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Old 06-21-2005, 12:30 AM   #1
Berdoo John
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Question Correct spark plug gap on Ford 302 with HEI?

This is a freshly rebuilt 70's(?) 302 Ford. 700 miles on car (Model A). Everything on it was brand new, including HEI distibutor from Speedway motors and Comp Cam High Energy kit 218 (installed by engine builder). Plug wires that were installed initially were 7mm. I installed a fairly cheap set of 8mm wires on Friday after finding out the 7mm that were installed were inadequate for the HEI. Firing order has been checked several times and is correct. Champion plugs are gapped @ .044. This is third set of plugs I have tried. Motor smoothed out somewhat with the fresh plugs I put in Sunday but my symptons still exist.... Motor has a miss, can hear the valves ticking (they were snugged up in the beginning), and I have hesitation when I push on the pedal, even on the freeway, let off the gas to brake or coast, and push the gas pedal, hesitation.

According to my book .044 is the correct mid '70s Ford V8 gap with electronic ignition. In late 70s/early 80s gap opens to .050.

So as distributor efficiency/quality improves does the gap need to be larger?
From what I have read on online descriptions for HEI distributors they say they allow for gaps of .050-.055.

Should I open mine up some? Any suggestions? Thanks in advance. John
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Old 06-21-2005, 12:48 AM   #2
Mojo
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Default Re: Correct spark plug gap on Ford 302 with HEI?

maybe the tempature range is off a bit? Have you tried hotter or cooler plugs? I run a MSD box, my engine really woke up when I opened the plugs up to 60. I also trimmed the electrode back over the center of the plug. That helped a bit, but they tend to need to be cleaned more often. Not really fouling, they're just more sensitive to crap on them.
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Old 06-21-2005, 12:51 AM   #3
Berdoo John
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Default Re: Correct spark plug gap on Ford 302 with HEI?

No I haven't tried that. I just get whatever AutoZones 'puter says for mid/late 70's 302.
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Old 06-21-2005, 10:02 AM   #4
Berdoo John
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Default Re: Correct spark plug gap on Ford 302 with HEI?

Bttt.

In addition, can someone school me on how to determine if a motor needs a hotter or cooler plug?

TIA, John.
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Old 06-21-2005, 10:17 AM   #5
mikeyboy
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Default Re: Correct spark plug gap on Ford 302 with HEI?

step one...take the champion plugs and throw them as far as you can
step two...get a set of NGK V power plugs (78 granada 302)
step three... set gap @ .050
step four...get a GOOD set of wires.
step five.....drink Beer
bur seriously folks.....check the coil & see if it is internal resistance unit or if it is designed for use with a resistor, & check voltage at the coil.
how much timing do you have in the motor ?
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Old 06-21-2005, 11:08 AM   #6
AnimalAin
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Default Re: Correct spark plug gap on Ford 302 with HEI?

Your idiot pal here had some problems with running incompatible coils on electronic ignition (351W). Used the wrong one, run ok for a while, then run bad for a while, then won't run at all. Got the right one, and the damn thing goes like a train.
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Old 06-21-2005, 01:13 PM   #7
Derek
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Default Re: Correct spark plug gap on Ford 302 with HEI?

You've got an HEI in your ford? I am only asking because HEI is a GM term for their electronic ingnition systems (High Energy Ignition). I know that they are made for other applications though also. I am only askin becuse if you have an HEI ignition that would mean you have an in cap coil, is this correct? In my experiences an HEI ingnition works best somewhere between .050 and .060, so that's where I would start. Also, i would shit can the Champions too. Not a fan of their plugs, NGK are good, I prefer Autolites in V8 apllications though. That is just personal preference though, I run NGK's in all of my motorcycles and most of my 4bangers. As far as finding out about heat range, it's always been hit and miss for me. I know ther eis a formula somewhere, but I have never used it. If my ride seems to be runnin' lean when everything is tuned right, I go a step colder, and if it seems to run too rich, well do the opposite. Good luck and keep us posted.
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Old 06-21-2005, 01:52 PM   #8
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Default Re: Correct spark plug gap on Ford 302 with HEI?

ok.. this is just a theory as im having a similar problem when i went to the DUI ignition system with my ford... and again... i have not tried it yet, it is still sitting in the garage since paso.

to me, the hesitation could coming from the fact that with the new and improved spark, the engine is burning things much faster, and thus causing a lean condition... and that could be the hesitation. at least that is what mine is acting like. i have not investigated if it would be air/fuel ratio or accelerator pump shooters, cam, etc.

just an idea?
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Old 06-21-2005, 05:23 PM   #9
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Default Re: Correct spark plug gap on Ford 302 with HEI?

sorry... i mean maybe look at carb dial in rather than plugs ??
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Old 06-21-2005, 08:12 PM   #10
Berdoo John
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Default Re: Correct spark plug gap on Ford 302 with HEI?

Yes this Ford 302 motor has an HEI distributor in it. Looks like a few of you guys missed that part.

Here's proof: http://www.vintageperformance.com/re...stributors.htm

Mine is from Speedway Motors.

