'95 Z28 383 engine issues, help
'95 Z28 383 engine issues, help My buddies 383 seems to be acting up. It runs like PURE ***! At idle it runs very rough, has this exhaust leak sound coming from the #7 area, we put new header gaskets on a few days ago, still there. When you give it some gas it stumbles, pops, and somtimes stalls. It's running kind of rich we know, so we need to tune it but it's something else. We checked the rockers, they are fine, I checked the pushrods on the #7 cylinder, they are fine, no broken springs, etc. When you drive it, it runs bad under 3k rpms, stumbles, surges, etc. When you get on it and it goes up around 4k rpm+ it runs like a bat out of hell, but when you let off the gas and decel, it backfires, pops, etc.
The plugs are brand new, wires aren't burnt, etc. On the scanner it's misfiring and getting 13 degrees of knock. We have narrowed it down to an optispark gone bad, but not 100% sure, so we are replacing that tomorrow to see if it fixes it.
What do you all think it sounds like? Here's a brief list of the parts....
383ci
Comp Cams 306 cam
AFR 190 heads
Hydra Rev kit
Crane 1.6 rockers
Chromoly Pushrods
Hooker long tubes
3" True Duals with Magnaflows
Canton oil pan
Manley rods
J&E Pistons
10.5:1 compression
Street Twin
Meizere electric water pump
MSD 6A
and many more.
Any help would be greatly appreciated!
The plugs are brand new, wires aren't burnt, etc. On the scanner it's misfiring and getting 13 degrees of knock. We have narrowed it down to an optispark gone bad, but not 100% sure, so we are replacing that tomorrow to see if it fixes it.
What do you all think it sounds like? Here's a brief list of the parts....
383ci
Comp Cams 306 cam
AFR 190 heads
Hydra Rev kit
Crane 1.6 rockers
Chromoly Pushrods
Hooker long tubes
3" True Duals with Magnaflows
Canton oil pan
Manley rods
J&E Pistons
10.5:1 compression
Street Twin
Meizere electric water pump
MSD 6A
and many more.
Any help would be greatly appreciated!
T3h Mighty LT1 PWNSSS JUUU!!!!! 
What are you doing with an LT1 Scott?
BTW, sounds like an opti and possibly a burnt wire.
What kind of gaskets are you using with the Hookers? Have you made sure the flange is infact flat, any deviation and it will blow a normal gasket out, a copper one might seal better.
Oh, and Scott, what cam did you go with in the Nuclear Pumpkin?
What are you doing with an LT1 Scott?
BTW, sounds like an opti and possibly a burnt wire.
What kind of gaskets are you using with the Hookers? Have you made sure the flange is infact flat, any deviation and it will blow a normal gasket out, a copper one might seal better.
Oh, and Scott, what cam did you go with in the Nuclear Pumpkin?
Hey Rob, yeah this LT1 will own me It's a buddy of mines, I pretty much talked him into every part of this car so I feel guilty it doesn't run right.
I will recheck the wires tomorrow at the time I change the opti, hopefully it runs right after that.
I went with the LG G5X3 cam for my car, runs pretty good
It's a buddy of mines, I pretty much talked him into every part of this car so I feel guilty it doesn't run right.I will recheck the wires tomorrow at the time I change the opti, hopefully it runs right after that.
I went with the LG G5X3 cam for my car, runs pretty good
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Staging Lane
Joined: Feb 2003
Posts: 91
Likes: 0
From: Mesa, Az
Who put the cam in the car? Are we certain that the dots on the crank and cam gears were lined up? Just how stumbly is the car? Any clickity clackity type noises? Try the opti and see if that fixes the car. Have you checked the fuel pressure? Did you do the dark test to look for misses? BTW, you will need bigger injectors with that setup when the car is running right. Where is this car located? I am pretty good at fixing these things. I live on Sossaman and Guadalupe and could check it out this weekend if you have not figured it out.
A friend of mine put the motor together (Wayne Bauer), and the engine was redone at HiPower. Everything was installed correctly, it's been running right for about a year, just over the past month it's crapping out. Not really any clackity clack, just an exhaust leak sound (Identical) around #7, but not a real leak. The injectors don't seem to be maxed out right now, the car only put down 401rwhp and 382 rwtq before the MSD, fuel pump and true duals, the old exhaust was CRAP and was killing it, I don't doubt it to be at 425+rwhp now.
