Help diagnosing miss

[COCHEV]

ok, picke up a used burb with a 454 with the "supposedly" rebuilt motor with a decent cam. anyways, it idles rough and misses. i was told it had a healthy cam. the miss seems consistant through out the rpm range. soooo, routine checkout shows this...

about 10-11" vac

dry comp test-
1- 100
3- 110
5- 110
7- 115
2- 110
4- 118
6- 110
8- 118

timing was very advanced 18-20ish (off the timing tab) but i've read 454s with larger cams run this way. i tryed retarding it to 12degrees and it ran worse- bogged and popped off idle

cap and rotor was well worn so it was replaced
plug wires were touching the headers so they were replaced as where the plugs. some plugs looked a little black, but not bad.

so could the one cyl. that is only at 100 cause it to run like it misses? could the coil be going bad? thanks

 

[SoCal'75]

did you do a 'wet' and 'dry' compression test? How about a leak down test? If the cam has lots of overlap then it will bleed off compression rapidly. Get the specs on the cam if you can and post them. Also remove the #1 spark plug and bring the piston up to TDC on compression stroke and check to see where the dizzy rotor is pointing. 20* initial advance is WAY tooo much for a BBC even w/ a healthy cam. You may even have some burnt valves. But one test at a time. Good luck
-Lance

 

[Thunder]

My gut feeling is cam. 454s like to eat cams. Espically if the cam was never broken in right