69 Valiant cyl4 not firing?

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Val69_170

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Hi, I am new, I bought a 69 Valiant 100, 225 six. It runs on 5 cyl. Cylinder 4 does not fire, could this be cam, burned valves, rings?

I paid $500 for car. 82K on it original, car was garaged and is rust free. Owner crazy about oiling the whole car.... it drips. No Rust anywhere, so I figured I would fix the engine. Hopefully it only needs a valve/head job.

Help!
 
Even if all of your symptoms are present, the #4 plug should fire if the engine happens to run. Bad rings will smoke, bad valves will spit and smoke. A bad cam will give you a host of problems. But one of them will not be just the #4 cylinder not firing. All will have the same problem, or none of them.

If it does not fire, it is due to electricity. Run a continuity check on the #4 wire to make sure there are no breaks in it. While the wire is off the plug, pull it and make sure it is clean and gapped correctly. If that doesn't turn up anything pull the distributor cap and check the #4 plug terminal inside and out. Look for corrosion and carefully clean it up.
 
Chances are your wire is hosed.....easy diagnosis put a known working wire on number 4....if it fires back up...problem solved
 
Yup, that does make sense. I wonder why the guy selling the car didn't try it? Hmmm?

Worse case I may have to rebuild the head or engine right?

Thanks,
 
Since it is just the one cylinder not firing look for something in the path of the wire. Check the plug, make sure it's clean and gapped correctly with no cracks in the insulator. Check the wire for continuity as well as the cap (inside to outside) and the the rotor and or stator for connectivety throughout the circuit.
 
You're getting good advice on tracking down the no-fire on cylinder four. Tune-up parts and technique suggestions in this thread. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. You'll want to pick up the three books described in this thread. And remember this engine will need periodic valve adjustment.
 
Personally I think you should probably just sell me the car and I will take care of it for you... LOL 69 Valiants are my second favorite A body. I would have to agree with everyone else though and put new wires and honestly go through everything and do a general tune up and lash valves and what not. You should post some pictures of the car though.


Jeff
 
Check the compression on all of the cylinders when you replace the spark plugs. You could have a burnt exhaust valve.

check the compression then squirt a little oil in the cylinder and check again.
If it was low and it improves = rings
If it was low and it doesn't improve = valves.

also check to see if your damper in the exhaust is not rusted shut, it is just under the carb. Sorry I forgot the real name of it.

Good luck
 
Ok, that sounds like a good thing to do. I think I can get a compression tool from one of the auto stores.

You know the guy that sold the car did say the damper is rusted in the exhaust manifold. How does this cause a problem?

Thanks,

Jeff
 
Sorry, not for sale! I just got it. Like I said before it is absolutey rust free and covered in oil. Even the outside of the lower body is coated, the fenders and doors look awful dark and dirty from all the oil.

The previous owner used a garden pump sprayer to repeatedly coat the car with oil....

The interior is decent, the old bad part is the drivers seat is torn. the rest of the seats and door panels are very good, even the headliner .
 
Yes that one, if the Manifold heat control valve is stuck in a shut or near shut position this will burn your exhaust valves eventually.
 
#1 is to do a compression test. Tuning an engine with bad compression is a waste of time, If the compression is good, check everything that is for that particular cylinder ....plug, wire, cap, and something that hasn't been mentioned yet, the distributor cam for that cylinder. I've seen a flat one cause that problem.
 
trapster said:
Okay, if you block off the exhaust manifold, what does it do ?
Click to expand...
Other than the obvious fuel economy and performance problems, the first thing to happen with a stuck heat riser is usually the exhaust manifold cracks.
 
when we first got our 68 slant dart it wasnt firing on number one cylinder. the seller said it was blown head gasket. I took off the valve cover and the pushrod was off from being loose. hooked it up and runs on all now..
 
I will try the easy options first. check cap, rotor, wires, plug. then pull valve cover and go from there.

Thanks for all the help.
 
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