Plug fouling

[mustube]

I checked my spark plugs this morning and the spark plug insulator that is usually white is now black, according to the "how to read a spark plug" guide that i have, it says that this is caused by the insulation resistance dropping to 0. Does this sound correct? and how do I fix this? Do I buy new spark plugs? Thanks

 

[rbohm]

8) first determine if the deposits are dry or oily. if dry then you have excess fuel running through. if oily then you have excess oil running through.

 

[CZLN6]

Howdy Back Mustube:

NO, it does not sound right. Are all of the plugs black? How old are the plugs? What heat range? How new are the plug wires? Is this a change since the last time you checked the plugs? When was that?

How is the engine running? Any changes in performance lately?

How many miles/years on the engine? Does it use any oil?

Given your location it is unlikely that you will ever need to use your choke. Is it set lean?

Keep the info comming and we'll get this figured out.

Adios, David

 

[mustube]

Howdy Back Mustube:

NO, it does not sound right. 1.Are all of the plugs black? 2.How old are the plugs? 3.What heat range? 4.How new are the plug wires? 5.Is this a change since the last time you checked the plugs? 6.When was that?

7.How is the engine running? 8.Any changes in performance lately?

9.How many miles/years on the engine? 10.Does it use any oil?

Given your location it is unlikely that you will ever need to use your choke. 11.Is it set lean?

Keep the info comming and we'll get this figured out.

Adios, David

1.yes all of the plugs are black
2.I have no idea how old the plugs are, they were on the car when we bought it and it has been at my grandpas farm and i just brought it home a few weeks ago.
3.i have no idea, how do i check/how would i know?
4.same as the plugs, they were on the car when i bought it
5.havent checked the plugs before
6.this was the first time
7.the engine runs DECENT when warmed up well, you have to keep on the gas for about 30 seconds when you first start it up to keep it running, if you dont the engine will die, it sounds like its missing a little when in idle but that seems to go away at higher rpms
8.its been like this since ive bought it this is just the first time ive had the car in front of me to fix the problem
9.the engine has been rebuilt one time before but do not know when that was, the car shows 68,xxx but im pretty darn sure that its rolled over at least if not twice.
10.it doesnt use any oil
11.it is set to where it idles the best but it is rich i think (whichever has more gas).

 

[ludwig]

David's going to tell you to get new plugs and wires. Wire is a misnomer. It is a flexible carbon shaft in an insulating jacket. This will degenerate over time and through use. You have both conditions. Old and high use.

Get a set of plugs that is right for your engine. The dealer will have the number. Get a good set of plug wires. The whole deal will cost about 35-40 dollars. The best part is that the plugs come separate or in sets of 8. So if you buy them in sets, every third plug change, you get a new set free.

Once you have the new plugs and wires, check the plugs for a base line reading. Then run it some more and check again to see if anything changes and how they look then. With a good strong spark, the engine starts better and ignition improves. You can improve it even more with an electronic ignition: Pertronix, DS II, DUI.

If it is too rich, you can often smell gas in the exhuast. At the very least, you should have a vaccuum guage. Once the engine is running and warmed up, hook the vac guage up close to the carburetor and adjust the fuel mix until you get the highest vacuum. Should be over 18 lbs. Turn the screw in until the engine starts to stumble, then back it out until the vaccuum peaks. Then back it off just a touch more; no more than a quarter turn. That will be a good mix. Too lean and it runs hot. To rich and you extinguish the spark.

 

[mustube]

I was thinking of going with DSII ignition and am doing research on that right now. I'll go get new plugs and wires tonight and see if anything changes.

 

[mustube]

OK I just put in new Autolite spark plugs with 46 on the side (the ones recomended by the parts store and the same ones that were in there before. I started it up and now you dont have to stay on the gas but for 4 or 5 seconds. But it still sounds like its missing somewhere.

EDIT: I gapped the plugs at .035 I read that to be a good gap for stock system, they came gapped at .045.

 

[Stubby]

I just finished fighting a similar problem.

