1972 351C runs crap

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Odmark

Well-known member
Joined
Dec 1, 2015
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Location
Sweden
My Car
1972 Mercury Cougar
Hello. My issue is not regarding a mustang, but a 1972 Mercury Cougar with a 351 Cleveland 2v engine. But i figure this is about the same car so hopefully i can get some assistance here.

The problem is that i cant get it to run properly, when i bought the car it did not even start.

The previous owner was driving it and it just died with a small bang. He has replaced the timing chain since that was a bit slack, but not jumped if i understood him right.

And like i said, still no start. Since then i have now tdcd the Engine and set the distributor right, and set the timing right with a timing light, since it was way off. And replaced all the spark plugs.

Now it starts, and idles (even though a bit rough), but the Engine feels very sluggish and wont rev past 2000 rpm.

Also it only idles for about 20 seconds max Before dying.

No knocking from the Engine or so, the rocker arms seem to be moving as they should.

Carb is an 650 edelbrock 4bbl, maximum 2 years old.

Do you guys have any idea what can cause this? Thanks in advance, hope you can help a Cougar cousin out :D

 
Well i am not a engien guy but one thing I would say dont start it up! Your have to have it inspectet of a engine guy! If you don't Now hove to do engine work. But it could be the destrubiter wheel! Since you said that it was way off!! Hobe you can get some help.... Regards Lars DK

 
Check for missing or loose vacuum caps, hoses etc...

Check to see if the fuel filter and/or carb is clean.

Test for spark at every cylinder.

Do a compression test.

Check distributor gear roll pin.

 
Welcome Cousin! Your situation is harder since it was not running when you bought it and someone else did some work to it.

The very next thing you should do is a compression test. Post the numbers up here. If the numbers are high and consistent you know you are getting good compression. Then it will just be a matter of making sure the fuel and ignition are working correctly.

 
Could be different things, but since the car died with a boom, could be damaged inside the carburetor, like with a back fire, could damage the power valve. The big lack of the timing chain could move the right timing... I guess.

 
What is your timing set to? The "standard" 6* BTDC usually doesn't cut it with Clevelands - I know when mine was set there it ran like crap. Did some research, discovered it likes things better around 16*-18* BTDC. If it was initially set to 16*-18* BTDC, that would qualify as "way off" for folks experienced with most other engines. ;)

Also, check your points, coil, plug wires, cap & rotor, and other electrics. Consider swapping over to an electronic ignition (Pertronix, Dura Spark, MSD, etc.)

I'm assuming you have a 4bbl intake since you mentioned the engine is a 2V. Check the intake for any kind of identification - the previous owner might've not known that you can't simply jam a 351C-4V intake onto an engine equipped with 2V heads so they can have 4bbl carb option. It's a long shot, but worth a look - I've heard a 4V intake on 2V heads will cause similar issues as well.

As for the Edelbrock carb, the idle/air mix adjustments could be off, the needle valve and/or accelerator pump might be sticking, and if you have the timing's vacuum advance on the wrong port, it could have issues as well. Mine's on the driver side port (manifold vacuum - for non-emissions vehicles) vice the passenger side port (timed vacuum - for emissions-controlled vehicles). Idle/air mix adjusters are the thumb screws on the front of the carb - both should be very close to each other in adjustment. Best rule of thumb is to close them (clockwise) completely, and back them out 1.5 turns each, then tune accordingly for best idle and acceleration rate.

Your best bet is to download the manual for your carb and make adjustments accordingly.

Hope that helps! ::thumb::

 
something like this i would not entertain anything else until i did a compression test.

could be a wiped cam also.

the bang happened for a reason, was it mechanical damage or something else.

if the compression test checks out then i would move forward.

 
,

in addition to the things mentioned above

1. check the plug wire routing then check it again

2. disconnect and plug the vacuum hose that goes to the distributor and leave it plugged.

3. plug the pcv valve port and leave it plugged until it runs right.

4. set the timing to 12 degrees btdc with the dist vac hose plugged.

5. connect the timing lite to each plug wire to see if it is sparking.

6. turn the left fuel mix screw all the way in while counting the turns to see if the idle lowers then return it to its previous position.

7. turn the right screw in and do the same thing.

If one of the screws has no affect on the idle, the idle port on that side is not working.

If both screws have an affect, your idle circuit is working.

8. with the engine idling, gently spray flammable carb cleaner with the long nozzle around the carb base and intake manifold where it bolts to the head . . if the rpm goes up, you have an air leak.

5. turn

 
Thank you for all the replys! I will start troubleshooting this as soon as i fix the issue with the key stuck in the ignition.

Bought a HEI dist with new cables as well just to get the ignition system all fresh!

 
Small update, i know im starting in the wrong order here but if i need to rebuild the Engine i would buy this stuff anyway.

So i have now installed:

New HEI distributor with new wires and plugs

New Ignition switch since mine seemed to be broken

New Fuel Pump

New Fuel Filter

THOROUGLY dissasembled and cleaned the carburator, adjusted floats that where way off etc, new gaskets.

So now the whole ignition system is fresh, and fuel delivery fresh, if the lines are not clogged that is.

I also installed a vacuum gauge to read when starting it up.

Going to do the compression test as well Before reinstalling the plugs.

 
The plugs where all black, not wet though.

And a few of them were cracked in the ceramic so they just fell apart.

No headers but manifold-back is homemade 2 1/2 inch pipes.

 
I replaced the plugs earlier though with minor difference. Smoother idle but still wont go over 2000rpm.

Did not have time to do anything today. This engine is a pain in the ass to screw down the compression tester. Really tight fit.

 
Okay... problem... the new fuel pump is doing great, filled the filter up almost instantly (with the old pump the filter was just about 1/4 filled).

But now i got absolutely no spark on any of the plugs!!

This is with my new HEI distributor.

I have steady 12V to the dist with the ignition on, but no spark at all.

The rotor is spinning as it should while cranking and i cant see anything wrong.

All new cables (8mm accel) and champion plugs.

Could the new distributor be faulty? :shootself::-/

 
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