stumped ignition

[Anonymous]

Ok ignition problems of course. 68 mustang with stock 200 I6. Stock points and autolite 1100 carb(new and tuned by mechanic that was not me, worked well for 2 weeks). Now I am having a rough time starting and idling. At speed all is well. Bad stumble at idle. Here is the kicker, if I pull the vacuum line that runs into the top of the vacuum advance module it idles good but alot higher than normal. Where should I start?? Orginal owner had the ign advanced all the way over to where the vacuum advance is touching the dipstick almost. Not getting any knocking at all. I am stumped as to where to start. Any ideas are appreciated in advance!
Points gap set at .027.

PB

 

[Anonymous]

anyone?

 

[Anonymous]

I am thinking the choke is stuck in the on position, I will test that tomorrow and see if it gets any better.

 

[addo]

When you say the car runs better (but at higher RPM) with the carb-to-distributor vacuum line unhooked, are you sealing it from airflow at the carb?

It's worth verifying the choke situation, as you said. Also check your plugs. If the gap is on the small side, and the motor worn or plugs too cool running, you could have plug fouling.

Other thing is if your points were set at 27 thou a few weeks ago, the rubbing block may have worn a little and the gap now much less. Setting points with a dwell meter is probably a better tactic.

Check all your plug wires for similar resistance, too. If it was going OK before, things should be pretty recoverable!

Regards, Adam.

 

[pedal2themetal45]

HI PB
Usualy hard starting and stumble off idle sounds like a Accelator pump..
Varafi that the accelator pump is working : look down carb (motor off) move accelator linkage and see that there is a squart of gas going into the carb with the slightest movement of the linkage.... If this is good then I would move on air/fuel mixture.
Turn mixture screw out untill it just starts to miss screw it back in untill it smothes out. Then turn it in just a little more untill you hear the RPM drop just a little bit... A LITTLE GOES A LONG WAY WITH THIS SCREW I'D START WITH 1/8 OF A TURN AT A TIME.. after this if the idle is a little high then reset the idle to spec.750 w/auto 650 w/manule..
after this use a timming light and varafi timming and reset if nessary. To set timming unhook the vacuum line from the carb and plug it so you don't have a vacuum leak going to the carb ( I think this is why the idle picked up when you unplug it from the dizzy (if you didn't plug it off) it lets extra air into the carb almost like giving it more gas...)
good luck
tim

 

[pedal2themetal45]

HI PB
A couple of other things I forgot..
unhook and plug the dizzy vacuum line in order to CHECK and reset the timming.
Also sometimes the cam in the dizzy that the points run against gets a build up of gunk (old dry greaes and such) this well cause the points to jump around when you rase the idle and this thros the gap off.
Tim

 

[Anonymous]

thanks for the input I will be starting back in on it tomorrow. (tues) Hopefully I can figure it out and not have to take it in again. I have changed my mind about the ignition system too, I will be getting electronic ign. asap moneywise. Hopefully sooner rather than later. Least I got a few things to try in a specific procedure other than just changeing something and trying.

I did not plug the vacuum line so I will do it properly next time too. Thanks again!

pb

 

[Anonymous]

when setting the mixture should it be in gear(with brake on) or neutral or park? thanks

pb

 

[pedal2themetal45]

HI PB AND GOOD MORNING
In park or N eather is oK park is better as the car won't roll on ya... all tho you could just set the P brake.
It could be the timming as well.... When was the points changed last??
If its been a while or you don't know I'd change them while you wait on Dizzy money.. not expensive.. You well need a timming light and a Tach/Dwell meter. Find out what the timming should be and the Dwell deg. should be form the parts store. I'm thinking the Dwell well be something like 28-32 deg. but I'm not sure..
If you do change the points keep in mind that when you change the points the Dwell Or point gap well be most likely different than what it was even only if a deg or two you well have to reset the timming when you are done with the point change.. Changeing the point gap or Dwell WELL change the timming but changing the timming WON"T change the dwell its funny how it does that.. (it does this because when the point gap is smaller they well open sooner and if it is wider they well open later so the timming has to be changed to reflect the gap)..
Good luck
tim

 

[Anonymous]

points were changed jsut a few weeks ago. Plugs, Wires, cap and rotar button. Going to get timing light asap as well. Oh the tool crib is coming along nicer than the car. Thanks again for the help!
PB