FE Plug recommendations

zimmy · #1 (**permalink**) 04-08-2002, 06:55 AM

I am interested in people's opinions about spark plugs for an 427 FE with Weber IDA carbs. I read in the Shelby American magazine that the 427 was recommended to use the BF #32 plugs. I was wondering if that were still the case today and with using Webers. Somewhere I was recommended to use #42 plugs but these may be too hot a plug based upon the recommendation. What say ye, mighty forum readers??

Geary L. Sarno · #2 (**permalink**) 04-08-2002, 09:20 AM

I'm running BF42's on my FE (street use) with success.
Twin Edelbrock 600's - 9.75:1 Compression

-Geary

Toivo · #3 (**permalink**) 04-08-2002, 04:25 PM

It depends a lot on your compression ratio. Avoid Platinum plugs if you're running 10:1 or greater.

JMO

zimmy · #4 (**permalink**) 04-08-2002, 05:13 PM

I am pretty sure that I am running 9.5:1 compression ratio.

Zimmy

SCOBRAC · #5 (**permalink**) 04-13-2002, 12:16 PM

Zimmy,

This I actually can help you with.. All FE motors can run 32's all can run 42's. or even 43's (which I am running now) If I were running long endurance races, for I would say 32's If I were doing a good deal of highway driving I would say 42's I tend to drive from stop light to stop light seldom over no more than 30 min. between starting and stopping. Summer is coming and I am likely going to consider 42's depending on whether or not I get run-on as the outside temp rises. You might want to start with a 42 and see.

Dr. Christopher Jacobs, PH.D., E.E. generally reccomends one step colder than stock for modified street engines, two steps for heavlly modified (11.0:1 compression) and three steps for the race applications discussed earlier.

It is best to use a copper plug of conventional design for use with an MSD. Exotic plugs work well in OEM applications with a marginal output, but tend to restrict the potential of a high performance CD ignition, and even reduce top end power.

I found with 10.5:1 compression .040-.042" gap worked best (for me). Standard gap out of the box is .035. MSD guidelines say .035-.055 depending on compression.. 11.5:1+ being .035 and 9.0:1 being close to max at .050-.055

Good Luck,

zimmy · #6 (**permalink**) 04-13-2002, 06:23 PM

Michael:

Thanks very much for the information. I will probably try the 42's to see if they are better. Right now I have been running with 45's but I think I'll go down one. I do use the MSD 6AL and set the gap at about .045". Seems to work well. Thanks again. Always looking for as much opinion or fact on car things as I can get.

Corey

PS Any opinions about plug wires. I am currently using MSD Super Conductors but may change them for a dumb reason. They are 8.5mm and a lot of the looms and holders to try to neaten up the compartment only hold up to 8mm. Still just thinking about it.

SCOBRAC · #7 (**permalink**) 04-14-2002, 07:28 AM

I use the taylor 8mm and the taylor holders look pretty cool. They come in red blue and yellow. I have a photo in my pict gallery.

Steve Jones · #8 (**permalink**) 04-17-2002, 06:52 AM

Is anyone using non-resistor plugs?
I've always had a plug fouling problem. I even went to the trouble of installing an O2 sensor and monitor to help get the carb jetting correct. Finally have come to the realization that when it comes to Holley Double Pumpers & street use, you can't get there from here!!!
Anyway, back to the original question, does it make any sense to use a high output ignition system and then install resistor plugs? I don't have a radio, so I don't care about RF interference (couldn't hear it over the sidepipes anyway

). If you go to a parts store like NAPA or PepBoys and ask for non-resistor plugs they look at you like you just stepped out of a flying saucer.

What to the serious racers use? Surely not resistor plugs, and if not, where do they buy them.

Geary & Zimmy
What brand are BF 42's & 43's? Are these Autolight #'s? Are they non-resistor and if so, where can we find them? Please be more specific.
I've tried Champion RC12YC (recommended plug for the Edlebrock heads) and Autolite 3924. The Autolite's seem to be marginally better, but will still foul on occasion. My thinking (and it may be flawed) is that a hotter, non-resistor plug might be less likely to foul. I'd sure like to find something better.

Steve

jwoodard · #9 (**permalink**) 04-17-2002, 06:27 PM

I'm running Accel 416's in my FE. These are the plugs George Anderson recommends and I'm having good success with them. I run the MSD 6AL and have the plugs gapped at .043".

Jim

SCOBRAC · #10 (**permalink**) 04-19-2002, 08:36 PM

Steve,

You didn't mention which ignition you are using.. The RC12YC is a washer type plug (verses compression fit) What is your gap?? try lessening it.. We are referring to Autolite OEM style FE plugs.

I run 900 cfm (two 450's) rejetted and squirting at least as much as any double pumper without a hint of fouling.. What type of fouling are you having??? Color, texture, smell??? Heat and resistance are very different. Resistor plugs are not "cooler" than non resistor plugs.. Just different. Race plugs are much cooler by nature, 3 steps typically, and would be more prone to foul in a non race environment.

