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tr upgrade for 93 YJ ??

1K views 15 replies 8 participants last post by  RRich 
#1 ·
a buddy has a 93 YJ (6-cyl) and was complaining that it is sluggish. so i was thinking of the TR upgrade, but i can't remember if you can do that on a 93. if yes, can you post a link. if no, any other ideas? sorry, i don't know anything about YJ's.

thanks all
shawn
 
#10 ·
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so why does a larger dist cap and hotter coil help on a cj but not on a yj?

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EERRR it does???? Worked on my YJ like a champ,,, hehe but I'm carbed /ubbthreads/images/graemlins/wall.gif
 
#11 ·
[ QUOTE ]
so why does a larger dist cap and hotter coil help on a cj but not on a yj?

thanks
shawn

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The "Ford TFI upgrade" was/is more of a fad than a real benefit. Hey, everybody is doing it! it must be great! I'll probably catch heck for this but lets just call it an opinion based on personal expierience.
It doesn't help as much as some people think it does on a CJ. If your CJ was running like crap because it needed new ignition parts then it will help a lot but new stock parts would help just as much. The rest is a sort of placebo effect combined with "Well, I did this mod, now I've got to justify it." Nobody wants to say they did a mod and it was a total waste of money.

I did the TFI Ford "upgrade" on my CJ and I can tell you Yeah, it was worth it, because otherwise I'd have to admit I can't really tell any difference and when I put the old parts back on It runs exactly the same. The only thing I like about it is the larger dia. SP wires. I would think they are less prone to damage and leakage. My CJ runs great with the upgrade! (PSSSST.. (whispering)it runs just as good with out it!)

On a 93 YJ the ignition is already upgraded more than it needs to be And the regular size dist. cap is proof a larger one isn't needed when you go TFI on a CJ. At least not on mine, and I've swapped them more than once. /ubbthreads/images/graemlins/40BEER.gif
 
#12 ·
The large cap and coil by themselves aren't the whole upgrade. The motorcraft module needs to be replaced with either an HEI module or an MSD. Then the plug gaps can be opened a bit. That is where the benefit comes from.
 
#14 ·
Quite true - sort of.
The larger cap does nothing - except it has better insulation - so you can use a hotter ignition system.

The TFI coil does nothing -- unless the ignition resistor is eliminated -- but then the regular module's getting too much current through it - won't last long like that. But it will give a longer and hotter spark.

Best way - use the big cap - and use a module equipped to drive a better coil without the resistor. That means an GM HEI module, no ignition resistor, and either an HEI coil or TFI coil. Or - a complete MSD system.

The result is more available voltage (another 10 KV), faster rise time (about 5 times faster), and a longer spark duration (2.5 ms vs .75 ms.)
It will fire a wider gap on the plug - more spark to start more fire!

The effect - easier starting, more complete combustion -- means more power, and better mileage.

CJ or YJ, MB, Chevy, Ford, Subaru, Model A, Duece Coupe, etc.
 
#15 ·
i thought that part of the problem with the small (ish) distributor was that you got cross fire at high rpm's and that the larger distributor eliminated that? am i wrong?

thanks
shawn
 
#16 ·
If it over advances it can crossfire. But that's a problem that needs to be cured anyway. Too much advance is detrimental to the engine. If it was true, then they wouldn't have been used by everyone for so many years.

The larger cap spaces the terminals farther apart. The larger distance affords better insulation between them.
But -- some GM HEI's stock use the smaller configuration with the hotter spark - like 454's.

The only time it should be a problem with a hot spark is if you had a broken plug wire - open circuit - then the voltage can climb high enough to jump across the terminals. Normally it's far easier for the spark to jump the plug gap. After all, the voltage can only go as high as the smallest gap will allow - and that should be the plug gap.

I've successfully done the HEI conversion on the smaller capped distributors. The only thing to look for is the barrier ribs inside the cap between the terminals. The cheapies and off brands (usually Chinese junk) don't have any, or near as many ribs as the good caps do.

As always, stick with quality and avoid trouble.
 
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