Just purchased 76 from auction, has 123,000 on it. Engine has been rebuilt but to what degree have no idea. Had to replace harmonic balancer so checked timing chain/ gears. it has a double gear/chain with little to no wear, chains have about 1/4 slack/play in them. Replaced distributer cap rotor plugs and wires. I have read through all the post, great info. I set my inital timing at 8 and all in at 36 at about 3,000 rpm. Drove it and runs reasonable, first question when I hook vacum back up timming goes to 36 at idle. number on vacuum can is 23. I cant get the Idle to stay steady it will stay at 1100 for while then drop to 700 then hunts back and forth.(have ben told probly vacuum leak so loking for that) I have a scondary problem that may be related and is reason idle set so high. when i put in drive(obviously an auto) the Idle drops 4 to 500 rpm, if i set idle to 7 or 800 rpm then in drive(or reverse) it drops to 2 or 300 and I beleive would eventually die. I allways put into nuetral when at stop sign. No matter what the idle is set at in park when put in drive the drive train is imeadietly put under load, as if the by pass or what ever its called in the trans when the brake is on is not working right. Any sugestions on where to go from here ? Is the distrubuter just wore out or would bad vac can cause these problems.