I have a 66 Vette 350 cu.in. and decided to go to a popular car show. The lines of cars exiting was so long the car idled for about 15 minutes before I got up to road speed. By that time the car was running rough and it took several miles and a bit of "punching it" before it ran smoothly again. I am running R45's and tried R43's to prevent this fouling problem but that didn't help. The fouling also occurs when the car is cold and the choke comes in to play. Should I decrease the richness with the idle mixture screws? -- increase the idle from 800 to 100 rpm? -- try a platinum Bosch plug with 4 elecrtodes I see advertised (if they are available) -- try a new coil??? Anyone had this problem -- I heard it can be a problem with the motors intended for "high performance" use. Thanks in Advance Bill
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Re: Fouling Plugs
Bill, pull your plugs and keep them in order of what cylinder. What do they look like, how many miles do you have on these plugs,do you get on it often to keep the engine from loading up,what type of intake filter do you use, carb type,exhaust system, ignition timing etc. Let us know what your plugs look like and how many miles approx on them. I can't trouble shoot unless I know your driving habbits. Also what HP engine, stick or auto, and rear end ratio.Does the car heat up while idling around like that? Good luck,grr#33570 -
Re: Fouling Plugs
Best bet is to rejet the carburetor to decrease the richness of the mix. Fooling with idle adj screws only varies the QUANTITY of idle fuel/air, not the QUALITY. High performance engines are tuned for WOT operation, not the street; therefore they are always rich. Make sure the choke works properly. Are your plugs sooty black? If so, she's too rich.
Varooom!
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Re: Fouling Plugs ALL the Info.
Here is all the information on the 66 -- 350H.P. 327. The plugs are new with 300 miles on them and the insulators are a light tan in color. The fouling only occurs after LONG idles or a "cold weather" start. The engine does not overheat. Intake filter is stock paper pleat and carb is the original Holley. Timing is at a stock 12 degrees advance and I use a lead substitute by Redline of 1 oz. per 10 gallons of 93 octane HESS unleaded gas. I do notice a little puddle of gas on the intake manifold below the carb the same color as the lead substitute. This puddle occurs after the car has been run and sits overnite. Thanks BillComment
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Re: Fouling Plugs
The AC heat range 3 is way too cold for the street. I used AC 43s when I ran my '63 SHP at the track. The AC 45 is best for the street. Buy a set of AC 45s (not R45s) or equivalent non-resistor plugs and set the idle mixture IAW the service manual procedure. Tuning the idle screws DOES richen to lean the mixture. Fouling the plugs on the high performance small blocks is part of the deal esspecially with the single point ignition, which is marginal on reserve ignition energy, and using resistor pulbs make lessens the energy available at the plug.
One other hint: High performance 327s need regular "Italian Tuneups".
DukeComment
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Re: Fouling Plugs
Sorry Duke, I was talkin AFB carbs on the idle mix point. On AFB's the idle jet is fixed at the end of the emulsifier tube on the primary tower and can't be changed. The idle mix screws vary only the AMOUNT of mix into the primaries. Hell, What's a Holly anyway, a packaged leak?
Varooom!
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Re: Fouling Plugs
Hey, as an after thought, Accel makes a plug with the same heat range as a Champion J12Y and I've had very good luck with them in 461X heads.
Varooom!
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Re: Fouling Plugs
Agree with Duke. Do the easiest and most logical things first. Hows the fuel bowl levels also?. But do what Duke suggested. He was thinking right up my alley on that.grr#33570Comment
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Re: Fouling Plugs ALL the Info.
your holley could have a warped metering body or a warped base plate, these will cause rich condition at idle. you should check for warpage on these parts and of course the metering body can be straighten and the base plate will have to be machined to get it back to flat.Comment
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Re: Fouling Plugs ALL the Info.
Bill,
The puddled gas in the intake maniofold is not normal, and you won't be able to stop fouling plugs until you resolve that problem, but that is not your worst problem. IMO, the most significant problem with this fuel leak is that some of that gasoline that gets into the intake manifold leaks past the valves and washes down the cylinder walls, and eventually dilutes your oil with obviously negative results. As already stated, this fuel leak is most likely due to the warped metering plates/blocks that Holley's are infamous for.
I didn't know of this common Holley problem when I purchased my '69 tri-power three years ago and lost a whole summer to fighting it. With all three carbs leaking into the intake manifold on my car, I couldn't get more than a few starts or a couple hundred miles between fouled plugs. I finally got on the right track only after the oil smelled like gasoline.
I solved my problem by purchasing new replacement carbs. The other option is to send them out for repair to someone who knows Holley's and can correct the warpage, unlike the guy that built my 3 carbs that one summer (name withheld). The guy I hear the most praise about with respect to Holley's is Jerry Luck, although I have no personal experience with his work. I'm sure his phone number is in the archives many times. Good luck.
JoeComment
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