ftwZ28guy

Hopefully I posted this in the right forum. If not feel free to move it. I did a plug change on my 2001 Z28 the other day since it was running pretty rough at idle. I replaced the bosch platinums that were in the motor when I bought it 6 months ago from the dealer with some TR55's. The wires are MSD's but not sure how old they are. To make a long story short all of the plugs looked normal for the most part except for the #7 plug, the outside threads were soaked in oil as well as the porcelain tip inside the plug itself had a light coat of oil on it. I plan on running a compression check on that cylinder to try and rule out blowby from the rings but thought I would probe here for some more ideas as to what might cause this.

Oh and the car still has a miss at idle

Thanks for your help

jay_99z

iTrader: (5)

Hate to tell you this but......I'd guess ring issue. My buddies did the same thing. Compression checked and 30psi on that cylinder. Took the head off and found a nice groove worn on the wall from a trashed ring.

He also had oil and smoke blowing out the oil cap when it was running.

Good luck.

calongo_SS

iTrader: (7)

you're probably not going to like what you find.

DaddySS

Unless that cylinder is really low the plug should fire and if the rings are bad you should see blow by coming out the oil cap and smoke out the tailpipe. If not, you probably have an ignition problem with that cylinder.

ftwZ28guy

Thanks for the replies guys, I'll probably tear into it here in a couple of days. I'm not sure if it's smoking out the pipes or not, I'll have to get someone to follow me and see what it does under load. what's a good psi to look for when doing a compression test on these motors? is it the same as other SBC or is it diff.?

ddelallata

iTrader: (2)

I noticed that on the threads on some of my spark plugs the other day then I realized it was just excess anti seize that I applied previously...but you have oil on the ceramic? Probably something else.

jay_99z

iTrader: (5)

I'm not sure on stock. We were getting 190-210 (aftermarket heads) on all but 5 and 7. They were like 30 and 60.

Basically check the others and compare. You should def see a differance if you have a problem with rings or valve.