What is your timing curve?

[1 Wild R/T]

So, something to look out for/be aware of when going with light springs for a quicker advance curve.... It was pretty common with 80's-90's MP distributors that when idling you were already pulling in mechanical advance... One of the issues this would create is idling is pulling in timing, as the timing advances engine RPM's increase.. As engine RPM's increase, more timing comes in... More RPM's brings in still more timing... So you can go from idling at 750 in gear, slip the trans into neutral and very quickly the idle climbs to 1800-2000 RPM's... Or another scenario the engine is idling in neutral at a steady 800 RPM's but there's 3-4 degrees of timing advance already in the distributor... Your drop the car in gear & the RPM's drop 75-100 RPM's.. The timing falls out... Engine stalls... Not knowing why the engine stalled o compensate you try turning the idle up 75-100 RPM's... Guess what the timing/idle is gonna do?

You need enough spring on the advance weights to keep timing solidly on the base till around 1000 RPM's.. What I do is when modifying the slots (Which I weld) I weld up the inside of the slots not the outside like most folks do... Now light springs are under some tension so they don't advance quite so soon....

 

[Kern Dog]

That is an interesting idea....welding up the inside of the slots.
In 2006, I took this car to a guy in Sacramento that had a dyno. He set the advance curve while he was there and rejetted the carburetor. There are tabs inside the distributor that the springs attach to. He bent them outward to tighten up the slop in the springs.

Regarding the 50 degrees....No, there was no detonation but there also was no load.
I had the vacuum advance hose connected for all three combinations. Maybe I should have disconnected it but I run ported vacuum, not manifold vacuum. With no load on the engine, I figured the VA wouldn't have been in play. I know that books, service manuals and magazine writers have stated that the VA should be disconnected during testing but in every car I've tested, the line adds no timing when under no load.
I could plug the line on this distributor and retest just to see if there is any difference but I do know that at a 1000 rpm idle, pulling the line doesn't change the rpms.

 

[lewtot184]

The 14 slot on my fbo plates is actually 8.5 degrees.

 

[DeltaV]

It appears I’ve hit my limit for starting new topics here.

Don't sweat it.

Timing is a new topic? Did you try the search function?




Just don't start a what's it worth thread.

 

[moparedtn]

It appears I’ve hit my limit for starting new topics here....

...today.

 

[MMorgan]

Speaking of incoming insults… here they come I’m sure…. But! I am sold on the progression ignition distributor. A main reason is exactly what’s been talked about in this thread. Lots of variations in different engines. To have a standard. I haven’t decided if I’m going to leave it in, or use it as a tool to discover the best set up and try and duplicate that on an analog distributor. They are amazing!

 

[Don Gould]

So you have a 3800-5000 stall convertor, the engine won't lock the convertor until it hits that number so why do you have the timing come all in at 2000? Weak springs and a radical idle will cause the timing to bounce around.
4sp? your probably never going to drop that clutch under 3000RPM
If you think there's movement in the distributor check the slot in the intermediate drive, I just peen the drive tab a little so it fits snugly.

 

[33 IMP]

I basically don't have one.
I'm using a direct connection iron tach drive distributor that has a very aggressive curve, from Mopar.
I set timing total where I want it (no vacuum advance on this race distributor)
and the curve acts like a start retard. Total timing is in at a 1200rpm idle in gear.

 

[Don Gould]

I basically don't have one.
I'm using a direct connection iron tach drive distributor that has a very aggressive curve, from Mopar.
I set timing total where I want it (no vacuum advance on this race distributor)
and the curve acts like a start retard. Total timing is in at a 1200rpm idle in gear.

Is this a all out race engine?

 

[33 IMP]

Is this a all out race engine?

Nope, just a warm 440 in a bracket car, occasionally street driven. Low elevens at 122. I can get it to idle at 800, just much easier to drive with some more idle vacuum/rpm. My nine second car doesn't have an "all out race engine", I can't afford one, lol.