Thanks for the info everyone. Here is my tale of woe. I recently completed a complete 100% restoration on my 70' Challenger T/A that I purchased new back in 1971. The car had been of the road since 1988 and stored in my garage. No price was spared in the restoration with the exception of the windshield wiper motor! Several service dealers in my city recommended this machine shop to me for the engine rebuild. I met and spoke with the owner/operator about all of my past experiences, and previous problems, with this 340. He seemed to know what he was talking about, plus he was recommended as "knowing his stuff". Talked to several other shops as well and got estimates from two others. Both other shops were substantially cheaper than the person that was recommended to me. I didn't want it cheap, I wanted it right. I gave him the go ahead to do the engine. I wanted him to rebuild the engine, assemble the engine and then put it on a stand and run it, and tune it. Upon complettion of the engine, my body rebuilder picked up the engine and installed it in the car. When the car was finally completed, my car rebuilder dropped the car off to me in an enclosed trailer. We backed the car out of the trailer and I drove it around the block. The car seem to run fine, but I noticed it had a slight tapping sound. I called the engine rebuilder and voiced my concerns and his excuse was that it was "these new HP cams" and that it would quiet down after some miles. Long story short? It never did. I drove the car for 23 miles in total. As the car revved up to shift (automatic, not standard) the tapping/clicking, became much more noticable. I called him again. He advised me to have my garage look at it as the timing may have been set too high. His interpretation of the noise was "pinging" and not tapping or clicking.
made an appointment with my service mechanic (third party now)that i deal with with my fleet service to have this noise checked. Dropped the car off. As soon as i arrived home i had a call from my fleet service mechanic who then told me that the motor was going to have to come out of it because one of the crank berings was gone. Needless to say, i was shocked. My service guy had taken the car out on the paved sideroad, stepped on it and, bang, the tap became a knock.
Called the engine rebuilder and told himn to get over and see this thing. He did, and all agreed the engine had to come out. Problem was serious, especially after an $8,800.00 rebuild with 23 total miles!! I had my service mechanic take the engine out of the car and take it over to the rebuilder. Two days later I get a call from him and he tells me #7 bearing failed and it failed because of these possible reasons:
1) I didn't use high octane fuel and the bering was caused by ignition(of course high Octane pup gas was used!)
2) Engine must have over heated (it didn't. it ran very cool with the gauge showing always to the far left of the middle)
3) My gauge or sending unit must be faulty ( it wasn't. Just put another send ing unit it the engine and it reads the same. Entire cooling system, hoses, rad, water pump, stat were all new.)
4) timing must have been too far advanced and destroyed the engine due to pre-ignition (it was set at 8 degrees!!)and he set it!
Rad and engine must have pugged up because there was black residue in the rad and engine ( the was some, but the new installer said it was from the debris from the engine rebuild. He said he baked the engine to clean it)

Needless to say, he wasnt going to give me any warranty on the engine. After some pressure form myself and my service mechanic he said he would cover it all, including the re and re. When the engine was done, i was away on holidays whn i had a call from my service mechanic who told me that the rebuilder mwouldn't release the engine to him and that he wanted to be paid for the parts and now wasn't going to cover the re and re. To get the engine back i told him to pay him for the crank bearings and that I would cover him for the re and re. My service mechanic has now put the engine back in the car and I got it back yesterday. Appearantly the engine rebulder didnt even thake the crank out of the engine, he just put bearings on the crank and put it back together. Again, long story short? Another $1300.00 and a very bad experience. All of the above brings me to my vaccuum and timing questions. This idiot that rebuilt my engine has blamed pre-ignition for this Bering letting go in my motor. We dont think that is the case at all. When my service mechanic asked for the old berings he regfused to give them to him. I dont want to go through this again. Your thoughts on the above? How should this engine be set? What should the timing be? Do I need to recurve the dist and how does one do that? Is premuim pump fuel fine?
Thanks to all before hand
JIM