hg to work and the carbs were set up for this level of vacuum. Regretfully, for Fordz, the carb and the dizzy have to match. The dizzy might not be getting enough vac advance to run right.

Mugsy

 

[Anonymous]

the best advice i can give you is find someone older than 50 to get the job done right.

lmao

thats what I said...time for the pro-feshunals

 

[Anonymous]

Steve-O,

Well it sounds like to me that the carb is for the old "Load-O-Matic" dizzy, which is vac advance only. Can you take a picture of the other side of the carb? It looks like the same carb that I had, which if you still have the carb tag, is a later '70s replacement carb. GIve us the codes ont he tag if it is there. Plus the load-o-matics needed only 5 " Hg to work and the carbs were set up for this level of vacuum. Regretfully, for Fordz, the carb and the dizzy have to match. The dizzy might not be getting enough vac advance to run right.

Mugsy

Hope I didn't confuse you with my post....my current carb is an Aurolite 1100...Newly reworked from Pony Carbs. The dizzy is mechanical and vac advance.

Advice has been great. Hurrican Ivan is causing rain/wind here now so will check vac underway tomorriw if wx holds up.
Will op check tomorrow.
Cheers,
Steve-O