Hunting down an engine vibration

Flavadave4

Active Member
Nov 28, 2003
1,044
20
49
Utica, NY
Helping a buddy work out this problem. Its a 1990 LX, M&R 331, Trick Flow TW heads, X cam, TFS Intake manifold, 30lb injectors.

He and another friend installed the heads and rest on this supplied shrt block. The car idles fine and drives but has a nasty vibration in the mid RPM's, so bad that it cracked his bell housing, mounting ears on tranny and mounting ears on the starter.

He suspected the engine might not have balanced correctly and the builder agreed to check it over, pulling the motor and trans from the car we discoverd tonight that on the driver side head the front 3 chambers looked as they should with a clean light color on the valve, spark plug and walls, the back one was black, with a nasty residue and a slight dark fluid trace around the top of the cylinder wall and the plug was black.

He did bring it to a dyno last summer to see if they could tune it but every time they would go to make a pull there computer was showing it leaning way out...i think they best pull they go to was 217hp or something like that.

Bad injector?


I'll see if he took any pics of it but I was just curious if any one has dealt with a really bad vibration like this and if it could be injector related?
 
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