Thread: RRC 3.5efi distributors

Got an update guys . Ive run both these dizzies now in my motor .
The one with 11 stamped on the weights I set at 14deg advance static idle allowing 36deg total
The one with 14 stamped on the weights I set at 8deg advance static idle allowing 36deg total .
All these settings were checked with adjustable timing gun .
VERDICT . THE ONE STAMPED 11 LEAVES THE OTHER FOR DEAD IN PERFORMANCE ! There is no comparison give me the 11 any day !
Anyone got any dizzies lying around to check stamped values on theirs ?

That is probably because the vacuum advance modules give the same vacuum advance at part throttle and you are running 6 degrees more vacuum at light throttle by running at 14degrees static at normal running revs.

The centrifugal advance only fully advances over 4000RPM.

This is what most interceptors do ie add quite a bit of electronic advance to replace vacuum advance as these engines seem to be able to take lots more vacuum advance.
Just to elaborate a bit further . The centrifugal advance of the dizzys differs by only 3 degrees and they advance about 1 degree per 1000RPM. So at 2000RPM the difference is maybe 1/4 degree . BUT you have advanced the 11 degree dizzy by 6 degrees. So what I am trying to say is that the REASON you have better performance is vacuum advance not centrifugal.
Regards Philip A

Phillip,

I kind of get the feeling that you experienced the following while writting that reply!

To quote Austin Powers .... "Oh no I've made myself go cross-eyed"

Phillip can you try to elaborate ?

The way im seeing it is that the timing curves are ending the same at 36deg and even reving past 3000 both dizzys arent advancing any further .
Im not sure of all in by 4000 im seeing both these all in by 3000 .
Both dizzies mechanical advance seem to begin around 1200 1400 with the vac disconnected .
Were you trying to say more initial timing and not more vac advance .
The performance difference is remarkable between the two and it think its all related to the extra initial (or static) timing .

I agree.
I was just saying that seeing the vac advances are almost certainly the same, the big difference you feel is because you have advanced the 11deg dizzy by 6 degrees over the 14 degree one, and that the vacuum advance will be advancing the timing much more than centrifugal at most used engine speeds and loads.
Theoretically you can gain lots by just replacing the vac advance with a Haltech which given lots of time on a dyno , you could get a more optimum curve. Although IMHO no operators are willing to spend time at part throttle to tailor the advance to an optimum.
That is what car makers spend millions on and why modern cars with high compressions, knock sensors, and 3D timing maps go so much better than old ones.
Regards Philip A