I was setting the idle mixture on my Quadrajet the other day using the vacuum gauge method, and noticed the gauge fluttering very fast within a 2-3 in/hg range (15-18 in/hg). Sadly, I forget what exactly it means, but I do know the engine seems to miss at idle. I also noted that one primary tube was especially cold when checked with the infrared gun (213 degrees as compared to 500+ for most others). However, I pulled that plug (#8) and it looked normal. What can this mean? I am thinking that I may have burned an exhaust valve as the cat was quite plugged for about 400 miles of driving before I took care of it. Then again, it was missing before that too, and I seem to recall the gauge fluttering a year or two ago when I changed the cam and rockers. It seems to run quite strong off idle to the redline, but then again I don't know... Suggestions?
I will also add that the initial timing is set at 12 degrees ( vacuum advance disconnected) and total timing is in around 3k rpm at 36 degrees. The cam is mild and has a 114 degree LSA (Comp XE 262). Plug wires are new MSD 8.5 mm super conductor brand (changed at the time I did the tune up), it has a high output MSD module with a rev limiter, an MSD cap and rotor, and an Accel coil from the 90's. The plugs are recent enough that I did not change them ( NGK V power), but I pulled one and it looked good. I probably should re-gap all 8 to .44 though. I did find one vacuum leak today, but fixing it did nothing for the idle quality. I have been running 87 octane gas in it, but 93 makes no difference either except that I don't hear the little bit of WOT pinging I have with the 87 ( Just heard it today and will be retarding it another 2-3 degrees tomorrow). I run the 87 because it is cheaper and I have to deliver pizza with the car right now.
I will also add that the initial timing is set at 12 degrees ( vacuum advance disconnected) and total timing is in around 3k rpm at 36 degrees. The cam is mild and has a 114 degree LSA (Comp XE 262). Plug wires are new MSD 8.5 mm super conductor brand (changed at the time I did the tune up), it has a high output MSD module with a rev limiter, an MSD cap and rotor, and an Accel coil from the 90's. The plugs are recent enough that I did not change them ( NGK V power), but I pulled one and it looked good. I probably should re-gap all 8 to .44 though. I did find one vacuum leak today, but fixing it did nothing for the idle quality. I have been running 87 octane gas in it, but 93 makes no difference either except that I don't hear the little bit of WOT pinging I have with the 87 ( Just heard it today and will be retarding it another 2-3 degrees tomorrow). I run the 87 because it is cheaper and I have to deliver pizza with the car right now.
