How much initial, distrib ,and total advance?

[Michael C Henry]

I have a mallory distributer centrifigal advance onlyI've just gotten the car running a little now the carbs are gone. .It appears that it only advances 10° to make 20° at crank. I currently have initial ignition set at 12°bftdc. My Mallory HyFireVI has a auto start retard which I have programed to 8°. So anything under 500rpm it starts at 4°bftdc and shifts to 12°bftdc. Then when it reves it advances to a total ignition advance of 32°bftdc.With the little bit it has run it seems OK .Time will tell if it creates a problem .Yoo much initial ? Not enough total ?
Thirty years ago I thought 38° bftdc total was the usual for an FE.
What are you running ?what have you done ?

[My427stang]

Lots of variables mostly based on cylinder pressure and load (car weight and gearing) but a good rule of thumb is 36-38 total and all in by 2700 rpm

With that, I'd try two things, bump your inital up to 15 and see if it pings, if it doesnt, close enough. With your start retard, it'll certainly still start fine.

If you dont like it at 15, then time to dig in and get more advance from the distributor. On my heavier car I like 14 initial, 38 total all in by 2500-ish

Once you get that total timing squared away, I'd look at the rate. You didnt mention how quick it comes in, and Mallory typically has a pitifully slow curve. With a Cobra, I cant imagine having the full advance at anything more than 2700 and probably more like 2400-2500 depending on your cam grind.

Every Mallory I have dialed in, has full advance at 3300+ and about 20 degrees centrifugal, so my guess is that you have a lot of snap left in that motor when you get a real timing curve in

Mallory builds them so any person can drop them in and not ping, anyone that wants them to run hard, has to work the curve. BTW MSD is JUST as bad, big heavy advance springs, they leave a lot of performance on the table until you recurve them

[Michael C Henry]

After some help from other club member I have determined that I have the older YL advance system. It isn't what they are currently using.They are using the YH or YT. and have an online four page instruction for that curve kit #29014.My Yl takes curve kit#29015 which I was unable to find online instructions for.I read under the other instruction sheet that distributer come with the abilitty to advance 24° and can be altered to go as high as 32° or low as 16°.
The other kit instruction showes several different curves in single and dual stages .I'll be asking more later. when my kit arrives.Do you think that the kit using the designated springs wiil accurately create the portrade curve or should I find someone with a distributer machine?
Do you remember the" Veri-Cam"Cam timing gear set? It went from advance to retard.1968-69That's another variable.
Thank you for responding

[cobra427mnsi]

My427stang

I am no expert by any means, but, if he can get a total timing of at least 32 degrees, how is it possible for him to get any pinging at 15 degrees initial timing. I thought timing was timing. The only reason not to have a big initial timing was it would be too hard on the starter. If the starter can turn the engine over with 20 degrees initial, then go with 20. You would just have to be careful with your total timing concerning pinging or detonation. From what I have read, set your initial timing using a vacuum guage. At idle (800-900 rpm), turn the distributor until you get the highest vacuum reading. That point will be your best initial timing. Now, if that is too high for your starter to turn over the engine, then back it off a little until the starter isn't stuggling too much.

I have a 63' co and it likes 18 degrees initial and 39 degrees total.

[SCOBRAC]

36-39 degrees total depending on fuel. We have 91 octane at the pump here and I won't go much beyond 36 total... 12 degrees initial...

[Michael C Henry]

I do not know how all the variables work but.Cosider a built 427 FE sideoiler +.020" over, aluminum heads ==11.5 to 1 compression ratio.Comp cams solid lifter cam 242 ° intake and 252° exhaust @.050" .598" lift , the cam came with 4° advance built in so its timed straight up, aluminum flywheel , 3.56 rear gears,2800 lb car sea level, 92 octane
If so much initial advance is a good thing.Why do manufactures reccamend numbers like 6° bftdc or so?

[My427stang]

cobra427mnsi - I guess I should have been more clear or seperated the two comments. Everything you said is correct, but there are tweaks you can do for driveability and piles of initial timing isnt always the right answer

1 - I dont think he has enough total timing, so easiest fix is to crank up initial. The problem is lots of initial on a low rpm / high load it may ping a smidge, like easing off a stop light, where a lower initial with a quick curve may not because its not yet in the curve


2- A better fix would be to build a curve that comes in quick enough to give him 38 or so all in by 2500-2700, with an initial a little lower. I like 14 or so max on the street with 38 total on an FE

A lower initial makes a cleaner idle, better smog (to a point), although I know it doesnt apply, when you sit at a light with 20+ initial, it can get smelly, combustion temperatures are lower and often you can mistake a low combustion temp for a mixture problem.

