Am trying to diagnos a problem on a tune port in a street rod.
86/305, using a speed density ECM.
Problem is: When I attempt to set base timing at 6*, I disconnect the ESC bypass, and look for the 6*... The first time I did this, it was waaay higher. Adjusted the dist to get the 6, and the engine won't start. I checked the rotor position.. dead on.
Adding timing w/ the dist will allow it to start, but run poorly. I added timng, shut it down, reconnected the ESC connector, disconnected the ECM power, then restarted the engine.. Way too much at idle.. 36*. Disconnected the ESC bypass... still 36*. The exh fumes are terrible, indicating a problem.
Someone mentioned that the dist module taking a crap will do this. Y? N?...

NE input is appreciated!

 

Never seen a module cause it, could be that the outer ring of the harmonic balancer has drifted causing your timing mark to be in error. A TDC check with a piston stop on cyl #1 may be in order.

 

Thanks for the reply....
The customer had replaced the original balancer, as it had shucked the outer ring off location.
I wondered if the correct replacement was used. He said they checked the pt # several times, to be sure...
I'd guess it's not.
The piston stop is the next "stop".

Thanks, again!

 

Also the 5.0 and 5.7 had their respective timing indicators at different locations on the front cover. If a 5.0 balncer is installed with a 5.7 timing indicator...well you get the picture.

 

this engine 10 yrs ago, using all the original components, such as the ft cover, pan, yadda, yadda.
I'm confident that the cover is correct. And, as you mention, the balancer is likely a 350 item.
[The customer thot he was dealing above the intelligence level of Autozone, when he went to a parts store that knows better. NOT!]

I'll do the stop deal, and remark the balancer... All should be good to go, then.

Thanks for the help

 

i used to have an 86 TA with the TPI. the balancer for the 305 carb is different than for the 305 TPI. the carb version had the timing mark on the balancer at 12:00. the TPI motor put it around 2:00. reason being is the TB hung over the water pump blocking the view of the mark from behind the water pump.

so, most likely he got one for the 305 carb motor and not the 305 TPI motor. the 305 TPI balancer is the same as one for a 350.

 

actually, if it was a 350 one, it would be the correct one. so, the autozone intelligence went 305 carb for 1986, not 305 TPI.

 

https://ls1tech.com/forums/showthread.php?t=606592

 

It is unfortunately not quite that simple. There were a whole bunch of different combos for different applications. He could have a balancer for a 267,305,or 350 that could have the timing mark at either position. And on top of that to add confusion, I have personally seen balancers with two timing marks. The best way to find out for sure is to use a piston stop.

 

responses.
The positive stop diagnosis is the next operation. I'll just remark the current balancer, and call it good. This "thing" is so much "fun" to work on, too. NOT!