spark plugs, match to motor or igniton?

Landpimp

 
 
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Say on my 77 2F with fj60 ignition/dizzy, do I want to use plugs for a 77 2F or a fj60?

never had thought of this till today

John
 
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i would go with the plugs for the motor.
i would think that the ignition could probably handle whatever plug that was in there.

i order 78 2f plugs for my 69/40 cause thats the motor thats in it.
with modified ignition.
 
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I know my 135 F takes different plugs than my 155 F, and it is the distance from the base of the screw to the end of the electrode that makes the difference. It has to be the correct relative place in the cylinder to make the spark work right. I would say definitely go by the engine.
 

cruiserbrett

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I would go with plugs for the ignition. compression ratio and other factors are similar for both motors, ignition is certainly stronger with the FJ60 dist/coil. Maybe the FJ60 plugs take advantage of the ignition better???

I think my 76 2F took BPR5ES NGK plugs. what's the FJ60 take?
 
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you could still open the plug gap

cruiserbrett said:
I would go with plugs for the ignition. compression ratio and other factors are similar for both motors, ignition is certainly stronger with the FJ60 dist/coil. Maybe the FJ60 plugs take advantage of the ignition better???

I think my 76 2F took BPR5ES NGK plugs. what's the FJ60 take?
just slightly to get a bigger spark.
 

Pin_Head

 
 
 
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I would be surprised if it makes any difference even if the plugs are different in the first place.
 

honk

 
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The plugs are designated for reach and heat range. Reach is the depth of thread usually and heat range is variable somewhat to correct for driving conditions - cooler for high rpm and high ambient temps, hotter for idle and low rpm operation in cooler climes. (cooler plugs have a shorter insulator but that isn't what the reach spec is about).

Plug gap is a function of available arc energy - voltage.

So I'd buy plug for a particular engine due to reach and gap them for a particular ignition system due to voltage.

Aside:
High available voltage is the reason HEI (High Energy Ignition) systems can use such a large gap.
Large gap produces a hot long duration arc fully igniting the fuel charge and producing a potential for better performance in both total output and fuel economy.
 

honk

 
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brian said:
so then how big a gap should a 2f with an HEI setup have?
more than .035?
Yep. They started at .060" when GM first brought out the system. I'm not sure what a new car spec is or whether it's been changed over the years but if you've got one I'd say that trying out .050" won't hurt and might amaze you.
 

brian

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i would say it's larger, almost twice as large.

i'llll, have to let my Friend know this, so He can properly gap HIS plugs........
 

honk

 
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brian said:
i would say it's larger, almost twice as large.

i'llll, have to let my Friend know this, so He can properly gap HIS plugs........
Could be - as I said, I don't know how far they've brought it. But the gap ought to be in line with the spec for the system. It goes to how much voltage is used. I mean if it's a '75 HEI and that year used .060" then so should the current user. If as you say newer systems are using .10" and your system is one of those newer ones then .10" would be your gap.

Boy that's a big gap! Hard to imagine, but that's about the same thing I said when I first heard about HEI maybe 30 years ago. :)
 

Pin_Head

 
 
 
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honk said:
Large gap produces a hot long duration arc fully igniting the fuel charge and producing a potential for better performance in both total output and fuel economy.
Performance and economy gains for high voltage ignitions are one of those things that sounds good, but in practice it doesn't really accomplish anything.

The reality check is in the tail pipe. For your average low performance 70s engine in good condition, the unburned hydrocarbon emissions in the exhaust is in the range of parts per million. This means that 99.9999% of the fuel is ignited and burns with a low voltage ignition, which doesn't leave you with much room for improvement in combustion efficiency.
 
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John,

I'd go with plugs for the motor. I don't really think that any advance curve built into the distributor is going to have any effect on the plug difference. What have you been using and how has it been sounding/running?
 

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Quote:

>>Aside:

Large gap produces a hot long duration arc fully igniting the fuel charge and producing a potential for better performance in both total output and fuel economy.

<<

I think Honk used to write marketing brocuures for GM.

That said - I agree with him (and everyone else). Pick the plugs for the motor and gap for the ignition.

Rocky
 

honk

 
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Rocky_LC said:
Quote:

I think Honk used to write marketing brocuures for GM.

That said - I agree with him (and everyone else). Pick the plugs for the motor and gap for the ignition.

Rocky
LOL! No, but if I had I'd probably have been paid better than I was at the time. I think that GM came out with the system as part of their attempts to meet the then new and for the manufacturers very difficult to meet federal emmissions standards. As such it's one of the better ideas - far better than the screwed up carburation, the injection of raw air behind exhaust ports, and the myriad heaters, coolers, fans, and other attempts to clean up tailpipes without having the expense of major retooling and innovative engineering.

A hot and long lasting spark will provide a complete burn despite a host of conditions whether they are poor engine tune or condition, varied load presentations, changes in elevation, accelleration, decelleration, or lack of maintenance. It's an enduring system and it's been adopted in one form or another by most other manufacturers through the years.

All that said, do the Toyota sixes we deal in here need it? No, not if everything is working well and certain preferred parts are installed other than HEI. I don't have it on either of my running FJ40s - yet. But I've seen it bring an intractable engine into line, improving smoothness and overall driveability. I've got an HEI distributor on a shelf that I put a Toyota gear on but haven't tried it yet. One day I will though, just for kicks, and if it does good I've got to problem using what works. I would never pay the price for that conversion kit though - too much money. I picked up the distributor for $20. and converted it myself.

Sidetrack a thread??.......Who? Me? :grinpimp:
 

Landpimp

 
 
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thanks guys, I guess I worded my question wrong.......what I was meaning to say was gap ;)

but yeah I will regap the plugs to the fj60 dizzy, I don' think there is actaully much differene in gap.

John
 

brian

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opened mine up from .035ish to .060ish.
starts noticably better(before it would putter to life, now it roars up), even though that was never a problem before.
it had a slight bottom end hesitation(pulling away from a stoplights and such), that is gone, and it "seems" to be a little more peppy.
if it set idling it would load up and foul a cyl(not sure which)out, hav'nt "checked" that yet to see if it will do agian.

here soon i should play with my jetting(weber38/38).
 
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