What's the hottest sparkplug you've used on a 440???

[kiwigtx]

I've been having plug fouling issues of late when idling for long periods of time. It became really noticeable during the recent Beach cruises, where cars clogged the streets, and traffic came to a standstill.
Currently using NGK BP5S plugs, and I have had most success with those over the years. But i wondered if a hotter plug would help me cure the fouling without hurting the engine at higher constant RPM's.....any thoughts? :thinker: The A/F ratio was checked recently and found to be around 13.5-14.5 at idle and through the RPM range on a QuickFuel 780 V/Sec

Specs; 95 Octane gas, 10:1 compression, Edelbrock dual plane 2191, TTI 1-7/8" headers, timing spot on, MSD Blaster II coil, 8mm leads, operating at sea level.

Couple of pics of No.8 plug;

The fouling cleared after about 15 miles at 50-60mph, and of course hitting the higher numbers on the flat roads cleared the remaining carbon buildup. :headbang:

 

[Stewsta]

Did you have to do much tuning besides idle air screws with your 780QFT. I just put a new one on out of the box and I'm having trouble with fouling plugs as well.

 

[kiwigtx]

I have had the QF rebuilt once, and cleaned out last week also. I changed out the idle air bleeds from the factory "70" to a set of "45", which made a big difference in idle to 1100 bogging/stumbling. Only changed the fronts, so may be looking at the rear bowl this weekend. Also changed out the main jets but don't have the figures right at hand now. But on the whole ran well out of the box.

 

[miller]

Had the same kinda fouling prob on the last 383 hipo I built. Once every month I'd have to clean the plugs because of fouling. New motor, and parts and pieces.

It was my plug wires. New and improved. Getting low spark at low, or idle speeds.

Understand, I was running standard ignition (duel point), but built a set of stainless steel wires. That's aircraft plug wiring...prob fixed.

Check your spark.

 

[Meep-Meep]

If you are running a high overlap cam this can be the issue. Lot's of mixture dilution going on at low speeds, which means the engine just won't like running at low speeds for extended periods of time. My old 383 back in the 80's had a hot Isky cam on a 108 LSA, and while it made great power in the upper mid range, every now and then a plug (or several) would crap out and I'd be shooting ducks at 4000 RPM. Change the plugs and problem solved. This is why for a true street driven car I recommend a wider LSA cam (lower overlap).

 

[GTX MATT]

Those plugs look wet/oily, is this a well used engine?

 

[kiwigtx]

Those plugs look wet/oily, is this a well used engine?

No, engine is fine...this was No.8 plug, and the valve cover gasket has a tiny leak above. :head_smack:

 

[Cranky]

Timing is spot on according to what? Book stock?

 

[Badvert65]

As far as plugs go....I have been using Autolite 86 after much experimentation (with plugs) in the 80's when I first started racing. I have occasional carb issues with the two 4 bbl tunnel ram setup (when it sits a long time) but usually this will burn off. For severely fouled plugs, I just replace them, easier and simpler than trying to clean them.
I like the 86's, they have been very good in my 440's.