Mercury Cougar Owners banner

1 - 14 of 14 Posts

·
Registered
Joined
·
34 Posts
Discussion Starter #1
Hey guys, I am having an annoying issue that I can't seem to fix. I have a hesitation when accelerating from a stop. It bogs like it's fixing to stall, then catches and takes off. It never dies, just comes close. Now, I have rebuilt the autolite 2100, set the point gap, set the timing at 6*, and I just bought a new vacuum advance since the old one was bad. I have no vacuum leaks either.

Now, the only thing I have found that helps is advancing the crap out of the base timing, but it starts pinging badly when I do this and it looses all low end grunt. Any ideas?

1970 Cougar. 351c 2V, 3 speed auto.
 

·
Premium Member
Joined
·
2,142 Posts
Even though you've rebuilt the carb, it sounds like it's starving for fuel. Squirter is not providing enough gas until the airflow thru carb can get the boosters going.
Any chance you want to dump the 2V carb and intake and set it up for a 4V?
 

·
Registered
Joined
·
34 Posts
Discussion Starter #4
Even though you've rebuilt the carb, it sounds like it's starving for fuel. Squirter is not providing enough gas until the airflow thru carb can get the boosters going.
Any chance you want to dump the 2V carb and intake and set it up for a 4V?
I have tried multiple settings on the accelerator pump to no avail. I don't see how it's starving since it's stock. I may have the idle mix too lean to start with. I am making this my daily driver, so I would like to see at least 17MPG and I doubt I can get that with a 4v. Currently it's abysmal, but the vacuum advance wasn't working, so that explains the poor mileage.

is the dist on ported vac
Ported? How I have it setup is the vacuum line comes off from the carb and goes to the temperature valve, then off from the temperature valve, it goes to the primary port on the vacuum advance. Then I have a line coming off from the intake that T's, one side going to the second port on the vacuum advance, then the other side of the T going to second port on the temperature valve.

I think that is right, but the previous owner had all of this disconnected, I am just trying to follow the shop manual.
 

·
Registered
Joined
·
349 Posts
Even though you've tried different settings on the accelerator pump, does it actually spray two strong jets of fuel when you manually move the accelerator linkage while looking down into the top of the carb? If not, you've got some more cleaning up of that carb to do.
 

·
Registered
Joined
·
34 Posts
Discussion Starter #6
Even though you've tried different settings on the accelerator pump, does it actually spray two strong jets of fuel when you manually move the accelerator linkage while looking down into the top of the carb? If not, you've got some more cleaning up of that carb to do.
Yeah, two strong jets of gas come out. That was one of the reasons that I rebuilt the carb in the first place, one side was clogged up and not shooting gas. And when I say rebuilt, I mean stripped, the housing covered in lacquer thinner for two days, then all passages sprayed out with carb cleaner and then air.
 

·
Premium Member
Joined
·
13,577 Posts
17 should be no problem, I get over 15 on my 351C which is somewhat "warmed over". Run the ported vacuum connection from the carb directly to the vac advance. If you have a vacuum reatard port on the advance can, leave it open. What is your initial timing set to?
 

·
Registered
Joined
·
34 Posts
Discussion Starter #8
17 should be no problem, I get over 15 on my 351C which is somewhat "warmed over". Run the ported vacuum connection from the carb directly to the vac advance. If you have a vacuum reatard port on the advance can, leave it open. What is your initial timing set to?
Ok, I will give that a shot. Initial is set at 6*, but it runs much better when it's set to 13*.
 

·
Registered
Joined
·
34 Posts
Discussion Starter #9
Went out and did as you suggested. Just went off from the carb to the vacuum advance, bypassing the retard port and the temperature control. Hooked up a vacuum gauge and set the idle mix screws, pulling 20 inches of vacuum at idle now. That seemed to help, but not enough, so I advanced the timing. Got it to the point that the hesitation is barely noticeable and the car is completely driveable now. It's pinging just a little bit at 1/2 throttle, but that is likely from the 87 octane that I am using. Going to start running 93 in it.
 

