Stock timing curve on a slant 6

[myraley]

Hi folks. I am trying to understand distributor curves, and according to my manual, my 1967 slant 6 engine should have a initial timing of 5 BTDC, a mechanical advance total up to 25 BTDC, and a vacuum advance up to 15, for a total of 45 BTDC max with all three combined. That seems consistent with the information I have found here on the site and around the internet, although I know some people go with higher initial timing and less mechanical. They all still seem to come out totalling around 45 BTDC max in the end.

What I was wondering is if my curve would work well if it looks like this. This is assuming That I use the factory 5 BTDC initial timing.

500 rpm = 5 BTDC initial, no mechanical yet
1500 rpm = 15 BTDC (initial and mech)
2000 rpm = 20 BTDC (initial and mech)
2500 rpm = 25 BTDC (initial and mech)
3000 rpm = 30 BTDC (initial and mech)
3500 rpm = still at 30 because it tops out without vacuum at 30 BTDC.

Does that make sense? Its nice and clean, but it doesnt match the curve in the manual, which advances timing very quickly from 750 rpm to about 2200 rpm and then levels out. It still stops at 30 BTDC with the initial and the mechanical and without the vacuum advance though. Is anyone else running stock initial timing or am I the only one? Does anyone have their timing curve mapped out and could post it for comparison?
Thanks!

 

[myraley]

Anybody know what their timing curve is? What are you setting the timing at initially? 5 like my service manual says? Or something different?

 

[Mrmopartech]

With springs kits and some grinding of the weight limiters you want to get about 2-4 degrees of timing every 250rpm,that,s taking in initial timing as well,so you can accelerate the motor as fast as possible.If the motor is using 45 of timing,it does show a low compression motor,as a high compression motor will handle 32-38 degrees,s of total timing at about 15 initial timing.The faster you can make the timing come in with out pre ignition/pinging or hard starting,the better you are,as you can get to full power faster.mrmopartech

 

[805moparkid]

well i know my pre 70's dizzy had about 15* of timing @ about 2K and then another 10* at about 4K...

thats how i lost my top rings... cuz i was running 15int for around 30 total(or so i thought!!)

but yea my slant is all in at 800 or so... so i have a timing retard in effect and then as soon as it starts its at what ever * i want solid...

as for your dizzy it sounds like a electronic dizzy as it has the quick curve in it... like most of us like...