The engine I fought was a 68. It had a non scv 1100 carb and was extremely rich. I tried everything I normaly do. Tear down clean, find what don't belong in the picture and fix it. The carb appeared to be a rebuilt unit. After opening it up several times, I broke down and installed the LM1 AFR meter. The AFR was 13.5 at idle and 9.2 everywhere else. Off idle, cruise, wide open, It didn't matter what you did with the throttle, the AFR was average 9.2. I suspected the power valve was staying open. It had a lot of slop in it and was kinda sticky. I noticed that the carb top was warped from over tightening of screws. I don't think this was the problem, but it was a good excuse to experament and observe. I closed the power valve and permanantly seated it. I made a run down the road and the AFR improved to 10.1. I then installed a 65 SCV carb and ran it down the road. 12.2 to 12.5 AFR, and it sounded so much better.
After reading some post today, I looked at the jet in the 68 carb. It had a 69 That is the problem with most rebuilt carbs, you have no idea what you will get.

To sum it up. If you don't know the history of the carb, search, compare and don't asume.

The first tank of gas in the 65, it got 11 MPG I feel it is close enough to start playing with the DSII and then I will tune on it some more.

 

[69.5Mav]

Don't neglect the distributor. chances are that the cap, rotor and points are as old as the rest of the ignition parts (plugs and wires). Get a new distributor cap, rotor, points and condensor. Then use a plug attached to a spark plug wire to check the actual spark, it should be big and blue and make a load chack noise, if not then you may need a new coil as well, check your timing and note where it is set and adjust if required. Once you get the ignition system squared away you can look to the carb for futher adjustments.

 

[CZLN6]

Howdy Back Mustube and all:

You've got some really good advice and thoughts. But, first things first. On the plug gap, .035" is a good place to start. Take a drive for 20 miles or so with little or no idling. Check the spark plugs for color and wetness. Note. Next, simply let the engine idle for 5 minutes or so. Check the plugs again. To simplify check plugs #1 & #3. note any change from 1st reading and report back here.

Next, check the initial timing setting. I don't recall you saying what year or trans your car is, but set the initial to stock specs to start with. While you're at it check the vacuum hose from the carb to the vacuum cannister on the distributor for any cracks or leaks. In addition to a visual check, listen carefully or any hissing or sucking sounds. They are an indication of a vacuum leak. A piece of hose used as a stephascope can help in locating the leak. Fix any leaks.

Next check your automatic choke on start up. Remove the air cleaner and start the engine cold. The automatic choke will be set by depressing the throttle. As it warms, watch the choke open. You may have to hand flick the throttle linkage for it to open. It should open completely in 5 minutes or so. If it does not, adjust by loosening the three screws on the side of the black choke spring housing and turn the black housing til the choke plate is vertical.

While you're on the carb it would be a good idea to spray down the outside and inside with a good carb spray cleaner. Next, look down (engine off) the carb as you work the linkage. You should see a squirt of gas as you open the throttle. If you don't, the accelerator pump is weak. That means it is time for a carb rebuild. The rebuild kit will also have a new power valve in it.

A can or two of fuel system cleaner through the next couple of tanks of gas is a good idea too.

Stubby- FYI, Your '68 1100 has a 1.1 venturi and is rated at 150 cfm. The 65 1100 has a 1.2 venturi and is rated at 185 cfm. In addition to a better A/F ratio you gained some performance potential too.

What jet size was in the '65 carb? It still is rich in the 12:1 range- but way better.

Adios, David

 

[Stubby]

I didn't actualy look at the jet size. I was preocupied with finding the problem (like maybe a 1/4" hole in the carb allowing fuel to drain straight in the engine ) I figured the stock jetting would be close on a stock engine. Key word being ASSUMED!!! It is close enough to tweak on now.

Did I mention that I love my LM1. 8) It's nice to have a good measuring stick.

 

[mustube]

Ok i ran the engine again after getting new plugs and wires, and the plugs are brown with a slight wetness on the end of the insulator. The engine still has a miss or something going on and there aren't any vacume leaks that i could find. The choke opens all the way when warm. I am going to wait until the end of the week to get new points, rotor, cap, and condenser until the end of the week, I am going to the salvage yard to look for a 5-lug donor, if I dont find one I am going to convert it to electronic ignition with either a GM module or orange chrysler box.
The engine and trans are stock 1966 Mustang.