NEVERL8

Due to popular demand (and oversight on my part), here are the pictures of the fouled plug. All the details are in my previous post.

http://i150.photobucket.com/albums/s...SparkPlug4.jpg

http://i150.photobucket.com/albums/s...SparkPlug3.jpg

http://i150.photobucket.com/albums/s...SparkPlug2.jpg

http://i150.photobucket.com/albums/s...SparkPlug1.jpg

Here is what I know.

Bought the car. Noticed the engine had a vibration after driving it for a few days. It may have been there when I bought the car but just didn't notice it. Decided to check the plugs. The #8 plug electrode was bent over and touching the tip. Obviously the plug was fouled out. Figured this was the cause of the vibration with the #8 cylinder not working. Engine vibration changes with speed and has some resonant frequencies where it noticably shakes the car.

Changed the plug. Put in a new AC45. Ran the car for 30 or 40 miles, still didn't feel right. Pulled #8 and it was not correct. The electrode was not bent over at all, but the plug was beginning to foul.

Ignition wire to #8 was suspect. The boot on the distributaor cap side came off when I was checking the ignition wires. Put on new ignition wire just in case. All the ignition wires were new when I bought it so I did not change the rest of them. Checked the distributor cap but no obvious defect, no cracks or arcing that I could see. The car does has been converted to a magnetic pickup so there are no points.

Pulled all the rest of the plugs. All other cyclinders were firing normally. They are perfect light brown with no abnormal wear, signs of oil or detonation.

Adjusted all the valves according to the 67 chassis repair manual. I have done this before on several other cars so I know I did not screw up.

Did a compression test.
#8 plug compression tested at 150 psi
#6 plug compression tested at 150 psi
#4 plug compression tested at 145 psi
I stopped there and did not test the rest of them. Didn't see the point.

Checked and set the timing to factory specs. It was not off at all so this was not a contributor.

Tonight, 200 miles later, the engine is vibrating even worse.

Pulled all the plugs. #8 is totally fouled out. You can tell by the way the plug was indexed that one side of the electrode was facing the valves and the other side the piston. Electrode is not bent over. All other cyclinders fire normally. All the rest of the plugs are a perfect light brown with no abnormal wear, signs of oil or detonation.

#8 plug compression tested at 150 psi
#6 plug compression tested at 150 psi
#4 plug compression tested at 145 psi
I stopped there and did not test the rest of them. Didn't see the point.

The engine was rebuilt right before I bought the car. Jim did a nice job on it with a lot of attention to detail from what I can see on the outside.

My next step is to put on a new distributor cap and see if this fixes the problem. If not I will put a dial indicator on #8 rockers and measure lift thinking maybe it is a soft cam or bad lifter. Would this be the case given the compression test I did. Can you have a soft cam or bad lifter and still have excellent compression.

If the distributor cap does not work I am flying blind. Any input on this from the forum would be much appreciated.

Thanks
Bruce

Racer-rt

In reading your post I see two points that I think are significant.
First, how or what bent that first plug. Too much coincidence to think that when the set of plugs was installed the same cylinder with the fouling problem also had an accidentally bent plug installed. I think you said the car is a recent purchase for you and so perhaps an unsrcupulous "mechanic" bent the electrode to try to hide the problem. It doesn't make sense, I know but maybe...
More importantly, whats wrong with the engine. The buildup on the plug is for something burning that should not be there. That kind of growth comes from either dirt or oil getting into the combustion chamber and the black shiny color means it is probably oil.
Check the valve guides and seals for that cylinder and if they are OK you may have a broken/ bent damaged oil control ring and or ring land on that piston.
Hope this helps,
Rich

magicv8

IMO it looks more like fuel fouling. If you are not getting a blue haze at the exhausts indicating oil fouling (usually worse at startup for valve seals), make sure the float supplying number 8 is not dripping fuel down the manifold.

NEVERL8

Please elaborate on what you mean by 'float supply on number 8'. I do not understand.

Thanks

knight37128

If you have an exhaust cam lobe going down the spark plug will foul.

Dead cylinder is a big miss. Don't know if it will cause the "vibration" you describe.

Pull the valve cover and measure the lift of exhaust lobe.


P.S. Number 8 exhaust is what went on my cam.

NEVERL8

The bent plug electrode bothers me as well. I have put in two plugs since finding the bent one. Neither of the new plugs have bent electrodes when I remove them. I was thinking of some type of interference with the piston and the spark plug, but this is most likely unfounded.

The valve guide seals do not appear to be the problem. No smoke at all at startup or under heavy deceleration. Also, no smoke that I know of under heavy acceleration. Correct me if I am wrong, but I believe an oil ring problem would lead to blue smoke, especially under heavy load.

Today I will install a new distributor cap. It is my last shot at something simple.

Thanks for the input. I will chew on this some more.

