ziekaiser

Ok, I have a 460 in a 94 Crown Vic and it has s skip that, under full acceleration, starts at 4000 rpm's up to 5000. It is fouling the rear drivers spark plug. The engine is new and all cylindes have been checked for compression, not a problem. It has Edelbrock alum. heads. It has a hydraulic cam. It runs 12.60's at 112mph in the quarter on Dayton street tires when it's not skipping. The carb has been eliminated as well as coil, ignition and plug wires. It is not running out of fuel, the factory pump is sufficient but I do have a Holley blue pump in tandem, that is toggle switched. The car runs the same, with or without the pump running. As the block has been decked, I am wondering if if could be sucking air from the valley pan area? It is not leaking where the intake mates to the head. My good friend and the mechanic that put the engine in the car has been a mechanic for over 40 years and he knows what he is doing but this thing has him stumped as well as everyone else. Oh yeah, it is not push rod or lifter related as the intake has been off 4 times checking various things. The cam was degreed and the timing is correct. All valve springs have been checked seated (they too are new) and at 50 thousandths lift. None were weak. Voltage has been checked and is ok. All of the vacuum is on the one runner, so maybe this could be something? The brake booster is good. Any suggestions or help would be appreciated. Steve

BLACKSNAKE427

By Fouling Is It Reading A Fuel Foul Or A Oil Foul?

ziekaiser

It is actually cleaner than the rest. It appears to be leaning out on that cylinder. It is believed that this is because of all of the vacuum crap on that runner. I'm going to block off these things and run it (drive it) and see what this does.

Paul Kane

This could be several things. Start with a cylinder leakdown test (not a compression test). If there is leakage, it will reveal from where. I'd also use a valve spring checker and check open pressure (not just seat or 0.050").

Paul

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ziekaiser

The engine has about 6500 miles on it, all brand new. The car was last running great about two weeks ago. No skip. Then the problem reared it ugly head last Tuesday. This is why the springs and cylinder(s) have been eliminated as a probable cause. Maybe they should not have been eliminated after all. All lifters were removed and checked as well as push rod clearances. Thank you very much for you thoughts

BLACKSNAKE427

Being That It Is Cleaner Than The Rest Of The Sparkplugs And It All Of A Sudden Happened Have You Pressure Checked The Cooling System? Water Introduced Into The Cylinder And Compression And Ignition = Steam Which Could Cause The Plug To Be Cleaner And Skip.

ziekaiser

No, no loss of water, cooling system is fine.

BLACKSNAKE427

Thinking Out Loud. This Is Stumping. Have You Tried Your Previous Mentioned Test By Disconnecting The Vacuum Lines? And Just To Make Sure Your Distributor Cap Point Is Good For That Cylinder? And Your Magnetic Pickup Teeth On The Distributer In Good Shape? This Is A Good Problem And Just Watch It Is Going To Be Something So Simple. I Have To Admit I Am Intriged.

ziekaiser

I'll respond this evening when I have more time. Thank you.

ziekaiser

No I've not yet had the time to even start the car. I was going to take it to my friend/mechanic's on Sunday past and was not able to get it there. Actually he took the whole distributor out and replaced it with another one, known to be good and this did nothing, same problem. As a matter of fact the plug wires and carb were changed as well. We thought that he had actually fixed the problem two weeks ago. It ran GREAT for three days and then messed up again. He ran all "hard" wiring, bypassing everything that went through the firewall and computer. I replaced the new factory coil with a new Excell factory replacement model We thought that there was some issue with the wiring and or computer. This was not the case though. Also it has factory ignition components, except for the aftermarket coil and the factory stuff has been great. In the state of tune the car is, factory stuff is fine. It really is frustrating because I've always had some car that would run well, and have NEVER had any problems. He just got it running and never had to touch it again. Other than checking the timing or something minor. Two other guys in town, in their 60's as well and have had 10 second cars in the 1/4 can't come up with anything either. Oh yea, the harmonic balancer has been checked, he took off the crank pulley, to make sure that it had not turned or spun. He said that he had seen one Ford do this one time and the timing therefore was jacked up who knows how much. I was hoping that that was it. But no. His next plan, as stated before is to see about vacuum issues and maybe change the jets in the carb. I do not think that it is a jetting issue because it ran great before with the jets that came in the carb. He knows not to put too big of jets it the carb. I feel that it is sucking air from the bottomside of the intake, because of the misalignment, caused by machine work, of the heads and intake. YIKES!!!!!! I'm sure that you would have to go all the wat to Mt. Pilot to get that fancy machine work done, if that is it!! Anyway, sorry for the pocket novel,