[James 72 240Z]

fresh L24 with 79-80 zx distributor.

checked cam timing, distributor/oil pump alignment, etc. initial timing set to 12 degrees.

when revving the engine the timing advances to about 20 degrees just before 2000 rpms then starts to retard. as i rev the motor more it misses and the timing retards to about 10 degrees.

on the road acceleration is smooth to about 2000 rpms then hiccups and backfires out the carb. if i feather the throttle i can rev the motor higher but certainly can't stomp on it. idle is good, but not perfect...very slight miss at idle. synced and balanced carbs, float levels are good and plugs are nice and tan.

i'm thinking mechanical advance which i'm going to test based on this info:

http://www.zcar.com/forums/read.php?f=1&i=204169&t=204119

also, would the needles have anything to do with the above behavior?

thanks in advance for any replies.

 

[James 72 240Z]

One other piece of info...

...the vacuum advance unit has two outlets. the one closest to the distributor seems to do nothing so i just plugged it. the other outlet appears to work the vacuum advance. i can draw vacuum, hold it and it doesn't move/leak.

 

[James 72 240Z]

Checked mechanical advance

unhooked vacuum advance, plugged everything and when i revved motor timing retarded. guess the distributor goes back to MSA now.

 

[79-280-ZX]

Please check this update...

http://www.zcar.com/forums/read.php?f=1&i=229859&t=229699

The post you refered to was for a different problem. You may find the above post more expanitory.

Wayne Monteath
Masham, Quebec.

 

[zmattrun]

Re: Please check this update...

hey james
I've had this same problem with my 240 for the last couple of months, and no one has been able to help, they mostly pawn me off as stupid or misguided....


will you keep me posted with any findings you discover, I'll be happy to let you in on how I mask the problems simply to get rid of the symptom....but I've yet to attack the actual problem

matt