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Discussion Starter #1
Installed a new Autolite distributor, cap and rotor while installing a Pertronix Igniter III today. After setting the timing to 10* BTDC I hooked the outer diaghram of the vacuum advance to the carb port and plugged the inner diaghram since i'm missing the valve near the thermostat housing that would complete the dual diaghram setup. Set the idle to 550 rpm in drive and adjusted the fuel/air mixture. Everything seemed fine but as soon as I backed out and drove down the street the engine consistently died while applying brakes. Any ideas?

Cory
 

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Installed a new Autolite distributor, cap and rotor while installing a Pertronix Igniter III today. After setting the timing to 10* BTDC I hooked the outer diaghram of the vacuum advance to the carb port and plugged the inner diaghram since i'm missing the valve near the thermostat housing that would complete the dual diaghram setup. Set the idle to 550 rpm in drive and adjusted the fuel/air mixture. Everything seemed fine but as soon as I backed out and drove down the street the engine consistently died while applying brakes. Any ideas?

Cory
My 68 started cold, fast idle kicked in, then died,I had knocked off a vacuum hose
to the carburetor port. If you have a power brake booster,I'm guessing maybe it's
leaking and your running too lean. I guess a vacuum gauge would solve that.
 

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Discussion Starter #3
My troubleshooting thus far has led me to suspect the vacuum system may have a leak. As this is one of my weakest areas, I have yet to begin troubleshooting the vacuum system. Thanks a lot for the quick reply and advice.
 

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Sounds like you may have a bad brake booster....see if your idle alters when you step on the brakes vs when not. You can always cap off the booster vac and see if it runs better...
 

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Discussion Starter #5
The idle does not alter when I step on the brakes; this problem only happens when the transmission is in gear. I also need to add that I have yet to really tackle the vacuum system in this car. It is an A/C car but does not have the reservoir on the passenger side near the firewall and all A/C function is not hooked up. The reservoir in the fender is there, but has not been hooked up or tested for condition. Currently the intake manifold is connected to the vacuum junction block and the small vac outlet is running to something in the cabin(though I understand it should be running to the valve I do not have on the thermostat housing). The junction block has all of it's hoses on it but the ones running to the reservoirs are plugged off with screws.

Cory
 

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Isolate the problem by plugging the vacuum lines. Cars from the 60s have tons of vacuum lines. Once you have eliminated the leaks your idle in drive should be fine. 550 rpm in drive sounds right.
 

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Do you have the + wire from the Pertronix unit connected to the + wire/terminal on the coil? Voltage drop through the resistor wire at idle in gear is not sufficient to power the ignition unit properly.
 

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+1 to that thought....I forgot about that issue.
 

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i don't know about pertronix iii ,but the pertronix ii is far more forgiving than the orig pertronix
doctordesoto
Either way, 6ish-8ish volts isn't enough for reliable performance.

Should be easy to isolate the vacuum lines and double check the Pertronix unit. My money is on the wiring, if it ran properly before the installation. If not, well, it could be a lot of things.
 

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Discussion Starter #11 (Edited)
The car ran "fine" before the ignition install. That being said, the engine has never run great. It did not die upon brake application before the install.
So I just capped off the brake booster and headlamp system at the vacuum tree, car still dies upon firm brake application. Btw, manual brakes are not very good on the Cougar. I also discovered that my headlamp switch has a vac leak when connected, but since it was capped off I know it is not the cause of "this" problem.
I've also checked the voltage at the coil + and it is about 11.5 volts. Because of the low voltage, I tried driving with the + hooked straight to the battery, car still dies on brake application.
Anyone else stumped?
 

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Discussion Starter #12 (Edited)
Let me also add that after installing the Pertronix III, I set my timing to 10* BTDC in accordance with the owner's manual. Based on how much I had to move the distributor, I imagine the pre-install timing was set much much higher than 10*. I am not sure since I didn't check the timing before the install.
I also added the vacuum tree on thermostat housing. It is hooked up correctly as per the MustangsUnlimited diagram I got with the hose kit.
 

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Hey.

Did You disconnect the vaccum from the distributor before set timing?

/Tommy.
 

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here we go again---i think you answered your own problem----put a vacuum gauge on one of the intake trees and advance the dist until you get the highest reading---lock it down---if it doesn't bog when starting , your probably close--also you said it did'nt run good prior to this--i'm betting thegasket under the carb or under the heat spacer is wrong and you have a bad vac leak
doctordesoto
 

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Discussion Starter #17 (Edited)
After setting the timing, I plugged in both vacuum hoses to the vac advance.
I will check for the vac leak under the carb. I'm not inclined to think this is a problem, since I rebuilt the carb last fall.
So are you suggesting that the engine requires a higher timing to produce enough vacuum? That is a good thought, I will do some adjusting tomorrow.
As far as the car never running well before, the main symptom has always been a flat spot when coming off the line. I have to kind of feather the accelerator to keep the engine running. After getting up to speed, the problems go away.
 

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Discussion Starter #18
By intake tree, are you saying I should measure the vacuum off the ported vacuum from the carb or the vacuum off the intake manifold?
 

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manifold vac--is what you need for this---i'm still suspecious of the gasket under the carb--the std on from napa for a square is not big enough and allows for a vac leak
doctordesoto
 

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Have you been in contact with the PERTRONIX folks? I have never installed their unit, but the fact that it didn't do this BEFORE says a lot about the install, or the product, IMO.

Dale in Indy

P.S. I haven't read the complete thread, so maybe you have.
 
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