Steve Jones · #11 (**permalink**) 04-23-2002, 06:33 AM

Michael,

I'm running the Mallory HiFire IV ignition with a Mallory Promaster coil and Unilite Distributer. I'm also using Edlebrock heads and that is why there is a difference in the plug style. The RC12YC Champions are what Edlebrock recommends and the Autolite 3924 is a slightly hotter replacement for the RC12YC. These are both resistor plugs though, and since I don't have to worry about RF interference I'd like to try non-resistor plugs. I'd just like to be generating the best (stongest) spark possible and hopefully fire through fouling that might otherwise cause a misfire.
The fouling I've experienced is definitely caused by a "rich" fuel condition (moist black & sooty). I've gone the whole nine yards with vacuum tuning the idle & power valve circuits while also monitoring the mixture through the oxygen sensor.
Got it close but not perfect.

Steve

SCOBRAC · #12 (**permalink**) 04-23-2002, 05:12 PM

Steve,

That is a "modern" plug with the assumption that a vehicle running the plug has electronic devices that would be interfered with (not just a radio) e.g. computers, et al. I know of no replacement that is not a resistor plug, although I do not think that a non resistor plug would be of any advantage.

I would look toward carb jetting to be honest with you. if your plugs are wet you are either having partial ignition failure or a super rich condition. What carb(s) are you using? What jets? Also what is your normal operating temp? Are you using a thermostat? which one? My 428 will not run (well) below 175-180. If you are using a 160 thermostat you may not be developing sufficient temp to vaporize ALL the fuel you are trying to burn..

Hope this helps..

SCOBRAC · #13 (**permalink**) 04-23-2002, 05:13 PM

What did the 02 sensor say??

Steve Jones · #14 (**permalink**) 04-24-2002, 06:23 AM

Michael,
I'm at work and don't have any of my notes, so bare with me and take these numbers for what their worth. The O2 sensor output voltage varies depending on the type of throttle & load input, i.e. accelerating, cruise, decelerating, etc. and therefore, which carb circuits are active. As I recall, the voltage would rarely go below .8 V and only under thottle off deceleration. If memory serves me correctly (and it rarely does), a 14:1 air/fuel ratio should produce about 7.5 V. Anything above that is richer and below is leaner. I have settled on #71 primary jets and #80 secondary. I've tried all sizes down to #65's in the primaries (to the point where the car developed a "lean stumble" on transition from cruise to accel) and the O2 sensor still indicates rich most of the time.
I found the same thing as you with respect to the thermostat. I originally tried using a 160° and found that this engine needs to be at 180° to run good. Been using a 180° ever since.
My problem isn't that I'm fouling plugs under normal driving conditions. When I have a problem is when I have to start & run the cold engine for a short period of time such as loading it in the trailer or just firing it up during the winter to keep everything lubricated. If I don't run it for a good 15-30 minutes and get it totally up to operating temperature, the NEXT time I start it, one or two plugs will be fouled. I'd sure like to be able to load it on the trailer without worrying if any plugs will be fouled when I un-load it. If I'm loading it at 6AM the neighbors don't want to hear it running for 15-30 minutes!!

SCOBRAC · #15 (**permalink**) 04-24-2002, 09:07 PM

Steve,

Hmm.. you have all the bases covered.. I'm stumped.. All I get after shutting it down and re starting is a puff of fuel smoke..

You say they are fouled coming off the trailer.. Are they fouled to the point that they must be removed and cleaned prior to running again? Or are they just wet and sooty?? I know it sounds risky to leave them in and let the engine clean them warming up but I have never looked at my plugs after a brief start and stop (though it isn't something I regularly do) but I have never had them load up to that point... and as such have never pulled them out after such a brief run...

Sorry I couldn't be of more help.. I still don't think a non resistor plug would be the answer, even if you could find one..

Regards,

Steve Jones · #16 (**permalink**) 04-25-2002, 06:26 AM

Most of the time (if it's only one plug) I will go ahead and let it run up to operating temp and try to get it to clear, and it usually will. But I don't like washing down that one cylinder for 15-20 minutes until the plug starts firing!!
A couple of years ago, I made a set of those "car skates" that go under the tires just so I could move the car around the garage without having to fire it up (and foul a plug)!!!

I guess I'll just have to live with the problem for now, but thanks for your help Michael.

Steve

SCOBRAC · #17 (**permalink**) 04-29-2002, 02:12 PM

I can understand that.. Barring an ignition related problem I'm stumped.. I am not an expert on your ignition system, but I know MSD fires a full 20 degrees of crank rotation.. I hate changing things to change them, but have you considered trying an MSD?? The 6a can be had for like $150, The 6al with rev limiter is under $200..

If you buy it at a CSK (checker, schucks or kragen) you can get your money back if not 100% satisfied..

Good Luck,

mr0077 · #18 (**permalink**) 04-29-2002, 03:40 PM

Steve, just a WAG...I had a similar (but milder) problem with my car, found out it was the choke set too rich, while the fast idle screw was set to low. I kept increasing the amount of choke to get the idle right, just got worse. Since your prob is with cold starts, you might check the choke settings. LOL

Melzer · #19 (**permalink**) 05-20-2002, 05:54 AM

A couple of questions:

1) I just pulled my plugs to check for fouling. Current plugs are Autolite 45's. Is this the modern equvalent of the original BF32's?

2) Carb (Demon-650) seems to be running rich....plugs are carbon fouled - probably why it won't lite up.

Anybody have suggestions on how to lean out this Demon?

1963 427 center oiler/10.5:1/with iron heads/Edelbrock .572 cam/RPM Performer intake/Demon-650/MSD-6AL

Thanks in advance......Melzer



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