Replacement TI Coil ??

[Edward B.]

Gents, I'm getting my TI distributor rebuilt and ordering a new wiring harness, connectors, etc..., but I have a question about the coil. The original 263 coil is MIA so I'll have to get another one. I have the replacement solid state amplifier module installed in my amp and looking at the Paragon web site, it states in Tech Tip #48 that I can "use ANY stock Delco coil rather than purchasing an expensive TI coil". I really don't want to spend $150 on a repop 263 coil if ANY stock Delco coil will do (especially since everything's hidden under the ignition shielding anyway and you can't see it), but I don't see how a stock Delco 20k volt, 1.4 ohm coil will work when the TI coil specs out as 40k volts and .45 ohms! Am I missing something or is Paragon wrong? Paragon sells a replacement TI coil (P/N 14470) for $65 but does anyone have any input on this coil? It's half the price of the repop 263 so that's good for my pocket book! I was also looking at the Flame Thrower II coil. It's very close to what the original 263 coil was - 45k volts and .6 ohms.

If anyone has info on a good replacement TI coil, please let me know.

Thanks
Ed

[Duke W.]

Re: Replacement TI Coil ??

but I don't see how a stock Delco 20k volt, 1.4 ohm coil will work when the TI coil specs out as 40k volts and .45 ohms!

Single point and TI coils only generate about 25kV open circuit voltage (about 30 kV for the HEI). A "40kV" coil would break down the insulation if a plug wire was disconnected.

Open circuit coil voltage is a MEANINGLESS number, but vendors hype it to the ill-informed.

What really counts is per spark energy, which is measured in millijoules. The TI and HEI offer twice the per spark energy as the single point system because the primary side had less resistance, which means greater primary current, and greater primary current means greater per spark energy.

Maximum open circuit voltage is a function of coil winding ratio. The spark will initiate somewhere in the 5-10kV range depending on operating and plug conditions and then drops to several hundred for the remainder of spark duration, so 25kV open circuit voltage is more than adequate.

The long spark duration of inductive systems work much better to light the fire of lean, low density mixtures compared to the short spark duration of CD systems. That's why all road cars have inductive systems to this day. The only production CD system I recall was from GM in the late sixties, and it was short lived.

The single point yields a spark duration of about 120 microseconds, and the TI and HEI are about 180.

A single point coil will probably work okay, but won't generate quite as much energy. Any replacement coil that has the same primary resistance as the TI coil will probably be okay too, but if such coils can actually generate 40kV open circuit voltage (which I actually doubt) an open circuit condition could damage the OE type plug wire insulation since they were not designed to handle such high voltage.

Greater primary current means more heat is generated in the coil, so heat transfer needs to be considered in coil design.

Back in the fifties/sixties when Corvettes used a 0.3 ohm ballast, the increased primary current didn't seem to shorten coil life, but burned points were fairly common.

Duke

[Edward B.]

Re: Replacement TI Coil ??

That's really good info Duke. Thanks.

So basically, both the points and TI coils were similar EXCEPT for the primary resistance (1.4 ohm for the points coil and .45 ohm for the TI coil). What I need to find out then is the ACTUAL spark voltage (not the open circuit voltage) of the various low ohm coils for sale. I've sent an email off to Pertronix to see what they say. I can get the Pertronix Flame Thrower II for $38 bucks from SUMMIT RACING.

Ed

[Duke W.]

Re: Replacement TI Coil ??

Forget about voltage!

When the main power transistor (or points) open, voltage starts building at the spark plug center electrode. A few microseconds later when voltage achieves somewhere in the 5-10kV range a spark will jump the gap and voltage drops way down. Any automotive 12V coil will provide the required voltage.

Try to find a coil that's somewhere between 0.5 and 1.2 ohms primary resistance and hope that it's designed well enough to handle the heat from the high primary current without frying.

Consider a generic ten-buck replacement coil and see if it lives.

You won't get any relevent or meaningful technical information from vendors. They don't have the foggiest idea how ignition systems actuallly work at any level of technical detail. They might have a spec for primary resistance, but don't count on it.

The info in my prior post is from SAE papers on the TI and CD ignition systems that were written back in the sixties.

Duke

[Edward B.]

Re: Replacement TI Coil ??

Well Duke, I'm leaning toward THIS ONE (the Pertronix Flame Thrower II - P/N 45011 - for $37 bones). It's the closest thing I can find. It's .6 Ohms, a 108:1 winding ratio and I suspect, 20k to 25k REAL WORLD output voltage. I looked at the various parts houses like AutoZone and O'Reilly, and all they carry is the 1.7 Ohm points coil, so that's no good.

Dave Fiedler doesn't recommend the GM replacement (P/N 12337166), so it's either the reproduction 263 coil for big $$$, the replacement TI coil for medium $$$ or an aftermarket replacement like this one for reasonable $$$. I have a feeling the replacement TI coil the vendors sell is either the 12337166 or an aftermarket coil like the Flame Thrower!

