Engine bogs down when at 2,000 RPM

[TheDude]

I advanced my timing to about 12-14 BTDC. I cannot read the tag very well so I must estimate. The engine acceleration is better. I can chirp the tires a little bit during takeoff but not as much as I used to. When the engine hits 2,000 RPM it starts to bog down. I hope this indicates a problem which can easily be pinpointed and solved. I am going to take the Mustang to work today (2.2 miles away). I do not need to get above 2,000 RPM so the drive will be ok.

Any help would be greatly appreciated.

Thanks

 

[TheDude]

I checked the vacuum advance and the breaker plates moved. This Mustang will not make up its mind. Today after work I had it above 2,000 RPM and the engine did not stumble. I tried a quick take off and the engine was starving for fuel. Could this be the accelerator pump?

If so, do I have to take the carb apart to get to the accel. pump? That is new territory to me.

 

[grocery getter]

with the engine off remove the air cleaner and look down the carb operate the accelerator and look for the fuel. if you see good flow, check for a vacuum leak.

 

[MustangSix]

Which distributor do you have? It's not an old Load-o-matic is it?

With that distributor on a 5200, what happens is this: you hook it up to either ported or manifold vacuum and get it running fine. If you drive it easy, it seems to work ok. But as soon as the manifold vacuum drops, ALL the advance drops out and all you have is the initial advance. The car bogs, it gets bad mileage, and it may run warm.

You could get the same symptons on a later distributor if the mechanical advance is sticking or worn out. The distributor will be operating primarily on vacuum which drops out as soon as you put a load on the engine.

Pull the cap and try to turn the rotor. You shoud be able to turn it clockwise several degrees and it will snap back when you release it. If it feels the least bit stick or inconsistent, remove the breaker plate and lube the weights and pivots. Look for worn out holes and bushings, if it's equipped with them.

 

[TheDude]

with the engine off remove the air cleaner and look down the carb operate the accelerator and look for the fuel. if you see good flow, check for a vacuum leak.

The accelerator pump is working well.

I am assuming that it is a stock 1968 200ci distributor. I will check the rotor after work today. Yesterday I checked the vacuum advance by sucking on the hose and watching the breaker plates move. That seems to be working.

Thanks

 

[TheDude]

I should have said it is an original distributor, rather than stock. It has Pertronix electronic ignition.

 

[grocery getter]

with the engine off remove the air cleaner and look down the carb operate the accelerator and look for the fuel. if you see good flow, check for a vacuum leak.

The accelerator pump is working well.

I am assuming that it is a stock 1968 200ci distributor. I will check the rotor after work today. Yesterday I checked the vacuum advance by sucking on the hose and watching the breaker plates move. That seems to be working.

Thanks

i'd check for a vacuum leak.

are you using a pcv valve? if you are, double check that...

 

[MustangSix]

Quite a number of "carburetor" problems are often eventually traced to the ignition. A 40 year old distributor can be completely worn out and "look" fine.

 

[TheDude]

The spark plugs are very dirty. Could an incorrect timing setting cause this? I know my air/fuel mixture is fine.

Yes, I am using a PCV valve. What exactly do I check for? How can I tell oif it is operating correctly?

Thanks

 

[LaGrasta]

pcv... as long as it rattles when you shake it if I'm not mistaken.

 

[TheDude]

I am still having trouble. The distributor I have has two vacuum hose connections. I am still confused as to what distributor this is. I am thinking about getting a new distributor. Which would you recommend?

Thanks

 

[66 Fastback]

I doubt the timing is making you plugs foul. It sounds like a carb issue.

With respect to the distributor:
With two hose connections, I bet the distributor is 1968 or later. Have you got both nipples connected to vac sources? Personally, I would not hook up a vac source to the inboard side of the vac cannister which retards the timing for emission purposes. I would then hook up the vac andvance to a manifold source. Then I would "map" out the advance and see where it needs to be improved. Maybe it is lack of centrifugal advance but you need to find out how much advance you have at certain rpms first.

But to repeat, I don't think you necessarily have a distributor issue unless a deteriorated system is causing plugs to foul.
Doug