Why am I burning up spark plugs so quickly?

[sdkar]

Hey guys,

I have a brand new crate motor from GM.  I have the 502 deluxe, which comes with everything, including the Holley 870cfm carb.  I installed the engine and it ran great.  The car is not on the road yet and pretty much gets started just to go in and out of the garage.  I am on my 5th set of spark plugs.  I install the new plugs and the car starts up right away with no problem.  After a few times starting, it starts to run rough and sputter.  Eventually, the car will stall and will not start back up at all.  No matter whay I try...it just turns over and nothing.  It does not even try to start.  I install a new set of plugs and it fires right up and runs perfectly.  No sputter or hesitation and runs like the timing and everything is perfect.  Only to repeat the process all over again.  I have even tried installing a new set of plugs and letting it run for 20 minutes to get the plugs warmed up properly.  This does not help.  I pull the plugs and the white part around the tip is black.  Cleaning does not help at all as I have tried cleaning them with lacquer thinner and/or a wire wheel where the black is all gone and then re-installing them and still no start.  Everything it brand new.  I have the fuel pressure set at about 7 psi.  The power valves are good and I believe the floats are set correctly.  I set the idle/fuel mixure screws in at about 1-1/2 turns out from seating.  I then started the car and turned each one in until the engine dropped in RPM and then turned the screw out 1/2 a turn and left it.  What could be the problem.?  What do I need to check?  Did I do anything incorrectly?  This car is ready for road testing but I can't get it to run for more than 20 minutes before the plugs "foul" again.  I am tired of buying 8 new plugs everytime I foul them up.  I have 5 sets of spark plugs with 20 minutes on them.  Is there a correct way to clean them so they will work again?

Any and all help is greatly appreciated.  The engine is under GM's 3 year/100k warranty, which includes the Holley.  However, I would still have to have the car towed in to the dealership and then allow some mechanic who has probably only worked on fuel injection systems and does not know what a carb is wok on it.  Then I will be told that the problem is not covered by the warranty as it was a setting or timing problem or a problem caused by something other than the motor (such as the electric fuel pump or regulator) and that I will have to pay them to figure out the problem.  And we all know how inexpensive the dealership service shop is.  I have purchased a couple of Holley tuning books as well as read every article online and I am almost sure I have set the fuel system up correctly.  There is spark to the plugs, so ignitition is not the problem.  I am getting fuel no problem as well. 

I am ready to shoot myself.  I will entertain any and all ideas, no matter how crazy they are as I am desparate.  What is wrong and what do I need to do?  Ultimate praise to whoever can come up with a solution that will work. 

Thanks,

Steve
sdkar@bellsouth.net

[JohnZ]

I set the idle/fuel mixure screws in at about 1-1/2 turns out from seating.  I then started the car and turned each one in until the engine dropped in RPM and then turned the screw out 1/2 a turn and left it. 

Sounds like your idle mixture is way rich. Put a vacuum gauge on it and adjust the idle mixture screws for highest steady vacuum; if it doesn't respond to idle mixture screw adjustment, the throttle plates are open too far and it's idling on the transfer slot instead of the idle system.

[sdkar]

Hello,

Thanks for the info.  However, I am at a loss as to what to do exactly.  I don't have a vacuum gauge, but I will buy one.  Is there a certain type or kind to get?  Also, where do I put the vacuum gauge to get a good reading.  Is there an optimal setting number?  Sorry to ask what seems like stupid questions, but I do not know what to do.  Can you explain it in better detail for me?

Also, if the throttle plates are are open too far, what needs to be done?

Thank you for your help and time.

Steve

[blownonfuel]

I'll try to help Steve. Always start with the basics. I assume the timing is okay. Does the engine get to operating temperature? I would remove the sight plugs on the float bowls and turn on the fuel pump (engine off), check the bowl level. Also with the engine off and fuel pump on check to see if there is any fuel dribbling out of the venturi boosters in the carb., if there is the float level is either too high or there is something in the needle and seat in the float bowl that is not allowing the float to shut off the fuel and it is flooding out. It sounds like you are getting a good vacuum signal to your carb if you are seeing changes in the idle mixture screw adjustment. Just a thought but is the choke plate completely open on the carb? With the engine on use a mirror to look down into the carb and see if there is fuel dribbling out of the venturi boosters at idle, there should not be. They do sell a mini sandblaster just for plug cleaning, some part stores carry them.

http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_13249_13249

[sdkar]

I can put the plugs on a wire wheel and clean them up where they look new again...but when I re-install them, the car still does not run and it is as if I did nothing to the plugs and they are still fouled.  Will the sand blaster clean them better or differently to the point where they will be as new?

