knuckless

Ok i cant think of any other way to explain it but when i floor it from dead stop or under 10mph the engine jumps/lunges like its trying to get out of the engine bay and i hear a thud like the engine landing back into the bay. the pedal gets sucked down away from my foot until i release the pressure. when im crusing anywhere around 20mph or so it doesnt do this at all when i floor it. i did it when taking a turn around 10mph and the car did the same thing but i heard a grinding noise almost like a starter grinding.

this only happens for a second or so because i let go of the gas immediately cuz i have no idea whats going on

its a 289 with an automatic transmission and edelbrock 1406 600cfm carb
this doesnt happen when im in park and i floor it, it revs perfectly

i got no ideas

jspagna1

Sounds like a broken motor mount to me. It won't do it when your in park, but in gear your putting torque to the motor. That's what my previos Mustang did when I broke a motor mount.

racin66coupe

that or a transmission mount/ crossmember mount

67mustang302

Check your engine mounts.

tempoffroad

motor mount

JamesW

or the latin version...

Mountous Motori

knuckless

hahaha im thinking motor mounts?

yeah i sorta thought maybe to check if they were loose once i posted this, well ill go check right now and hopefully they arent broke

knuckless

ok check that. motor mounts are fine, at least they seem fine to me, its dark but basically i looked to see if anything was broken

anything else i should check on the motor mounts?

109jb

You might not "see" anything. What happens is that the rubber either splits or comes loose from one of the metal pieces of the mount. With engine torque it rocks over and when it plops back down it is in the same spot it should be. Hook a hoist to the motor and pull (But gently) like you are pulling it out of the car. A broken mount will be obvious. You could also put a block of wood under the pan and gently jack up on the motor, but you could also dent your pan.

Gun Jam

no they are broken....check better....You might even try jacking the engine up carefully from a strong point on one side (I have not broken anything yet by carefully using 2x4 and placing one end on the radius of the oil pan lip where it bolts to the block on the front of the engine near the timing chain cover...use the bolt heads on the radius for support be careful other end goes on the jack.)

Its going to be the drivers side that is broken... start there inspect with good lighting

-Gun