A lot depends on the length of the spring that you are swapping out, and the thickness of the wire it was made from. If you use a very light spring it can allow the advance to come out very fast, but also if the spring was not meant to be used in a longer slot it will eventually stretch and cause other problems later on (I have a few that are permanently like a stretched slinky that did not last long at 5000 rpm in a 15L slot....).

If the spring loses tension by being over extended and the other spring doesn't help moderate the advance the pins can move to the ends of the governor and slap off the end of the slot allowing the spring to gain some tension back but causing the timing to wobble +/-4 degrees (seen this in the 11-13R governor using light springs meant for the 9R or shorter governor, it works better replacing the light spring only and using the normal 9R long loop spring to moderate the final advance and keep the final advance in check).

If you don't anticipate doing any racing or going over 3500 rpm passing on the highway you should be OK. If the spring change does allow the full 22 degrees of mechanical advance then you will play with two vacuum advance pod choices to suit your driving style.

1) set static/initial timing to 8 BTDC, your spring choice gives an advance of 22 for a total timing at just above cruise rpm at 30...a vacuum pod from a reman/cardone distributor can give you 20 degrees of vacuum or you can try the Vc-208 for 22...(assumes you are not in the 10:1+ static compression range...) for total of 50-52 on the highway.

2) set static to 10-12 BTDC + 22 degrees of advance for 32-34 degrees of timing just above cruise rpm. Use a new VC-239 or a 184/185 for 17 degrees of vacc advance totaling 49-51 on the highway.

It's usually after you burn up 8 hours and 5 gallons of gas in the driveway changing springs and adjusting the fine points that a distributor machine becomes your buddy....



-D.Idiot

The slot in the arm that pushes the plate around should be long enough to allow 11 degrees rotation at the distributor, (22 at crank). Duster Idiot can give you the numbers for the stock parts that fit this description, but you can lengthen the slot you have with a dremel tool and a small cutoff disk until it does advance the correct amount. You can apply a vacuum to the pod while the car is running and watch the timing change. Some clever numbers guy here on the forum can likely tell you how long the slot must be to move the timing 22 degrees at the crank. Match that up with the mechanical advance slots you have and you will have a total of 50 if you set 10 initial. If you have an adjustable pot, you can set it so the v advance comes in at a range of vacuum readings that will match your car's specific needs.

Sorry for the redundancy here DI. I did not see your post while I was posting mine. DI's answer is more complete, and more detailed than mine is. But as you can see, we are saying essentially the same thing.

Sam

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Thanks fellas it's becoming a bit clearer now.
Gympie is a very hilly town and i was looking to get a bit more power down low , also the wagon is my daily driver , so a bit of around town and a bit of 100 km/h driving
I only go to the drags once or twice a year for a bit of fun and a laugh.
Sorry for jumping in on Nomad's thread but i figure the more info in one place the better.
The numbers on my pod are 8.5 R and 3755036 where it bolts onto the dizzy body.
I am also running a 3.23 diff.

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DRIVE IT,DON'T HIDE IT

I got my spring kit from bigslantsixfan. And I have read this entire thread at least twice. I know how to pull the dist and clean it up good. The part I don't understand is why I'd replace the OEM springs with something else. Because they are worn or to improve things is the answer likely. I guess I need to pull the dist and see what I got and post back?

BTW, this truck is running pretty nice. I'm trying to solve a dead spot just off idle.

The problem is you trust the factory to choose your curve based on the need to comply with emissions not mileage or improved power, the stock curve is typically a little "lazy" and having a slightly quicker curve that adds a little more timing while on the highway can pay a few more mpg and improve performance for such a little cost compared to other improvements.

3755036 is going to be a long slot distributor so what ever spring combo you put in either has to work with it, or be short enough to limit the weights from acheiving the full 30 degrees of advance that distributor can generate....

I'd use a slightly lighter spring in the full coil position, leave the long slot spring, use a wrench to move the slotted spring post to start the tension earlier-move it to the away from the main/center post (and limit the total advance), and keep your current vacc. pod for now.

-D.Idiot

Do you mean long slot governor ?
Because it is a NOS 3874714 dizzy from Old Car Parts and it came with a short slot R11 governor.

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DRIVE IT,DON'T HIDE IT