Thanks for the advice so far.
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Old 06-21-2005, 08:17 PM   #11
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Default Re: Correct spark plug gap on Ford 302 with HEI?

Im another one voting for trashing the Champs. Ive also had some Autolites bad right out of the box. Went with NGK in just about everything I own or build. I use platinums in my 351W truck; starts instantly in any weather and not a hint of problems.

Grab a spray bottle of water and check for vacuum leaks everywhere; check condition of wires (measure resistance) and be sure not sitting on exhaust. Cheap wires from AZ are pure shit. Go thru timing, be sure you dont have slop in timing chain or dizzy.
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Old 06-21-2005, 09:21 PM   #12
Mojo
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Default Re: Correct spark plug gap on Ford 302 with HEI?

platinum plugs are great, I ran them for a while, I hardly ever had to clean them and they always worked right. The MSD box was making them burn a little too hot, so I was getting spark ping during the summer, so I switched to normal plugs. Platinum plugs are worth the money...
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Old 06-21-2005, 10:12 PM   #13
RoadKat
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Default Re: Correct spark plug gap on Ford 302 with HEI?

U can read plugs by the burn color on the electrode. Fords seem to be happy with a dark tan color. And the hei will like a wide plug gap. Ford dis also do better wit a little recurve, but not too wild.
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Old 06-21-2005, 11:42 PM   #14
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Default Re: Correct spark plug gap on Ford 302 with HEI?

Quote:
Originally Posted by Toothpick
Bttt.

In addition, can someone school me on how to determine if a motor needs a hotter or cooler plug?

TIA, John.

Here's a start on how to read a spark plug correctly to tune for optimum performance.

http://www.dragstuff.com/techarticle...ark-plugs.html

http://www.dragstuff.com/techarticle...ead-plugs.html

http://yellowbullet.com/yellowbullet1_010.htm

-Bigchief.
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Old 06-21-2005, 11:57 PM   #15
Rustamino
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Default Re: Correct spark plug gap on Ford 302 with HEI?

Quote:
Originally Posted by Toothpick
Yes this Ford 302 motor has an HEI distributor in it. Looks like a few of you guys missed that part.

Here's proof: http://www.vintageperformance.com/re...stributors.htm

Mine is from Speedway Motors.

Thanks for the advice so far.
That's very cool, thanks for the link! I had no idea something like this was even being made. I have a freind who's been having a lot of trouble with his ignition setup in his '55 Crown Vic with a 302, this might be just the thing!
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Old 06-22-2005, 12:08 AM   #16
Derek
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Default Re: Correct spark plug gap on Ford 302 with HEI?

Quote:
Originally Posted by Toothpick
Yes this Ford 302 motor has an HEI distributor in it.
Yep, I woudl definitely open it up from the .044. Some of the earlier HEI's called for that stoc, but average was more like .050 or so and I've seen stock gaps with an HEI as high as .060 or so. The recurve might be a good idea also depending on what you got from petronix. If it's all gm type on the base plate also that's pretty easy too. nothing more than a spring kit.
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Old 08-28-2010, 03:59 PM   #17
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Default Re: Correct spark plug gap on Ford 302 with HEI?

Hello, i'm having a problem with my truck..
I have a 1994 f-150 2wd with a 302 EFI.
It has been running really bad lately.

I just checked the plugs they seem normal.
Except a few, that were deformed like got to hot on the prcelin.
The gaps went from where i gapped them at to over 60.
I have no idea how that happens.

But anyways the truck has been running weird, like it's getting to much fiel or not enough.
I have to kick in the passing gear to get it to go.
When at idle it runs ruff, and when taking off it runs like it wants to die.
At speed it bucks every so often.

I have tried to find out what it is, but i haven't had any sucess.
I don't have the money to take it somehwere to get it fixed.
Which i have a feeling it will cost an arm and a leg.

If any of you could help me out with this? i would be greatful.
Thanks
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Old 08-28-2010, 09:57 PM   #18
GMC BUBBA
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Default Re: Correct spark plug gap on Ford 302 with HEI?

Spark plug gap should go with engine design and combustion chamber design , NOT the ignition system.

I would suggest using the gap that orginally was spec-ed for the engine.

Changing the ignition system doesnt change the engines spark requirements.
HEI was developed for lean air fuel and epa 50,000 mile emissions requirements. Low compression and lean air made the mixture very hard to fire and keep ignited.
One of the better ignition modules on the amrket with variable dwell control and current limiting circuits.
We use this controller in many other igntions .

Just something to think about.
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Old 08-28-2010, 10:25 PM   #19
Francisco Plumbero
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Default Re: Correct spark plug gap on Ford 302 with HEI?

Well shit Bubba, you sure killed this thread. How do you feel about the NGK platinums, I use the Champions myself, I clean the once a month.
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Old 08-28-2010, 10:44 PM   #20
Fiddytree
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Default Re: Correct spark plug gap on Ford 302 with HEI?

NGK, .050, 650 Holley, alum heads, HEI from Performance Dist. NO platinum in carb motors.

YMMV. (Your mileage may vary.)
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