Camaro_87

i just bout a 87 z28 with a high performance 355 engine while driving it home i noticed from takeoff when i really give it gas the car shakes alot and i can't even get the tries to spin the previous owner said i have to use the really good gas in it but instaed i used something else could this cause it or is there something else wrong?? the he also said it never shaked from takeoff with him. what could it be??

ZEEYAA

It may be, because I think all our v-8 require at least 91 oct. What kind of crap gas did you put in it? Did you notice any spark knock? And what do you mean the car shakes?

Camaro_87

i didn't really put crap gas in it but it wasn't as good as the gas im supposed to use. and spark knock what is that? and by shaking i mean when sitting in the car and from a dead stop i give it gas the car itself shakes not really hesistates but it vibrates alot and like i can't even do a burnout. bu twhat im gonna do is finish the gas thats in there completly , it;s almost on empty now and put the right gas in it and go from there.

3.492rs

sounds like wheel hop

Camaro_87

wheel hop?? what is that never heard that before.

mnorton

Sounds like the engine is missing on two or three of cylinders to me....

Camaro_87

other then the shaking form takeoff ir runs good we were doing around 120 on the highway for about an hour straight with no problems

ScottieB

check for a messed up spark plug wire. When is the last time you did a full tuneup? This sounds just like when my car was "missing"... one of the wires had a cut/hole/whatever you want to call in it, and it was sparking on a piece of metal. move your wires around while the car is on, and see if the idle changes. if it does, get a $20 spark plug wire set and replace them... But I would do a full tune-up if you haven't in a while.

Camaro_87

Alright thanks for all the advice im going to try some things tommorow when i get home from work and ill let you guys know.

ChevyGuy87

Instead of moving the plug wires around while the engine is running, get a spray bottle of water and spray down the wires and distributor cap while it's running. If you're arcing anywhere you'll be able to see the sparks. I prefer this way, as I'm not a huge fan of being shocked by the ignition system.

Check a couple of your spark plugs, too. Or better yet, spend the $10 and put some new ones in.

Camaro_87

hey sorry i didn't reply sooner busy week at work any way i took the car out for a quick ride considering i don't hav eplates or insurance yet for it but i notice that the car doesn't only shake from takeoff but if im sitting in the car in park and i rev the engine the whole car shakes and vibrates like just sitting in the drivers seat and reving the engine you can feel the seat vibrate.

hellfire

Sounds to me like you need to rebuild the carb. Floats are probably your problem.

Sonix

iTrader: (1)

your motor mounts aren't great any more. How "high performance" is this mystery engine? That'll make a car shake more then your average civic.
You need 91 octane at least. Run that until you find the problem and fix it, then you can try stepping down to cheaper gas. I don't think you'll get to though.

Make sure all cylinders are firing for sure. Maybe even pull the valve covers, and idle the car and make sure all your valves are opening. That's my latest malady..

Camaro_87

i don't think it's the carb i have a brand new holley high rise carb on it. im not to sure how high performance this engine is but th eguy i bought it from said it was high performance that he put alot of money into that engine. a local performance shop custom built the engine for my car he said if i can ill post some pics but i tried and can't find out how to post them can someone tell me how?

Camaro_87

Ok heres a link to a picture of the engine in my car
http://www.cardomain.com/ride/2413349/1

Camaro_87

ok today i put some 94 octane gas in it and took it for a drive it ran alot smoother and didn't vibrate as much but it still has some vibration but not as bad im gonna try changing the plugs and wires and go from there.

Sonix

iTrader: (1)

i'd call up the previous owner and have a nice heart to heart about what's in that motor... You can't just fill up your car with gas, and drive it around as if it's a factory motor, when it's a custom built motor. Who knows, it might have 12:1 compression, a solid cam, etc etc. There are things you should know about that motor....

Dizturbed One

^thats what i was thinking

you better be careful

i think you are causing detonation, and that's what the vibrating is... STOP getting on it, play with your timing a bit, and put good gas in it.