A few months back I bought a 94 Z with a blown headgasket. Got it all back together and got it running and it runs real rough. I have adjusted the rockers multiple times, and it still runs rough. I will try to get a video. When I turn on the A/C, it runs REAL rough and every now and then a extremely loud pop comes out the exhaust. Anyone ever heard of this problem? Also, it just suddenly started dropping oil pressure out of nowhere. Oil pressure was excellent, and then suddenly started dropping and is down to 10 lbs at warm idle. Think any of this could be related? I will try to get a vid, sorry if none of this made sense, just kinda throwin some stuff out there seeing if anyone else has experienced this.

 

I highly dout this is your problem, but when we ajusted my rockers we forgot to hook up the vaccume line to the brake booster. As for the oil, mine always ran at about 10lbs warm at idle.

 

Yeah, that is hooked back up lol. Never disconnected it when I did the rockers.

 

When you replaced the headgasket, did you bring the heads to a machine shop, or just bolt them back on?

Have you checked the oil for any signs of water? How is the water level in the radiator?

Thomas.

 

Make sure the plug wires are in the correct order. What rpm are you seeing 10psi?

 

10 may not be too low. The more important issue is what is it as speed increases? 55-65 psi or about 10 psi per every 1,000 rpm is the norm.

Backfiring out the exhaust can be caused by many things. Since that is the only clue you have at this time, it may be prudent to continue on the quest for that problem as it may be the cause of the erratic running.

Back firing can be caused by many things. Valves not adjusted correctly and staying open or not closing on time. As well as other items in the valve train keeping the valve open too long. Wrong length or bent push rods. Etc...

Cylinder not firing correctly as in not at the proper time. Swapped wires can do it. Burned valve causing lower than normal compression can do it. So to can the wrong mixture cause the problem. Stuck open injector or clogged injector can do it.

There is one explanation that could account for all your problems. Damage to the bottom end from coolant getting into the oil (stoopalini was asking for that reason). The coolant could have wiped out a main bearing or more accounting for what (may) be low oil pressure. Running erratic and backfiring could also be accountable from coolant contamination damage.

When you did the heads, did you run all the pistons to BDC and check the condition of the cylinders?

At this time your most prudent first step would be to check compression. If any one cylinder compared to the others seems low, it would then be a good idea to do a leak down test.