Fouling Plugs

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Mupoo

Mupoo

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Gidday, I'm having a bit of a problem with the 383 fouling all its plugs. It is currently running a factory electronic ignition with an orange box, I have put new leads on it & coil (just a cheap one but), the carb is a 750 vac Holley with size 70 jets & is running a 4 post ballist resistor.
Being that I'm fairly new to this style ignition, is it normal for the plugs to foul fairly easy? I'm thinking of putting a full MSD setup in it if I can't work it out or if this is normal. I haven't had the dizzy out to make sure it is working properly but the rotor & cap are both in good condition.:banghead:

Your comments please!
 
Mupoo said:
Gidday, I'm having a bit of a problem with the 383 fouling all its plugs. It is currently running a factory electronic ignition with an orange box, I have put new leads on it & coil (just a cheap one but), the carb is a 750 vac Holley with size 70 jets & is running a 4 post ballist resistor.
Being that I'm fairly new to this style ignition, is it normal for the plugs to foul fairly easy? I'm thinking of putting a full MSD setup in it if I can't work it out or if this is normal. I haven't had the dizzy out to make sure it is working properly but the rotor & cap are both in good condition.:banghead:

Your comments please!
Click to expand...

What are they fouling with?
Oil?
Grey deposits?

Can you post a picture of one?

Cheap gas causes grey deposit buildup.
 
Initial timing?

fuel pressure?

Camshaft in the engine?

Low initial will get you into all sorts of issues especially at idle.
 
TrailBeast said:
What are they fouling with?
Oil?
Grey deposits?

Can you post a picture of one?

Cheap gas causes grey deposit buildup.
Click to expand...
Don't have a camera with me but they basically look wet & a little carboned, as if it's running way rich. I'm running 98 fuel all the time. From what I have looked up the carb is supposed to be running size 72 jets from factory (Holley 3310-4). I have dropped the plug gap to 0.8mm on this set - havent pull them out to check how they are going yet.
 
crackedback said:
Initial timing?

fuel pressure?

Camshaft in the engine?

Low initial will get you into all sorts of issues especially at idle.
Click to expand...

Timing - I have it set on about 8 deg
Fuel pressure - unsure - have thought of putting a regulator on it just incase.
Camshaft - all I know is that it is a Purple Cam - don't know any spec's.
 
Mupoo said:
Timing - I have it set on about 8 deg
Fuel pressure - unsure - have thought of putting a regulator on it just incase.
Camshaft - all I know is that it is a Purple Cam - don't know any spec's.
Click to expand...

Initial is your first issue.

Set initial at 16 and see if that helps. You'll have to turn the idle speed down when you do it and reset the idle mixture screws. You may and likely will need to alter the mechanical advance to hit your total number. I don't even run stock 318's with 8* initial and you have some type of camshaft in the engine. Bump it up.

Is the float level set properly, no fuel dripping in from the carb boosters?

You have a vacuum gauge, correct?
 
as with everything above, ive seen people run incorrect ballast resistors and internally resisted coils piggybacked with a resistor, basically equates to very low coil output, should be in the neighborhood of 1.3 ohms at the ballast and 1.5ish in the coil itself.....
 
Check carburetor’s power valve for leak. If PV diaphragm is ruptured, that is won’t hold a vacuum when sucked on, power valve is dumping excess fuel causing an over rich condition that will blacken plugs in no time at all throttle openings.
 
The exact thing happened to me and it was a very easy fix. Make sure you have a ground strap from the engine block to the firewall. Electronic ignitions are very sensitive to not having a good ground.
 
The 383 in my 65 Newport fouled the plugs once and stranded me. All it seems to take is a light coating of carbon. Replaced the plugs and fired right up. That was with the original Stromberg 2 bbl carburetor. Can't recall how I fixed it, but I do recall rebuilding the carb once and running on it another 2 years with no similar problems.
 
wjajr said:
Check carburetor’s power valve for leak. If PV diaphragm is ruptured, that is won’t hold a vacuum when sucked on, power valve is dumping excess fuel causing an over rich condition that will blacken plugs in no time at all throttle openings.
Click to expand...

Bingo.
 
As always with every thread about this.

Get the TIMING figured out FIRST!!! Timing ALWAYS affects carb, carb rarely affects timing...

Lots of "carb" issues are really rooted in other systems problems.

Is this thing fouling the plugs while idling? Does it smell like a fuel truck out the exhaust?

Find the maximum initial timing point that the engine will still start when warm, so you know that limit. Unless the cam is REALLY big, 16-20 initial is usually a decent range to run. It takes work to get this right. Lots of people live with sub-standard tune ups because of laziness.
 
crackedback said:
As always with every thread about this.

Get the TIMING figured out FIRST!!! Timing ALWAYS affects carb, carb rarely affects timing...

Lots of "carb" issues are really rooted in other systems problems.

Is this thing fouling the plugs while idling? Does it smell like a fuel truck out the exhaust?

Find the maximum initial timing point that the engine will still start when warm, so you know that limit. Unless the cam is REALLY big, 16-20 initial is usually a decent range to run. It takes work to get this right. Lots of people live with sub-standard tune ups because of laziness.
Click to expand...

I have to agree 100%. This was my problem. No more fouled plugs.

Fred B
 
I'll try the timing & see how she goes.

Just so I can check out the dizzy, what gap should the pickup have?

Thanks Guys
 
If it's a MOPAR distributor, the gap between the pickup and each of the teeth on the reluctor is spec at .008, to be checked with a non magnetic feeler. Lots of folks use a brass one. I use a business card. Someday, I'll have to try to find a brass feeler gauge.

ATB

and HAPPY NEW YEAR

BC
 
64ragtop said:
If it's a MOPAR distributor, the gap between the pickup and each of the teeth on the reluctor is spec at .008, to be checked with a non magnetic feeler. Lots of folks use a brass one. I use a business card. Someday, I'll have to try to find a brass feeler gauge.

ATB

and HAPPY NEW YEAR

BC
Click to expand...
Good one
 
Have limited the mechanical advance & set at 18 deg, reset the reluctor gap, feels good - now to drive it for a while and see how it goes

Thanks Guys
 
Another thing to check for is a Vaccum leak. I was fouling plugs in my crate 360 magum and i went thru hell trying to figure it out, turned out to be a vaccum leak.
Because I had a vaccum leak, my engine wanted more fuel at idle, so i i richend up the idle air mixture screws but it was too much and ruined plugs all the time.
 
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