I've been playing with recurving my distributor, and this is for informational uses.............. (work in progress)
Car Specs:
1964 Plymouth Valiant V100 4-dr
14750 miles
Engine - 225 stock
Carb - stock
Transmission - stock 904
Rear End - 2.93
Tires 195/70R14
Testing:
a)87 Costco gas
b)vacuum disconnected and plugged
c)Consists(ed) of measuring the stock curve with dialback timing light
(for consistency all timing events referenced back to 0 with timing light
(idle at 0)), I didn't use the timing marks (i.e. I'll get consistent errors) to
determine the curve, then I set initial timing.
d)distributor locked up (removed springs) and then timing advanced in 2.5degree intervals looking for ping and noting rpm if it happens.
e)determine 'ideal curve' from b&c......
f)try to match curve....... measure
g) test run anyway to see if things get better (or does it still ping when I expect it to) goto f)
h) I did use the brake to either slow down acceleration or hold speed
Notes:
1) Stock curve will occasionally ping when set to 2.5 degrees BTDC
2) I had to get to 17.5 degrees timing (all rpms) before there was any hint of a ping.
3) Looks like up to 15 degrees Idle should be safe
4) The in by 3000rpm rule doesn't seem to apply.
5) After centrifugal is done, I'll attack vacuum
6) And if you want to know, the stock torque converter stalls at 1750...
Picture:
1) Purple Curve is stock
2) Pink is what I think the ideal curve should be (will modify if testing indicates otherwise)
3) Yellow is where I'm currently at.... and it does ping where the yellow curve is above the ideal curve....
Looks like I need some different springs..... stiffer on the primary to flatten that part out, and lighter on the secondary to let it rise faster.
BTW, the inflection point in the curve is determent by how far the weights move before hitting the secondary spring..
)
