Help needed...can't get stock 289 to run right...

COE Dan

COE Dan

Senior Member
Ford Barners,

Here's my issue: I can't get my engine to start and idle smoothly.

Background: The car is a 66 Falcon with a stock 289 with C-4 transmission. I rebuilt the engine about 4500 miles ago. I was recently having issues with fluctuating mid-range cruise rpm but I solved that by installing a new distributor (the old one have a bad vacuum advance which was apparently causing the problem). So, the points, condenser, distributor are all new. I checked and cleaned the rotor, cap and coil and all tests indicate proper operation. I've also pulled and rebuilt the Ford 4100 4-bbl carb. I've replaced all the gaskets to include those in the thermostatic choke assembly and those under the carb and carb spacer. After attempting to run the engine I've opened the carb and the float level appears correct and there is fuel in both bowls indicating the fuel pump is working correctly.

Here's the symptoms: Upon startup, the engine will fire erratically, stumble, miss and usually quit. Length of cranking, pumping more fuel to the engine or waiting and trying later doesn't work. Occassionally, it will start and run smoothly as it should. However, once it warms up and the choke opens all the way, the engine starts running rough and eventually stumbles to a stop.

I've checked the vacuum and when I can get it to run, I'm pulling about 15 inches. I've attempted to adjust the idle distributor advance but no change is evident. I've isolated the vacuum (disconnected the vacuum accessories, and auto trans modulator line. I've also attempted startup with and without the vacuum advance connected. I've also checked to see if the distributor vacuum source is working and it is.

I'm at a loss to what to work next. Most of the shops that I've gone to say they can't troubleshoot the car or they don't have time.

Anyone have any ideas on what to try next?
Anyone have any suggestions on good service places on Oahu, Hawaii?

Thanks much,

COE Dan
 
Put the old condenser back in and see what happens,I had a problem similar to yours the new condenser was a dud.
 
If a different condenser does not change anything, its time for a compression check. It sounds to me like one of two things, a vacuum leak at the intake manifold gasket, or valves not sealing well. That motor, with a stock cam, should idle at 21 inches of vacuum, not 15.
 
Unfortunately, the old condenser was still in the distributor I sent back for the core deposit. I'll have to order another to test that theory. I did to a primary circuit check per the Ford shop manual and when cranking with a remote switch, I get a steady pulsing spark from the coil high tension wire which is why I don't suspect the coil, points, condenser or resistor.

The shop manual also suggests a potential for an intake manifold leak...I'm hoping it's not that or a valve sealing problem.

Thanks for the inputs, I'll do those checks.
 
Retorque the intake manifold. The way these intakes fit you have to retorque them two or three times so they settle in right. I have had to do that on the 302's I've had rebuilt.
 
Well, I tried the retorque...while the manifold needed it, it didn't solve my problem.

I didn't have this problem before I installed a new distributor. So, going back to the last known good point, I pulled the distributor and took it apart. Everything looked to be in order with the exception of one thing, which I don't have experience on. One of the two centrifugal weight springs is loose when the weights are 'in'. This spring does not engage the centrifugal arms until the weight travel about halfway to their maximum position. This is not the case in and old (unserviceable) distributor. Both of those springs are always engaged regardless of the weight position.

After I reassembled the distributor and placed it in the engine, I was able to get the engine to run smoothly for about 20 minutes and fully warm up with no problems. I was able to rev the engine, rapidly change rpms, etc. with no problems. I was able to retime the engine, check the dwell and the engine was pulling a steady 18 inches of vacuum. There was (and always has been) a slight, less than 1/2 inch, random fluctuation in the vacuum still present. Then, after 20 minutes, the problem came back, the the vacuum fluctuated from 18 to 10 inches a couple of times then the engine quit.

Back to square one...do I have a distributor problem? Can a centrifugal advance problem manifest itself this way?
 
Often, one distributor spring will be very light, the other rather heavy. The heavy may not grab anything untill the weight is part way out. The next thing to do is a compression check. Those heads like to wear out valve guides so bad the valves dont hit the seat square every time. It may be time for a top end job.
 
Thanks for the advice...I rebuilt the entire engine about 4500 miles ago including the heads which is why I haven't suspected a valve problem. I'll do a compression check next to see if I can isolate a cylinder or a stuck valve.

COE Dan
 
Can you borrow a known good distributor? If your compression check comes out ok, try that.

Are you lubing the cam inside the distributor?
 
Since your problem starts when the engine is up to operating temperature, if the issue is a sticking valve, you probably won't see it during compression checks. If it is a valve, I'd guess exhaust. Any change in exhaust note when it occurs? You should hear a big change if an exhaust valve starts to stick.
 
Do you have another coil laying around ? Try swapping the coil and see what happens . You could have a hot & cold coil .

OK , do you have an air compressor of any kind ? What you need to do is run an air line to each cylinder through the spark plug hole . Just 20 lbs or so of air will work . Now listen to see if you hear air coming from the carb , the exhaust and open the oil fill cap and listen there as well . If you hear air coming from any one of those places then you have a problem .
Exhaust = exhaust valve
Carb = intake valve
oil fill cap = ring problems
If you don't have the adapter to do this test , just take a spark plug and break the top off and clean the inside out of the base . Now take a screw in air line coupler and weld it to the spark plug base . That is what you need unless you can find one at your local Advanced Auto parts store .

Let us know how you make out .

Jim
 
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