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Discussion Starter #1
So I am at a loss after messing with my cougar for the past 2 months and trying to get her tuned for car show season. Assuming that it stops raining here and flooding.

So here's all the information.
-Rebuilt 302 with 7000 miles on it
-Holley 4160 series carb, model 1850C with electric choke
-All new vacuum hoses
-Petronix1 points eliminator kit installed

So here is my problem. The dumb thing won't tune. If I get it tuned so that it's idling great at about 750 RPM then when I put it into gear it drops to about 300 RPM and the car shakes and shakes. If I adjust the curb idle screw and the mixture screws so that it is doing about 550 RPM in gear then when I put it in park it goes up about 1200 RPM and I know that is way to fast. I have rebuilt the carb. I have tried timing the car everywhere from 8* all the way up to 16* with no luck. I've checked all my hoses for leaks or cracks and they all check out. I just can't get this thing tuned and it's driving me nuts. Any ideas?????
 

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Doesn't sound like it's your tuning that's the issue but the drop when it's under load and in gear. I'm going to go with a vacuum issue as well. When you rebuilt the 302 did you use a stock cam grind or aftermarket? Might want to check what the vacuum is at idle in park and when you put it in gear.

If vacuum levels look ok I would look closer to the trans hook ups for vacuum. Is the trans in good shape? Was it rebuilt as well?

Sounds like your engine is running great if you can get it to tune in Park. Best of luck.
 

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Discussion Starter #4
Doesn't sound like it's your tuning that's the issue but the drop when it's under load and in gear. I'm going to go with a vacuum issue as well. When you rebuilt the 302 did you use a stock cam grind or aftermarket? Might want to check what the vacuum is at idle in park and when you put it in gear.

If vacuum levels look ok I would look closer to the trans hook ups for vacuum. Is the trans in good shape? Was it rebuilt as well?

Sounds like your engine is running great if you can get it to tune in Park. Best of luck.
When the engine was rebuilt we used the stock cam. The engine hasn't been modified in any way other than the aftermarket holley carb.

As for the transmission it's not running a C4. I did the AOD swap in it so it doesn't run off of vacuum but linkage off of the carb.

I'll go check the vacuum and let you know what I find when I get off work.
 

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the spacer under the carb is leaking vacuum---look real close---the gasket the autoparts store give you only covers about .040 of the spacer
doctordesoto
 

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i had similar issue on mine. swore there was no leaks. but in the end it ended up being the vaccuum advance on the distributor. made sense to me. it happend when i did a small burn out for the first time. first real load on the motor and then it started idling around 300. had to give it stupid amounts of gas to keep it running up the drive way. and then everytime i put it in gear it died. must have blown a seal or somthing in the vacuum advance. pretty sure it was the origional distributor so it was bound to happen. scared the crap out of me after that burn out thought i was gonna have to pull the motor.
it would stay in gear when i adjusted the carb but out of gear it would go back up to 1200+ like your explaining. and mainly in reverse if i tried backing up it would just die regaurdless unless i floored it haulin ass in reverse. stumped me for a while. timed it a million times too.
anyway, check it out man. you might need new distributor.
after that it was imediately running perfect after a few adjustments to the carb since i messed with it so much.
 

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Did you disconnect the vacuum advance when setting the timing?
 

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Is the distributor diaphragm connected to the ported vacuum or manifold vacuum?

May very well be a vacuum leak but coug67 may have nailed it, advance coming in at a low RPM making the idle unstable.
 

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Discussion Starter #9
Alright so here is a question I have. On the front of the car you have the vacuum tee. two of the lines head to the carb and one to the vacuum advance. I am wondering if even though I have my lines hooked up according to the 68 shop manual if they are hooked up wrong. When I pull the vacuum line off of the distributor there is no vacuum being pulled through it. Right now the T starting at the top fitting has the line from the front of the carb, then the vacuum to the distributor, then the vacuum line from the rear of the vacuum T on the back of the intake manifold.
 

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My Cat starts almost immediately and idles smoothly every time I go to drive it.

Edelbrock carb, Pertronix ignition conversion. I haven't had to fiddle with it for a long time.
 

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My Cat starts almost immediately and idles smoothly every time I go to drive it.

Edelbrock carb, Pertronix ignition conversion. I haven't had to fiddle with it for a long time.
We all appreciate your bragging. ;)
 

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Is it just a plastic T? If it is, get rid of it. You don't need it. On AC cars, there was a heat activated vacuum switch built into the heater hose elbow that switched from manifold vacuum to ported vacuum after the engine warmed up (see picture). Non AC cars did not have this. The top one goes to your carb (ported vacuum), middle to distributor advance, bottom to manifold vacuum.



EDIT: It was built into the heater hose elbow in 67. In 68, the heater hose elbow and heat activated switch were split.
 

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The ported vacuum switch or the vacuum T as you call it doesn't let the spark advance until the coolant gets hot. On a 43 year old car, it's more than likely bad anyway. I removed the switch and plugged the hole in the thermostat housing with a 3/8" NPT plug. You can replace the switch if you choose to do so, still available.
The main thing, make sure you're you're not using manifold vacuum to actuate the vacuum advance. Ported vacuum only.
If I do this then what is the purpose of the vacuum T at the front of the car? Also what would I end up doing with the line that comes from the back of the vacuum T from the manifold on the rear?
 

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So does mine, life is good.
My Cat starts almost immediately and idles smoothly every time I go to drive it.

Edelbrock carb, Pertronix ignition conversion. I haven't had to fiddle with it for a long time.
 

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Discussion Starter #17
This would be the vacuum T I was talking about. I was going to try and tune her and get the vacuum reading for you guys but at work we got super busy and had to stay late. Oh the joys of being a poor college student with a job that will work with school.....
 

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Nobody else here has to work around their day job schedule, we all just do what we want when we want.....
 

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LOL --- Good one!! I used to think I wanted a career - turns out I only wanted the paychecks.....
 
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