Benefits of using a start retard and pinning the distributor?

[Yellow Truck]

Percy, my neighbour and engine building/carb tuning buddy, suggested I consider replacing the MDS 6AL box with a Pertronix Digital  HP box and pinning the distributor at max timing.

On the one hand having an easier start is nice, I don't run the vacuum retard now and timing is set at 26 initial and 34 total. Getting initial down under 20 would probably help the starter last, although it doesn't seem to struggle - but I do occasionally hear it kick back during cranking.

My question is, what is the benefit of running the engine at total (i.e. max) timing all the time except on start up? Percy did say that I may get few benefits other than easier starting (and the claimed better spark characteristics of the Petronix box) since I already run fairly big initial timing.

[GerryP]

The engineers who work in the powertrain divisions of all the manufacturers are complete idiots.  I mean profoundly stupid.  They -and I mean all of them- went through the trouble of using centrifugal advance and vacuum advance mechanisms for nearly every vehicle that rolled off the assembly line.  And, the accountants...don't even get me started on them, those imbeciles!  The they could have saved the company money by not paying for a bunch of useless parts in the distributor.  Think of how much they could have saved if the ditched the centrifugal and vacuum advance.  Maybe not a lot for an individual car, but over millions of cars,  why, you could buy a country for what they wasted.

Seriously, this is a bit tongue-in-cheek, so take it for what it's worth.  If you are building a dedicated drag or track car, then by all means, lock out the distributor.  If you're not doing that, then there are clear advantages to using both centrifugal and vacuum advance.  I will say this on vacuum advance, though;  The higher your static compression the less value there is in vacuum advance.  Once you're over 11:1, you don't need vacuum advance.

There is one other scenario where you would lock out the distributor and that is where a computer is controlling all timing events.

[pbf777]

...............................and pinning the distributor at max timing.

............................... - but I do occasionally hear it kick back during cranking.

My question is, what is the benefit of running the engine at total (i.e. max) timing all the time except on start up?

     Having the distributor timing advance function "locked-out" is fine for engines that when in use remain at an R.P.M. that would/should be experiencing full advance anyway; as if only this reduces the possibility of experiencing component or function  failure of such system in competition.   But in the more dynamic R.P.M. operating range required in most "street" operation if this is practiced, one may experience greater difficulties in the starter motor operation (if not retarded as you mentioned), and particularly in manual transmission applications in the transitional throttle applications implemented during shifting and at lower to mid range R.P.M's at moderate to heavy loads experience detonation ("engine knock") which is best avoided.       

     Scott.

[428 GALAXIE]

I would assume spark curve would be in the box?

With start retard.??

Why not.

[mikeelikee]

Bingo!!   

I will say this on vacuum advance, though;  The higher your static compression the less value there is in vacuum advance.

[Falcon67]

Every "street/strip" engine I use here has locked timing.  The Mallory box has a 10 degree retard, so cranking advance is 26 on the 302 and 28 on the 351C.  The 351C runs 10.5:1 compression.  I only use PMGR starters and have zero starting issues.  Driving at the track in the lanes I'll start it 4~5 times or more when at operating temp.  Carbs are easier to tune and set, car is more responsive, timing easy to set - just one number.  If you run a performance converter with an automatic, who needs a "timing curve" because you'll be past the "all in by 2500" range before you get 30' out.  The dragster engine has no retard, is set at 26, 11.8:1 and starts easy. 

[pbf777]

     C'mon,.......... for "period correct" function: one would place a spacer under the distributor hold-down bolt so as when the bolt is tightened it would lock the hold-down fork rigidly, retaining the distributor body vertically, but permit rotation (don't  forget the grease); then establish "stops", such as weld beads to the distributors' locating rim, shaped/ground to act against the hold-down fork, permitting the desired timing sums of "START" & "RUN"; then fabricate a bracket to the two screw holes for the vacuum dashpot (removed if equipped & don't forget to lock-down the breaker plate if applicable), and cable stay bracket to the intake manifold bolt at the front, for attachment of a push/pull choke cable routed to the interior dash board.  There needs to be sufficient "drag" on the cable or the use of the "ratchet" type, to resist the rotational reaction in operation of the distributor body, and perhaps an added tension spring in the linkage may be required to dampen this effect. 