I will report on my carb findings after I run through all of the recommendations above.  Also, gas sat in the carb a little too long and I got "varnish" or whatever that dried crusty gas is.  I bought a rebuild kit and carb cleaner.  I then took the carb bowls off and cleaned them up, replaced the power valves and the needle & seats.  Is it possible this "srusty" gas may have blocked a passage way or something?  Where do I look and what do I look for if I have dried gas in the carb?  The carb did not sit that long, but obviously, it was enough to get that dried "varnish".  When I first started out with this problem, I could smell that turpentine-like smell immediately.  Since I have cleaned it up and replaced the components, I no longer get that odd smell, but I am still fouling the plugs.

Again, thank you all for your time and input.  I have bought two Holley books and researched all kinds of stuff on the internet and the suggestions you guys are giving me can not be found on either one and your help is way more informative.

Will keep you posted.

Steve

[blownonfuel]

Steve, a wire wheel is not good for cleaning plugs. The base of the center porcelain cannot be reached with a wire wheel, the plugs will continue to short out (fouled plug). The plug sand blaster does a much better job since it can get down to the base of the center electrode  porcelain. If you do get one and clean your plugs with it make sure to use carb cleaner and compressed air and ensure that you get any sand out of the plug after the cleaning.

It is possible that some varnish may have plugged some of the air bleed circuits. Before you tear into the carb again first check the float levels as suggested. If the levels are okay, check to see if there is fuel dribbling out of the venturis with the engine off and on, remember to use a mirror if the engine is running. You don't want a backfire while looking down the carb., please use a mirror. If all this looks okay we'll move on to the next step.

[dutch]

    My input here is (for the little it is worth) is that it sounds like you are in a dead rich situation and that maybe your fuel presure is a bit too high for a Holley carb. Even if you find the float level(s) are correct 7 PSI may be too much for the needle and seat to handle. It seems to be certainly at or above the upper end of what is reccomended from what I recall for a Holley -  5-6 being the norm from my own experience works better with flow (volume) being more important than the pressure itself...
   Other than that, were the power valve(s) you have the normal 6.5's usually installed? If your manifold vacuum is above 10 then 6.5's should work OK as that is as far as I know, the standard rating usually installed and any further changes should be to install a power valve that is rated 4 inches or so below the actual vacuum measured ie: 10 inches of manifold vacuum should use a 6.5 and no higher or it will open much too soon and run way too rich.

    I can't help but think that you have a blown power valve already installed and maybe a backfire or just poor quality control issue has gotten you to a point where you are trying to deal with the effects of such a problem. Does the exhaust smell overly rich when you install new plugs and actually get it running? - if so it is almost definately a power valve, float level /pressure to the carb issue, or shooter adjustment that is overly tight and leaking fuel directly at idle  - Randy.

[Charley]

How old is the gas in the gas tank ?

[maroman]

How old is the gas in the gas tank ?

Bingo! That's what I was thinking, I've had gas smell like crap in just a few weeks.

[JoeC]

Are you sure you are using the correct spark plug? Sounds like the heat range is too cold.

Maybe a hotter plug will help but you need to check if it is ok to run that heat range

[sdkar]

The engine came with AC Delco Rapidfire #4 plugs.  The local parts store does not have these in stock, but I was told that the Autolite #63 was the same plug.  How do I verify if what I was told is true?

[Adz28]

Since you were looking for "any and all" suggestions... Any chance that beast of an engine needs to be put under load? Maybe the set-up is simply not meant to idle or simply go in/out of the garage. Could a hotter plug and different mixture settings be a temporary fix untill you get it on the road?

[jdv69z]

Sounds like the mixture is too rich to me as well. Don't drag race cars waiting in staging have this issue because the are jetted rich for the actual race conditions which is way too rich for idling?

Jimmy V.

[Adz28]

Someone on the Chevy Hi Performance forum had a similar problem in January. Post a reply and see if they fixed it:

http://forums.chevyhiperformance.com/70/6526402/general-chevy-technical-discussion/chevy-zz-502-problems/index.html

From the Post:
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Does anyone know the correct spark plug for the Crate ZZ502/502 we are trying to get an intital start up to set timing and keep fouling plugs. It has a Vertex Distributor, Taylor solid core plug wires, Holley 850 Street Avenger w/elec choke. We are currently using AC Delco Rapidfire #4 plugs and fuel pressure runs at 6.5. We have problems with loading up quick and wet fouling plugs.

Reply:
during this wetting startup did you block the choke open?? it is usually needed to block things open till you get everything ajusted....
if the choke does not pull off of its fully closed position it will wet the plugs...
normaly the choke will pull open about 3/16 of an inch at the top and it will be up on fast idle step 2 or so....
i personally don't know what the pick up coil and reluctor look like in a vertex dizzy.. but on every other dizzy i  set the crank to the initial timing i want.. and then line up the reluctor and pick up coil  tips... then i lock the dizzy down.. it gets me within a few degrees for startup... so there is no high voltage dizzy twisting to get it to run.....