We are located in Mesa/Gilbert, he lives around Alma School/Elliot, I'm Val Vista/Warner area. I will be doing the opti at GearHead Garage tomorrow morning, if you are in the area stop by. If it's still f'd after this, you are more than welcome to listen to it.
I did do the dark/night test, no arcing, etc. Fuel pressure was perfect. We're stumped, it has to be the opti or else it may just accidently catch fire
We are located in Mesa/Gilbert, he lives around Alma School/Elliot, I'm Val Vista/Warner area. I will be doing the opti at GearHead Garage tomorrow morning, if you are in the area stop by. If it's still f'd after this, you are more than welcome to listen to it.
I did do the dark/night test, no arcing, etc. Fuel pressure was perfect. We're stumped, it has to be the opti or else it may just accidently catch fire
You might want to get a tech 2 and take a look at you 02 sensor mine went out and my car did the same thing your is doing minus the exhaust leak. Just a thought. good luck with your motor. Hope it works out.
I do want to check the O2 out as well, I plan to try a different one tomorrow, maybe swap the passenger side out with the driver and see if it helps or changes things. A friend that scanned it showed the driver side O2 to be out of wack/showing rich, which we know #7 seems to be running. I hate cars 
Unmetered air is what came to my mind too. Check that and the opti/plug wires. Just curious....why the hydra-rev kit? Those things kill valvetrains, and the 306 hardly needs anything like it.
Fixed the 383 today, stupid phuqing opti, turns out one of the plug wires he replaced wasn't a correct one, the end that goes into the opti was too large, so it didn't seal around the hole. Looks like moister got in and corroded the #4 plug wire and inside of the opti. I replaced the opti and the plug wire, fired that bitch up and it runs like a mother phuqer, just murders the tires and PULLS HARD!!!!
It has an exhaust leak at the collectors, and that may be hurting a little since the O2's are after the collector and it may be pulling air in and screwing up the computer, he is getting new gaskets for them and installing them tomorrow, then the car will be ready to retune and dyno, hoping for at least 420+rwhp now.
All I got to say is phuq LT1's! I'm so glad I own an LS1 car, that opti wasn't "hard" to replace, just time consuming, removing the balancer, crank pulley, water pump, radiator fans, etc, etc. Ugh, my hands and arms are beat down, but it was worth it, car runs strong and is faster than my car easily!
As for the Hydra rev kit, never heard it kills valvetrains either, we got it because my friend who we got the motor from had it on there. It will help prevent the lifter from lifting, bending a pushrod and bending valves. He revs the car to 7k rpm, so we need any extra protection we can, when the Nitrous goes on (200 shot), no need to chance things. Also we are planning to add a MUCH bigger cam shortly.
It has an exhaust leak at the collectors, and that may be hurting a little since the O2's are after the collector and it may be pulling air in and screwing up the computer, he is getting new gaskets for them and installing them tomorrow, then the car will be ready to retune and dyno, hoping for at least 420+rwhp now.
All I got to say is phuq LT1's! I'm so glad I own an LS1 car, that opti wasn't "hard" to replace, just time consuming, removing the balancer, crank pulley, water pump, radiator fans, etc, etc. Ugh, my hands and arms are beat down, but it was worth it, car runs strong and is faster than my car easily!
As for the Hydra rev kit, never heard it kills valvetrains either, we got it because my friend who we got the motor from had it on there. It will help prevent the lifter from lifting, bending a pushrod and bending valves. He revs the car to 7k rpm, so we need any extra protection we can, when the Nitrous goes on (200 shot), no need to chance things. Also we are planning to add a MUCH bigger cam shortly.
Congrats Scott!! That thing sounds like a beast!! I've almost completely gotten rid of the damn opticrap. I've got t3h p0w3rful LS1 coils now! I have gotten as good as being able to get the front end off the car in about an hour now, just to play with the stupid opti.
Thanks dude, we were thinking of going the coil pack route, but we needed the car to be fixed right away, and we weren't sure how that coil pack route works out, etc. Sounds like you need to come help us with any LT1 issues form now on, hehe, you're quick
