Only 4 plugs carbon fouled

[butch27]

Lots of good info. Thanks Guys.

[butch27]

I discovered that I have a SPREAD Bore 1" riser  under a SQUARE bore Edelbrock carb I wonder if this would have any affect on the trouble.?

[wayne petty]

I discovered that I have a SPREAD Bore 1" riser  under a SQUARE bore Edelbrock carb I wonder if this would have any affect on the trouble.?

you will find that since you say both sides of  the idle circuit respond and you have cleaned them as described above to blow out any debris from the idle air bleeds.

that either one of the primary rod holders pistons is not free to travel up and down in its bore.. its stuck up and one side of the carb is running rich...

or the high speed air bleeds for one side are clogged as described above..

you can check both with the carb on or off the engine..  i would advise talking it off to reduce the chance of FOD into the engine..

do you have these booklets

http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf

http://www.edelbrock.com/automotive/misc/tech-center/install/1000/1404_manual.pdf

if you have never opened a carburetor... would you like to see some videos on how its done???

   directly from edelbrock.. there are several more to watch also...

[butch27]

Strange thing: I just set my plugs at 44 instead of 35 and the darn thing is running better..

[wayne petty]

Strange thing: I just set my plugs at 44 instead of 35 and the darn thing is running better..

wider gap gives a larger area to ignite the air fuel mixture...

the wider gap forces the coil voltage higher before it can flash across both the cap to rotor gap and the gap at the spark plug creating a hotter spark..

is there a chance your carb is still under warrantee from edelbrock??? where you can call their tech support line and ask them about your issues.. or just call them any way.. they might have you box it up to send it back either to them or to the store you bought it at for a replacement..

i still need to drive down there as its only about 18 miles from here..  they are only about 6 block from SpaceX  as i recall..  and talk to the carb guys there..

or have a professional carb guy  check your carb on his test mule to see what is going on with it.

the only other things could be a  leaking EGR passage.. since you have a dual plane intake.. if one of the egr passage is leaking.. you could have exhaust flow into one side. its unlikely.. but anything is possible at this point..

if you had the spark plugs fouling on just one cylinder head.. it could have been a mis matched set of heads.. small block fords actually used three different sizes of spark plugs..  18 mm spark plugs on the motors up thru 71 or 72... then they went to a 14mm spark plug with a 0.460 reach thread.. but in the last generation in the mid 90s... they went to a 14mm spark plug with a 0.750 reach..  this is a strange change but i can explain it.. they have robots assembling the engines.. and the 3/4 reach holes were counter bored so the first 7/16 was Unthreaded. this made the spark plugs very hard to cross thread for the robots.  2300 pinto/mustang motors went to this partially threaded set up in 84 as that is when the 2300s were assembled only by robots.