[DanEC]

Phil - why can you not get to 35 degrees? You just need to turn the distributor a little more to enter a little more initial advance in. 21 deg centrifugal (blue bushing) with 14 degrees of initial timing will give you 35 degrees. So I'm having trouble understanding your comment?

On the idle, the only way the distributor can cause a hanging throttle (provided it's not rusted or gunked up), is if the springs are so light, they won't pull the weights back to center until the engine speed falls to a point below where your idle speed is. Now, I've never had a MSD distributor so I'm assuming it doesn't have some other component or goofy thing that could cause that. If the advance springs are too light to pull the weights in at idle then you will need to go to the next heavier spring or see if there is someway to modify the light springs to shorten them and pull the weights back in a little more positively.

I've seen people disagree with this, but I insist on using an advance spring that is strong enough to keep the weights pulled in solidly at idle. I don't want the springs so weak that the weights are slipping in and out because that is jumping your timing around and making the idle speed inconsistent and unstable. I use the weakest spring that will still keep the weights pulled in solid at idle. You can test for this by watching your timing mark at idle - if it is jumping around a little, kill the engine and remove the cap and put rubber bands around the weights to keep them closed. Then check the timing again and if the timing mark is steady - you know the springs are too light to keep the advance weights closed at idle.

A Cobra is light and with a big engine, everyone wants to use light springs and a fast advance curve because you can. But, you may need to slow it down just a little to keep a solid idle. Also, if you have a lot of horsepower and torque, a little slower advance curve just might help a little to keep from completely blowing the tires at lower speed when accelerating. Just my opinion.