I am not sure if you guys do smog, and I cant imagine for any Cobra guy its a big deal, but they do burn cleaner at idle with the timing pulled back, cleaner sidepipes, fenders, (bumpers in my case with a Mustang). Notice I didnt say "run better" because advance is good, but looking at hydrocarbons and using a calibrated nose LOL I dont like to go above 15-ish on something that idles a lot

Matter of fact, I have seen a few, mine included, that I was considering changing the idle air bleeds in the Holley when in fact pulling 3 degrees initial out and putting it back in the centrifugal to quickly come in off idle got it to idle much less smelly

You can chase idle mixture, but a street motor likes some residual heat, and running reasonable initial (IMHO 10-14) gives enough performance and allows that heat to help at idle, where advancing it at initial lowers EGT to the point you'll get some stink

A race car is different, lock it at 38 and retard to start, but that motor would launch at 4500 and never drop below anyway

[My427stang]

Michael Henry - The automakers used short initial mostly for emissions, even when the rules were very basic.

In addition, the stock setup had up to 36 degrees of advance in the dist, and it came in slowly to be able to run on almost any kind of tar available. Take a stock 428 CJ and change the curve to what I mentioned above, and watch it jump, but odds are it wont pass smog like the stock setup would, even worse if you add more initial

We are running into this right now with a roller cammed 351C we are trying to pass smog for Nevada. I took the distributor, gave it a pile of centrifugal (28 degrees, but not in untill 4100) set initial to 6, and put the 195 thermostat in. We havent tested it yet but odds are it will pass. No changes to jetting. A solid roller 250@.050 single plane 351C

It'll run like $hit, but it'll pass because of the hi EGT finishing off any hydrocarbons, then we go back to a quick curve and moderate initial and all will be fun again.

[Michael C Henry]

I think I understood some of that.The Mallory #29015 advance curve change kit came today from Century Performance . I ordered it Tuesday and it arrived Thursday.The instruction sheet talks about a steady curve and a break out curve. I haven't figured one out yet. Performance is a consideration but it is a street driven car. It is supposed to go through emissions every other year. Granted it will never pass and I will have to go through the waiver prosces, but I have to show a little regard for tring to meet standards .Given the lightness of the car,aluminum heads ,cam, and single plane intake manifold, 11.5/1 comp ratio and 92 octane gasoline,and the peculiarities of an FE.How much initial how much total advance.Before I sent the carbs away I could get the car to idle around 600 rpm . I raised it to 700 just for oiling.Do I want a steady curve or a break out curve which advances quickly then slows down untill totaled is reached?This kit looks like it will do anything.

[My427stang]

I run the exact same setup, old style, and I like the linear in mine. I have done some break out curves, but mostly when its a very hot car with lots of initial and needs a very quick snap.

If I were you, break out that chart and figure out what you need to have everything in by 2500 is, basically you''ll figure it out in blocks of 1000, read it close then take a pencil and do the line chart it'll tell you which springs. I think its light green matched set? but thatsa guess, if you get stumped email me at My427stang@cox.net and I'll go look at the chart again, the chart is a little goofy until you get to know it

I'd go 14 initial, 24 in the dist all in by 2700 (2500 if you feel brave LOL)

Now, here is the kicker, when you go to smog it, recurve it again, its easy. In that case put it at 6 initial and swap the springs to come in late (>3000) it'll run crappy, but I bet it passes, then swap it back to the known good curve when you get home

[Michael C Henry]

I thought 12° initial was enough.I knew it was a little more involved than just crank it up and let it fly.I have been dinking with this car for the last two years and getting lots of flack about unused liescenses and insurance. If I decide on a curve, when emmissions comes around I'll probably turn the distributer backing evrything down.The waiver process works like this I go to the emmissions testing station and have the car tested .It of coarse fails.I have to go to an approved emmissions repairer. He will do whatever he can to get it into compliance. If he doesn't include adjusting the timing back I'll mention it.I'm only obligated to spend $150.The repairer fills out and signs a form .I drive the car back to the emmissions testing station .The car is tested ,it probably fails again. Maybe a little closer to compliance. The people at the testing station shuffel and coppy some papers.and I leave with a waiver to renew the tabs.Anything I do myself before the initial test doesn't go towards the waiver.
If I find a curve that works ,mind you the testing I'll be doing will probably be seat of the pants, I probably won't mess with it again. That is why I'm asking for suggestion based on experiance. What I just got from this exchange is for emmission testing purposes , just turning backwards the distributer should bring everything back down to help the emmissions levels.As I remember they have you bring the engine up to 2500 rpm (cruise speed) and all out wont be tested.
Starting at 600 to 700 rpm with 10° t0 14° initial and all out 38°.by 2500 to 2700 rpm looks like a short graft.I have to warm up the engine before getting on the thorttle The ruetine will probably be to plug in the electric oil heater for a few minutes ,start it up and pull the fast idle cam on where the choke used to be. open the garage doors ,open the gates to the alley and try to back the car into the alley, shutt the garage doors ,close the gates and It should be about ready to go. Shortly I'd be able to back the fast idel off and it would idle on the actual throttle stop at ( lets say ) 650 rpm. Ideling time is kept to mimimum as I've been told that the oiling around the cam and lifters sucks at low rpms.