The one plug almost looks like water intrusion. Have you checked to see if all your intake bolts are tight? Bad intake gasket could draw oil from the valley and water from passage???? How long have you had the engine before these problems? If your throttle blades are to far open there will be vacuum from the ported side at idle.
I think I confused everyone on my explanation of my timing. I have a 30 degree mark on the balancer, with my wife holding the engine at 3000 rpm the 30 degree mark is set at 6 degree on the degree scale. So I am 36 degrees total timing. My idle is set at 800, I will check the idle mixture today. After changing the oil and the new plugs how much running time would I need to read the plugs to see if the A/F ratio is still rich. Can anyone tell the the heat range of an ACDelco Rapidfire 13907139 and the difference between a 13907138 Thanks
The MSD will shoot lightning bolts if you hold wire 1/2 inch from ground. Problem could be coil. I would get rid of those plugs and put in a more correct one those "J" straps are bent down. I would use the plug that takes a .045 gap not one that needs a .060 gap. This is a lot for a coil to jump gap if you are using a points distributor. Definitely Change that Oil! You have clean plugs and fouled plugs could be valve seals wore out came loose. Carb leaking gas when engine off going to those cylinders? If that carb was not built by one of the Q-Jet guru's here then it is junk.
Getting information from you is like pulling teeth. With any Quadrajet, initial ignition timing is very important. The primary side of the Q-jet is very efficient, so efficient that it is very easy to start fuel flow from the main nozzles if the throttle is open too much at idle. The result is the engine running on the main circuit INSTEAD of on the idle system of the carburetor. This (nozzle drip) can make for a very rich idle, and could foul your plugs. If you increase the initial timing, you can close the throttle so this does not happen. I asked you many posts ago what ignition you were running. Then I see in someone else's post, that you are running an MSD Pro billet distributor. All MSD distributors feature an adjustable mechanical advance. The mechanical advance uses color coded bushings that limit the mechanical advance to different degree amounts. https://www.jegs.com/InstallationInstructions/100/121/121-8464.pdf I would use the blue (21*) or the black (18*) bushing so that you can run 12* or more of initial timing. This will enable you to turn the idle speed screw out and close the throttle so the carburetor runs on the idle system. You should be able to turn the idle mix screws in and kill the engine. If you can't, you have the problem I described above. Spark plugs, looks like you are running a platinum plug. IMO, that is a bad choice. No platinum or Iridium plugs for our engines. Use a conventional copper plug. Gap it at .045" The NGK UR-4, or AC Delco R45TS. If you want a cooler plug, run NGK UR-5 or R43TS.
I never use rapid fire plugs. I use 1 colder than factory recommends. If it’s an RT 45S. I use RT 44S. What did you do to the distributor when you installed it? Did you change the springs or bushing? I recommend the black bushing and mid springs. Glad to see you are setting by total timing. Make sure all your connections are tight. I believe a 45 gap is recommended from msd. What coil are you using. I know there have been some issues. Start mixture screws 1 1/2 turns out. Make sure all bolts are snug. only carburetor rebuilder and diagnostic man I recommend is Rob Ross. You can contact him thru here. I hope you get your car right. Keep us updated.
Larry, I do not think I am withholding information or being difficult to obtain information from. On Tuesday at 9:57 you asked about my ignition and at 10:33 I responded "MSD pro billet. The fouled plugs are Autolite 665, I replaced those with a AC/Delco Rapid Fire 19307139. The plugs cross reference with each other." I did respond and I did provide the information requested to the best of my ability. I told you upfront I did not know much about this. I appreciate your help but I do need a little patience with my responses. Thanks for your understanding. An additional point, I am having surgery tomorrow to remove a steel sliver in my finger so working on my car is going to be on the back burner for a week or so. OK lets get back to the original build and set up of this engine. It was built by Mike Phillips of AMP so I am confident the build and initial set up was proper. SMI did the carb, it stumbled on the dyno but ran well, 409.7 hp and 514.8 torque. We decided to install the engine in the car and see if it stumbled on WOT in the car it did. Sean had me adjust the air valve both directions but that did not fix the stumble. The carb was sent back to SMI, they tweaked it, I put it back on and the car ran well. The carb has always lost its prime when it sits for a few days. It requires cranking the engine over and a few pups on the accelerator to start. Thanks all for your help I will be back once my finger is healed and get this figured out. Jim
Did you do anything to your distributor or is it out of the box? Who dialed it in? Did you install it after the dyno? Do you have an electric pusher pump? Is the choke set up?
Sorry Jim, I must have missed post #27. I had asked twice about your ignition, and thought I wasn't getting an answer. Was the MSD distributor set up by AM&P? Seems strange they would have set it up with only 6* of initial timing. It needs more than that. Are you sure about your ignition timing? There is a lot of oil on your spark plug threads, do you have leaky valve covers?
Larry, no problem I appreciate your help. We are not understanding each other on the timing. My harmonic balancer has a 30 degree mark and it is the 30 degree mark I set to 6 degrees on the degree tab at 3000 rpm. I think I am setting total timing not initial timing. If I recall correctly Mike set the mechanical advance to be completely in around 2500 rpm. I do not believe the degree tab on my car goes to 12 degree. I will check today if my finger stops throbbing, if you get a foreign body in your finger don't wait like I did the cure is much worse 90 days later. Thanks again Jim
I understand you have 36* of total timing. My question is what timing does it idle at? Yeah, you really have to be careful about infection. Ask Jim Weise about that.
Jim, as others have said keep an eye for infection on that finger. I went through several operations, couple of weeks in the hospital and a month of intravenous antibiotics but I got to keep my finger. Only lost the corner of it. Well wishes Nelson