     This is how we dun-it before the "BOX" come along.     

     Scott.

[Yellow Truck]

I would assume spark curve would be in the box?

With start retard.??

Why not.

The Petronix box has start retard, but it doesn't provide a computer controlled spark curve. I am surprised at that, but it relates to the utility of having initial vs full timing. I haven't read much on the purpose of a timing curve, only the problems of having a bad one. If the purpose is better fuel economy or such, then I don't care and would go with a pinned distributor and a start retard. If it is to make starting easier, ditto.

If delaying full timing makes the engine run better at idle to 2,500 RPM, that would make me reluctant to eliminate it. For what it is worth, if I had it to do over I would not give a dime to MDS. Aside from the multiple failures with the "ready to run" distributor, their customer support was like dealing with inmates in a lunatic asylum. I would be strongly inclined to run the Petronix box and even if I didn't pin the distributor I'd add a small start retard to get start timing down around 18 degrees. The starter is handling 26 degrees but if I had it I'd use the start retard to make it easier on the original Ford starter.

[Jim Comet]

I have been running locked out timing on my high 10 second Comet with the Pertronix digital HP and and very happy with it. I also wish the timing curve was programmable. The 2 step and start retard along with the rev limiters all have worked flawlessly through my 1st year. Jim

[Yellow Truck]

I have been running locked out timing on my high 10 second Comet with the Pertronix digital HP and and very happy with it. I also wish the timing curve was programmable. The 2 step and start retard along with the rev limiters all have worked flawlessly through my 1st year. Jim

I was puzzled that it didn't offer a programmable timing curve, but it may be because there is really no value if you have start retard. I don't really have enough experience with timing to really understand how it affects performance. What I do know is that at idle my engine ran better at 27 degrees than it did at 18 or 20, but it also didn't run any worse at idle all the way up to 40 degrees.

Hopefully one of the usual suspects with lots of experience and insight can tell us why initial timing is used. Percy, my neighbour and tuning buddy has a lot of experience building sprint cars, and they all run locked in timing. Now they are all push started, and run pretty much flat out all the time, so initial timing is irrelevant.

[Jim Comet]

I should have added that I have a 5000 stall converter, so the motor flashes right past the rpm range where the timing curve takes place. Jim

[BattlestarGalactic]

Basically as long as it doesn't knock/ping under load in lower RPM you can run as much timing as it will take.  That is the only drawback to locked timing.  In a daily driver, you can get into trouble if you lug it too much at a low rpm and it rattles.

[Falcon67]

Very true - as with any configuration parameter, it's completely application and total system dependent.  Big Galaxy, 390, 11" converter, 3.23 gear - ya, you'd likely benefit from timing control.   Light car, 10" performance converter, 3.70 up gear - maybe not. 

FWIW - I haven't had any issues with MSD parts.  I use their pickups instead of Ford type if I run a Duraspark type distributor.  The ignition in the door car is a Mallory 685 with a lot of built in functions.  I went with that one because it was cheaper and had more functionality (retards, window switching, dial back for nitrous applications, etc) than an MSD 6 or 7 with all the extra stuff hung on it.  Dragster runs a 7AL-2 and a MSD crank trigger - no issues with either.

[Falcon67]

Here - something else to consider

http://4secondsflat.com/Daytona-Sensors%20Main.htm

http://4secondsflat.com/CD1-MSD-Crane%20Comparison.htm

[Jim Comet]

The last thing I will add is, if you call Pertronix you may be able to get one of their Digital Mobile HP units like I have. The benefit to this is all functions are controlled with your smart phone. It also reads out a live tach and voltage readings. It was $300 bucks which I thought was a good deal for the features it has. Jim