·
Registered
Joined
·
34 Posts
Discussion Starter #10
Well, it started getting worse again, so I went back to the drawing board. Changed the spark plugs and wires since they were old, set the idle speed, set the timing, set the idle mix screws, double checked for vacuum leaks, set the vacuum advance on the ported vacuum, filled up with 93 octane. 6* timing just doesn't work, it hesitates badly, so I set it to 14*. The accelerator pump is on the strongest setting, it engages immediately with two strong jets of gas. I am pulling 21 inches of vacuum at idle. Still the hesitation is there. I also found that if I go WOT, it stumbles at little bit.

Any other suggestions?
 

·
Registered
Joined
·
245 Posts
You need to double check your harmonic balancer to make sure it hasn't slipped on it's core. You will have to find top-dead-center on the number one cylinder, then check with the timing pointer to make sure that the balancer is at zero. I time every engine, with a distributor, using a dial timing light. I leave the vacuum advance connected, set the dial at 34 degrees, and time the engine with the rpm between 2600 and 3000.

You may have a cam timing problem...posibly a stretched chain.

You also need to make sure that you have the #5 and #6 plug wires separated in the looms...they are known for crossfiring.

By the way, 17 mpg is easy to get with a 600 cfm Edelbrock...jetted properly.
 

·
Registered
Joined
·
245 Posts
Also...are you running points? Have you set the gap and dwell? Do you have one or two vacuum ports on the distributor? When this is all said and done, I think you should make the switch to a 1978 F150 351M distributor, cap, rotor, ignition box, and Autolite AP26 plugs. That combo will burn any gasoline, takes the trouble out of points, and improves fuel economy and performance.
 

·
Registered
Joined
·
34 Posts
Discussion Starter #13
You need to double check your harmonic balancer to make sure it hasn't slipped on it's core. You will have to find top-dead-center on the number one cylinder, then check with the timing pointer to make sure that the balancer is at zero. I time every engine, with a distributor, using a dial timing light. I leave the vacuum advance connected, set the dial at 34 degrees, and time the engine with the rpm between 2600 and 3000.

You may have a cam timing problem...posibly a stretched chain.

You also need to make sure that you have the #5 and #6 plug wires separated in the looms...they are known for crossfiring.

By the way, 17 mpg is easy to get with a 600 cfm Edelbrock...jetted properly.
I will double check to make sure that the harmonic balancer hasn't slipped tomorrow. This seems like a fuel issue to me, something that I forgot to mention is that I can double tap the gas, like you would on a car with a bad accelerator pump, and it wont hesitate.

Also...are you running points? Have you set the gap and dwell? Do you have one or two vacuum ports on the distributor? When this is all said and done, I think you should make the switch to a 1978 F150 351M distributor, cap, rotor, ignition box, and Autolite AP26 plugs. That combo will burn any gasoline, takes the trouble out of points, and improves fuel economy and performance.
Yeah, still on points and the gap and dwell are set. The old vacuum advance had one port, but the car originally had the setup for the dual port, which is what I have now. Still, I am not running the second port, or using the temperature control valve. I just ran a line off from a ported vacuum on the carb to the primary port on the vac advance. I considered the Pertronix II ignition, but I will look into what you suggested.
 

·
Registered
Joined
·
245 Posts
I will double check to make sure that the harmonic balancer hasn't slipped tomorrow. This seems like a fuel issue to me, something that I forgot to mention is that I can double tap the gas, like you would on a car with a bad accelerator pump, and it wont hesitate.



Yeah, still on points and the gap and dwell are set. The old vacuum advance had one port, but the car originally had the setup for the dual port, which is what I have now. Still, I am not running the second port, or using the temperature control valve. I just ran a line off from a ported vacuum on the carb to the primary port on the vac advance. I considered the Pertronix II ignition, but I will look into what you suggested.
Yeah, the dbl tap on the accelerator does help with the diagnosis. Have you checked the vacuum at the distributor on acceleration? Back to the carb...a good dual plane intake and a 600 Carter AFB type carb would be an excellent add on, but I strongly suggest the AFB tune book and rod & jet kit. I was getting 17 mpg out of my '70 4V before I went radical.
 
1 - 14 of 14 Posts
Top