225/6 dist?

[te.ringer]

need some advice trying to fix /modify 225 dist 1973 with elec.ign engine idles great and engine is in good shape went through carb and rebuilt and all circuts work right,accel pump power,powervalve ect,unhooked egr valve.timming moves only about 10deg.found vacuum adv bad,but still cant get what I call normal advance curve,so I got a rebuilt/ new dist for it but the timming is still limited to about 20degs,if I remove the heavy spring it will advance 30 deg .can I replace the heavy spring with the lighter spring from the other dist without advancing to quickly and pinging,has champion n14yplugs stock holley carb.

[chirorod]

You can change the springs. This is usually a trial-and-error thing. If it doesn't ping, that's good. It's best to check the timing advance with a light that has an advance feature. Generally, the weaker spring(s) give a quicker advance rather than increasing the total advance. If it pings at wot you will have to retard the timing until there is no ping.
It sounds like the centrifugal advance on the old distributor is frozen. That is fairly easy fix

[te.ringer]

thanks for advise but both dist had a very heavy spring that wont let weights go to full adv not even with vice grips on both ends.I think its part of the emission system to reduce total engine timming to reduce co ect.,I remember replacing these dist.with points and getting better gas milage and power. back in the late 70's but now I just want to get rid of a hesistation off idle,the dist said 15deg total but could only get the weights to move 1/2 the way in grouve without removing the heavy spring.but dist is 2x 15=30deg in dist. right?

[chirorod]

double is right, because cam and distributor turn at 1/2 crank speed.
the older I get, the speedier I get cranky
they definitely want to keep the advance low for emissions purposes. Although, with the new stuff, that's all changed.