think i found cause of 2/3k rpm surging

[Walter_Middie]

Is one spring something that was done intentionally?

No - you should have 2 springs, one thick one and one thin. The thick one comes in at the higher RPM, and I bet that's the one you are missing.

Will full advance at 3700 hurt the engine?

As Kwikt 911 says, it may start to ping. This is not good for your engine, and can lead to catastrophic failure.

did not try it at 6000 rpm for 35 atdc. For some reason that scares the heck out of me to run it to that without a load.

This can be done easily - just start the car, go back to the engine and point the timing light at the pulley, then reach over with your free hand and briefly rev the engine. You will see the advance come in with RPM, then stop advancing as you mentioned.

You are shooting for 38 deg BTDC. If you only go to 35 with one spring, there is something wrong with your advance mechanism. I'd clean and lube it. You will be amazed at the added performance of a correctly advancing distributor

[47silver]

the engine was rebuilt in 1998, ported heads, 3.0 fuel distributor, bigger valves and many mods,, i called the engine builder Bob Farmer at Farmer's Automotive in Indiana. He said that he left the spring out on purpose because the engine needs the advance timing due to the upgrades he did. He also said that I should time it to 32 BDTC at 6000 for this particular engine.

So that is how I will set it up.