Looking for some guidance on spark plugs. I'm not a tuner at all but am looking for ways to improve. The motor is 330 ci with worked ECZ-G heads & a Snider cam. Has an Edelbrock duel quad intake with Carter WCFB carbs. Has an old Mallory distributor with a Pertronix kit. I was currently running Autolite 45s gapped at .040mm. The engine tune is okay but has room for improvement. It's wanting to load up & fowl plugs. Would a hotter plug be better? More-less gap? looking for guidance. 

With 330ci, G heads and if the cam is more than a couple steps bigger than stock, the 45 or an equivalent is about what you want.

Check timing, get the curve where you want it.  Try closing the plug gap to see if the situation improves.  Make sure the carburetors are tuned properly.  The easiest way to do this is to install an o2 sensor.  You can figure out a way to do a temporary install for tuning purposes.  This eliminates guess work, and is far more convenient than the old method  of running in various conditions and then checking a plug on the side of the road with a hot engine.  One trip with a friend to take notes and you can get loads of info at once with an o2 sensor.


Lawrenceville, GA

I have your intake/carb combination with no cam and less compression. I use the same plug with a tighter gap. .035”. I would make sure your fuel pump pressure is under 5 psi. Mine is 4. I once tried a one size smaller jet in the primary of the lead carb but went back as it caused some high gear bucking.
I have all 4 floats, 2 on each carb, set to the secondary height which is lower for the primary. All of my plugs are very clean with no coking. I idle on both. Slight choke on rear only just to put it on the higher idle when cold. I also kick it in the butt once a month to flow fuel thru all 8 barrels. Good luck. I’ve always admired your engine and car…JD

56 Vic, B'Ville 200 MPH Club Member, So Cal.

That's a really good idea! 

Your motor was allot of inspiration. Thank you for the tuning tips. We're going to need them. 

I have a 312 with an E4 cam, Summit 600 CFM 4 barrel. I use Autolite 46 plugs gapped at 34 runs great instant acceleration, not an ounce of hesitation. I would also recommend Taylor wires they are amazing. BTW your engine compartment is world class, what car is that.

1955 312 T-Bird Warwick, NY

312yblock… it’s a Black 55 Ranch wagon with CV looking roof and 56 dash. It is “stock” appearing but by no means stock anywhere. It’s drop dead one of the best 50’s Fords in the country.

On the HAMB there is his complete build of the car. Search on HAMB “The Wagon Ford Shoulda’ built, so we did” by Rockets Hot Rod Shop.

I’ve seen it at the AMBR roadster show in Pomona Ca and photos do not do it justice.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

I saw the car a couple weeks ago in Puyallup at Goodguy’s. DLR is right, the pictures come nowhere close to doing it justice. Both the builder and the owner were there, couldn’t ask to meet a couple nicer guys.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

DLR/Miker I checked it out, incredible.

1955 312 T-Bird Warwick, NY

As a general rule, no more than 0.035” plug gap for carbureted engines.  The richer the fuel mixture and/or higher the compression ratio, the less the plug gap.

If the plugs are fouling due to loading up, the Autolite 46’s will delay that to some extent but will not be a cure all.  If the engine has had the compression ratio stepped up beyond stock, then Autolite 45’s would be a better choice.  My thought process says you will need to work on the carbs to get the idle and low rpm fuel mixture leaner.  A reduced manifold vacuum may have the power valves open all the time thus enrichening the fuel mixture to the point of fouling the spark plugs.  A high fuel float level on one or both of the carbs can also be a contributing factor.

Lorena, Texas (South of Waco)