my 305 tbi timing retards then advances when i have a timing light on it is it soppose to do this or what .. if not whats making it do this...

 

You got the EST disconnected .. right ?


Make sure to run the engine for a while .. so everything warms up nice ... my timing went up and down a little bit when I set it ...

Heck my engine still runs a bit fast .. but after a while it calms down... by the time I park the car again the rpm is real low .. lol

 

 

[hey ya have a timing light .hook it up to ur motor start it crack the throttle look at the timing mark on the crank and if it retards then advances ..let me know if it does this .. I just rebuilt this motor its out of a rs camaro ever thing is new, sensers,holley tb,msd distributer,heads(1.94),valvetrain, mid cam, stock bore,daul exhaust, holley 225lph fuel pump,burnt chip,.i wired it in to a 80 jimmy and iwant to know if it is soppose to retard then advance whena crack the throttle.. i've played with older non computer controled small blocks non of them ever retared then advanced they advanced right away ... any help form a brother would help thanks man!!

 

Hmmm I think I had that at one time or another ... eventually tracked it down to the IAC or whatever

I'd say... unplug the EST .. connect timing light etc... crank it ... let it run for a little while ... let it warm up..

I can get my idle down to a nice low rumble ... almost right away but.. I don't want to do it that way.. which would be for me to have the car in Park .. and rev it a few times to over 3000 rpm ... cold engine .. nope prefer to warm it up.. or just drive and let it warm up


Either way ... let it warm up.. and see what happens

 

I have been thinking that I have been having problems timing my 305tbi fuel injection.
this is what happens.....
when I put the timing light on the mark (and yes I have done everything your suppose to time it) and when i crank the throttle, the timing mark RETARDS THEN ADVANCES.
Is this normal????
yes the motor is warmed up,and yes i disconnected the wire to the distributer,yes Ive done everything your suppose to, to time a fuel injection motor.
I have worked on many NON computer motors and I never had a timing mark "retard then advance!" It always just advanced when ya crank the throttle.
So as ya can see Im alittle baffled about this.
I have replaced all sencors,msd distributer is new,new HOLLY TBI, mild cam,194 heads, lifters, rockers push rods,daul exhaust.
So any info would be of help....alot! this truck is driving me nuts! lol

 

Checked the IAC ?

 

yes i checked the iac...still i have this problem.

 

You unplug the EST and not the wire to the distributor. Are you sure you still unplugged the correct one? Based on the mods you listed you are in dire need of PROM tuning. The mods you have can no longer be managed by the stock tune. Even if your motor is built perfectly it will more than likey hunt and surge for an idle. Chip work is the only way to make the motor run like it should. Here is what the EST looks like.

 

oh and I forgot to mention that I also replaced the chip in the computer .....have been reading about that part in this site and relized that the chip could be the problem,just got a replacement chip,not a modifid chip...
would ya think that could be the problem?it says that if ya replace alot of different parts,(distributer,tbi,cam etc etc) ,that you would need a higher mode chip.... this could be the problem,will look into it some more..