98Z28MASS

iTrader: (6)

hey everyone, my buddy has 2001 z28. Hes got a 228/228 cam and full exhaust. We were recently driving it around town and having some fun, doing some 4000rpm-6000 rpm runs, and all of a sudden his engine started making some funny noises in the higher rpms. He shut it down immediatley and we had it towed back to his house. The car starts and oil pressure is fine, but it has a funny like almost sewing machine noise to it. We checked all the plugs and we are gonna do a compression test but the #7 cylinder plug was really dirty and reeked of gas. Since he didnt lose any oil pressur emy guess was a bent pushrod, as when he did the cam install he didnt put in hardened pushrods and since I wasnt there I was never aware of that fact till he told me today. We have the valve covers off and everything looks to be ok. We are gonna pull the pushrods in a little bit to see if any are bent but does anyone have any other suggestions? BTW the springs are comp 918's and its been full dyno tuned. Any suggestions/recommendations would be great!

oange ss

iTrader: (50)

take a look at the pushrods and a real good look at the valve srings, sometimes they will break but look ok at a glance

98Z28MASS

iTrader: (6)

Yea we were about to take everything apart but it got real dark real quick so we have to wait till tomorrow. It starts but is idling rough, and making some weird noises, and the compression test was fine but there is a misfire on the cylinder where the dirty/gas reeking plug came from and there is a significant lack in power when driving (when it first happened last night acceleration was awful). Like before oil pressure is fine and the car starts and we checked the coil packs and they are sparking so its not that, so we are gonna take a close look at the springs and pushrods tomorrow, but is there anything else it could be, such as a cam position sensor or something? We just want to try to track the problem down tomorrow and go from there, so any suggestions in addition to the springs and pushrods would be great. I know there are so many variables out there that it could be anything but any advice would be greatly appreciate. Thanks in advance!

oange ss

iTrader: (50)

may have just fouled a plug, change the one out from the bad cylinder, see if it helps

digitalsolo

iTrader: (24)

Check your rocker arms as well. If you lost the bearings from one, interesting noises will ensue.

ShevrolayZ28

iTrader: (4)

Lifter damage maybe.