NEVERL8

OK. I planned on measuring the valve lift if the new distributor cap does not solve the problem. I assume I can use a dial indicator and just measure the travel of the valve as I rotate the engine?

The vibration comes from the #8 cylinder not firing I am quite sure. The vibration gets worse as the rpms rise or load on the engine increases.

Thanks

wmf62

silly question maybe, but have you actually checked the spark at the spark plug end of the wire to make sure that it is or is not firing?
Bill

NEVERL8

Not a silly question at all. I have learned over the years to check the easy and obvious stuff first. You have no idea how much extra work I have done in the past because I was not methodical about troubleshooting.

My plan is to install the new distributor cap tonight. Check to make sure the plug is firing. Install the plug. Run the car, check for vibration at various RPMs, then shut down and pull the plug. If the engine still vibrates then the plug should show signs of fouling. If it does not vibrate then I will run the car for a few days, and then pull the plug to check.

Hope springs eternal. I am irrationally optimistic that the new distributor cap will solve the problem.

knight37128

As badly fouled as that plug is it should be obvious. Turn the motor over with the valve cover off. That valve will open very little (if at all). I would think you don't need the dial indicator.

NEVERL8

Thanks. I will give this a visual look tonight.

67vetteal

Start at the basics! Do a Compression test. Pull all the plugs and do all cylinders. Record your findings in a Log book. If you haven't started one yet start one now. It will save you time and money as well as being a great convenience for future Preventive Maintenance. Consider yourself to be a Detective and take an investigative approach to your problem. Look at the basics. Compression, Fuel and then Ignition. I'm suspect of your rebuild. Even the best re-builders have things go wrong despite a correct assembly. I didn't look at your photos which will be a help with diagnosis but what I have offered will still be valid. Al W.

ghoastrider1

I agree with most things said here except about the float(s). They supply fuel to ALL the cylinders,from the top(inlet) of the manifold.That would foul all.
A bad vavle seal would only smoke at start up AND when under heavy vacum,such as de-accelation from a higher RPM.It would not effect compression reading. Worn cam lobe should be visable to the naked eye when turning over the engine.( i too have been there, done that).The movement will be much less. One possibality,tho i doubt this is the case..is that all ring gaps were lined up instead of being spread around the piston.I have also gotton back,from the machine shop,a piston installed backwards on the rod. Before I started yanking parts,I would try the "leak down" compression test. Number 8 has excellent figures,but how long will it hold it? I also wonder about the valve seal and guide,both being a bit worn. I used to have a motor that went thru rings and ring landing(pistons) like a kid thru candy..but that ws my fault for running lower octane than I should have.

67vetteal

I went back and looked at your JPG.s. Without touch and smell I'd say you have an Oil problem. I once looked at a 327/340 in a 63. Same problem of fouling. Only difference was that motor was loosing coolant. Are you? Turned out that Bubba had Bored the "Original" block .80 over in all cylinders and the #6 went clean through to the water jacket. This was found by a visual inspection. Coolant, (anti freeze), entering a combustion chamber will present the same appearance. Al W.

NEVERL8

Tonight, the easy stuff. Put on a new distributor cap. If the engine vibration goes away I will drive it a bit before pulling the plugs.

After that, log book and a methodical approach to troubleshooting. I am an electrical engineer by trade so I understand very well structured troubleshooting.

Thanks for the input.

Bruce

67L36Driver

Your #8 is sucking a lot of oil and/or coolant from somewhere for it to build up that much crud in a short time.

Primary suspects are the intake gasket, head gasket, cracked head, cracked block and the valve guide seals. If you have the equipment available, do a leak down test. If not, pull the intake and pass side head and look.

NEVERL8

No smoke at start up or heavy deceleration. My wife ( a jr. motorhead) has drive behind the car for many miles and there is no obvious blue or white smoke from the exhaust.

I have the original compression numbers I took last fall. I will find them, review and publish here on the forum.

I do not have a leak down tester but may invest in one if they are not too expensive. I realize the leak down test will give me valuable information not available from a compression test. The car has factory AC so the right side of the engine is very "busy". Taking off the heads means removing a lot of the AC equipment I installed over the winter. This will not be fun to undo so much of the hard work I put into rebuilding the AC system, but if it has to be done then it will.

mudbone64

What affect would a bad ignition coil have? I'm hestitant to respond to this thread because electrical crap has to be my weakest point. However, a few years ago I had a 75' convertible that I kinda "restored" the engine compartment. During the re-assembly I forgot to install the ground strap for the HEI coil and the engine seemed to have dead misses all over the place. After installing the ground strap and a new ignition coil and she purred like a kitten.

NEVERL8

If the other 7 cylinders were not firing perfectly I would consider this. The problem appears to be related to #8 alone. A new spark plug wire and a new distributor cap should put the electrical side to bed.

67vetteal

A Leak Down test is not called for at this point. A standard Comp. test will give you enough info. to begin. Keep the info coming. Al W.