By the way, if I do end up trying the Flame Thrower coil, it won't fry my amp will it?

Ed

[Duke W.]

Re: Replacement TI Coil ??

As long as the replacement coil has no more resistance than the OE coil then current won't be any greater than with the OE coil and the amp should not be overloaded. There's also a resistance wire in the circuit - the one with the off-white braided insulation, but I don't recall its value. Nominal current in the TI system is about 8 amps vs. 4 amps on the single point system... double the current, double the energy.

The HEI is basically the same circuit as the TI, but implemented in a thick film hybrid circuit rather than discrete components on a circuit board, and the HEI adds a variable dwell feature.

What coil does Fiedler recommend for the TI system?

Duke

[Edward B.]

Re: Replacement TI Coil ??

Thanks again Duke. Dave only sells the "replacement" coil and doesn't say what he recommends (at least he doesn't on his site). I tried emailing him some questions a week or so ago but never got a reply.

I'd like to hear from anyone that's purchased the repop and/or the replacement coils. Performance, life span, overall satisfaction or dissapointment?

Ed

[John H.]

Re: Replacement TI Coil ??

Well Duke, I'm leaning toward THIS ONE (the Pertronix Flame Thrower II - P/N 45011 - for $37 bones). It's the closest thing I can find. It's .6 Ohms, a 108:1 winding ratio and I suspect, 20k to 25k REAL WORLD output voltage. I looked at the various parts houses like AutoZone and O'Reilly, and all they carry is the 1.7 Ohm points coil, so that's no good.

Dave Fiedler doesn't recommend the GM replacement (P/N 12337166), so it's either the reproduction 263 coil for big $$$, the replacement TI coil for medium $$$ or an aftermarket replacement like this one for reasonable $$$. I have a feeling the replacement TI coil the vendors sell is either the 12337166 or an aftermarket coil like the Flame Thrower!

By the way, if I do end up trying the Flame Thrower coil, it won't fry my amp will it?

Ed

Ed -

If you get the Pertronix Flame Thrower coil, keep an eye on it - that particular coil used to be dead-reliable years ago, but since they sent the manufacturing of that coil to China two years ago, the forums are full of failure stories and grief over replacements.

[Mike W.]

Re: Replacement TI Coil ??

I bought the replacement coil from Dave. Had it in the car for about 4 months - so far so good. 1971 LT1

[Edward B.]

Re: Replacement TI Coil ??

If you get the Pertronix Flame Thrower coil, keep an eye on it - that particular coil used to be dead-reliable years ago, but since they sent the manufacturing of that coil to China two years ago, the forums are full of failure stories and grief over replacements.

That's one of the unknowns about trying to find a good, REASONABLY PRICED TI coil. The Pertronix coil is made in China, but so are some of the reproduction coils. Heck, MOST of the "GM Authorized" parts are made in China!

Paragon has two 263 coils. One made in China and one made in the US. They also have the replacement coil that's made in the US so I may have to bite the bullet and get that one. I don't need the high priced "263" logo coil. It's under the ignition shielding and my car is FAR from "correct" anyway. I just want something that will work as designed! I was hoping someone would know what the replacement coil actually is. Pertronix? MSD? Accel? Standard Motor products? WHO exactly makes the replacement coil?

I bought the replacement coil from Dave. Had it in the car for about 4 months - so far so good. 1971 LT1

Thanks Mike. I'm assuming there's nothing on the coil or the box it came in to indicate WHO actually made it?

Ed

[Mike W.]

Re: Replacement TI Coil ??

Ed,

I don't recall. I'm sure Dave could tell you. He rebuilt my distributor and amp. Everything works really well. The coil has the correct labeling, but no number. The coil is exposed during judging with the distributor shielding removed. The coil scored well two weeks ago at the Houston Chapter Meet.

Mike

[Edward B.]

Re: Replacement TI Coil ??

I was afraid of that. More than likely there wasn't any identifier on the box or the coil.

My car is my daily driver (although I work out of my house and rarely go anywhere). Since I don't judge it, "numbers" aren't important to me so I'll probably go with the "replacement" coil from Paragon since it's half the price of the 263 and made in the USA.

However, if anyone ever finds out WHO makes the replacement, you might want to post the info anyway. Someone in the future may do a search on this and the info would be nice to have.

Thanks again all.

Ed

[Edward B.]

Re: Replacement TI Coil ??

Update - As I stated above, I contacted Pertronix asking them if their Flame Thrower line of coils would work with the TI system and they replied that the Flame Thrower II would work but not the Flame Thrower III. I also asked where their coils were manufactured and they no longer source them from China, but Mexico. Not sure if this is an improvement or not!

Ed