So earlier I had rebuilt my distributor on a 65 327/350 and used the Lars Method to time it. Only trouble was that it kept coming in and maxing out way to early (750 in/1400 max). So I figured that I needed to do a new set of springs. Got the spring kit and put in the recommended silver and black spring - Same result. Put in a silver and gold spring - better but not much (850 in/ 1450 max). Put in two golds (the stiffest ones) and still not much better. So looking at them I thought I needed a shorter and stiffer spring. A lot like the springs in my HEI set up on our 70 Elky. So I dug out my HEI parts and had a stiff and medium HEI spring which are shorter and I believe stiffer. Put them in and now my curve is 950 in and 2250 max. So if you are having the same issues, I would recommend looking at the HEI springs as a replacement for what we are getting in our "new" kits.

 

What tach are you using eng speed. The car one or a separate one?

Tom

 

how are you testing ? do you have a sun machine ?

 

What do I use for RPM? The digital tach on my timing light BUT that readout corresponds really close with an old school dwell/tach that I had hooked up to the coil. Of course the ultimate test is that 720 on my light shows as 700 on my car's tach (joke - but it does)

I don't have a machine. Wish I did cause that would be a LOT more accurate. How am I testing? I have a set back timing light (before anyone tells me that they aren't accurate - don't. I also have a damper that shows 360 degrees which is what I use to set the actual timing numbers cause I have had two set back lights that changed readings at will). I use the set back function so that the 0 degree mark sits right at the timing mark. When I start to up the RPM it makes it really easy to see when the timing starts to change. So I turn the idle screw up slowly and when the timing 0 degree mark moves, I look at the RPM on the light. Same trick on the upper end. I know my upper timing is 36 degrees without vacuum. So I run the engine up above where it's all in, set the light so that it reads 0 degrees and then run the engine RPM up again slowly till I see the 0 degree mark line up and look at the RPM again.

Know it's not a Sun machine set up but it works and with the HEI springs in, it made a huge difference in the way the car runs.

Geek

G

 

I have a digital setback light as well. It has a tach button on the back. You can switch from the timing display to tach and back. Pretty cool. It also has a 2/4 cycle button. I kept bumping the 2/4 cycle button and it screws up the tach display. Way off! Not to imply you didn't set the dist up right but may be worth a check if you have a 2/4 cycle selection.

Tom

 

Ahh I see the genesis of your question. Nope. Wish that were the deal but it's on the 4 cycle setting. I got bit pretty bad with one of my earlier set back lights and that's what set me in to having the degree'd damper. My new light has the RPM always showing on the right and the left side gets changed to whatever I select (dwell/volts/degrees).

 

OK good. Mine was driving me crazy until I figured out what I was doing.

Tom

 

Its no SUN machine but that method (which I use) is quite adequate. You can easily 'spot check' the timing at various intervals and extrapolate the curve from a 'dial back' timing light.