Whenever i am accelerating in low gears my engine makes a rattling noise, its hard to explain what it sound like but i would say it sounded like something knocking against something else. I know something isnt loose because it only does it in low gears. Also, when i turn my engine off it starts to shake and refuses to turn off. My car is an 84 z28, please help!

 

check motor mounts? my 83 did it.. only in first though.. turned out to be a tranny mount

 

Sounds like your ignition timing is too far advanced and the idle is set too high...

The rattling sound is "spark knock" or "pinging", caused by the fuel being ignited too early during the compresion stroke, and consequently exploding instead of burning smoothly. The other problem is "run-on", which you can usually cure by backing down the idle speed.

------------------
"So many Mustangs, so little time..."

 

how long has this been happening? check the timing asap and use gas w/ a little more octane. if you let detonation (spark knock, or pinging) go on for too long it will kill your motor...break the rings and maybe put some holes in a piston or 2


------------------
350, Comp 262, Edelbrock Performer intake 600 cfm carb and exhaust, headers

 

If it sounds more "solid" than detonation, like something definitely hitting something else, you might have a bearing on the way out.

------------------
1984 Silver Z28, decked 383 cid 4 bolt, ARP Fasteners, 2 1/2" Cowl Induction Hood, 600 cfm Performer Carburetor, Torker II Intake, Performer RPM Heads, XE268H Cam, Magnum Roller Tip Rockers, MSD6AL Ignition, Blaster2 Coil, Recurved HEI Distributor, 700R4, TransGo SK, 2.73:1 Limited Slip Dana 44, Terminator Headers, Custom 3" TIG Welded Stainless Exhaust, Flo-Pro Twister Muffler, 4 Wheel Disc Brakes, Oil Cooler