TFI vs. HEI

[RRich]

It sure suppresses the sex drive!

[jeepsr4ever]

You can mix and match to make a hybrid system and get the best of all worlds. I like the HEI unit alone because it gets rid of your coil, ignition control module and a boatload of bulky wires. Are there better ways to go ...sure but HEI units work pretty damn well. If you run off and buy one there are chinese imports raining all over the USA. Make sure and use a OEM AMC V8 gear on it OR a MSD 8005 gear or you will eat your cam gear.

[TeamRush]

WOW!
Did I take a ton of crap right here on this forum back in about '98 or '99 when I suggested anyone switching to a 'Jacobs' ignition should try 'Tune Up' parts instead of forking over for a full on ignition system made from 'Proprietary' parts you had to special order.

The crap REALLY hit the fan around here, and I got called every name in the book, called a liar, an idiot, and generally generated a visceral response from the guys that spent all that money on the Jacobs with a 3 to 6 month warranty...

Went through pretty much the same thing when the 'HEI Clones' hit the 'Internet' for cheap...

So, after slugging it out with the keyboard commandos for 13-15 years about this, I'm still here...
3 million searches for the particular 'Style' of ignition I recommend a year,
And more pirated, cloned, and just plain PLAGIARIZED pages dedicated to the subject,
Most having a lot of inaccurate or just plain wrong information....

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THIS IS THE STRAIGHT SCOOP...

There are a lot of variables here,
One is the type of engine you have currently,
The year of the vehicle,
You skill level with running some simple wiring, ect.

If you have a '78-Newer vehicle, you already have a Jeep/Motorcraft distributor.
That distributor is Upgradeable, strong signal trigger, good solid advance mechanisms, and is more tune-able from the factory than the Factory versions of the GM HEI distributor.

It also doesn't have the 'Fatal Flaws' the GM HEI and it's clones have...

If you have the '78 to '90 AMC engine, you have the 'Jeep' version of the Motorcraft distributor, and that is a VERY good place to start!

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*IF* you have an I-6 engine, and it's '77 or older,
Then your most cost effective way to do things is an HEI conversion.
Use a Chevy 250 CID, I-6 distributor.

My personal favorite is the '76 Chevy Blazer distributor, since it comes with a remote ignition coil.
Gets that coil out of the distributor cap so you can use a larger, more effective coil than the 'In Cap' HEI coil,
And you don't have the voltage leaks you have with the 'In Cap' HEI coil.

There are other years that have In Cap coils, if that is what you are looking for.

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*IF* you have a '77 or older AMC V-8 engine,
Then I would stay away from any of the HEI Clone distributors,
(With the excpetion of MSD or DUI, which are the ONLY two I know of first hand that are close to being 'Correct' for fitting your engine)...

GM HEI distributors were never issued from the factory,
There are several 'Clone' versions out there, and 99% I've seen are WRONG,

Wrong gears, wrong install height, wrong rotor phasing, wrong advance curves, cheap import parts, and generally very poorly built all the way around.

For one that is 'Correct', you are going to shell out $300 to $500.
REALLY EXPENSIVE.

A 'Better' choice is a $50 Jeep/Motorcraft distributor,
$35 worth of premium cap & rotor,
And a $20 to $200 module of your choice.
Wiring is minimal, you get choice of several types/sizes of ignition coils,
And they come from the parts store ready to run, already tuned NOT to destroy your engine...

--------------------------------

First, since he hasn't registered as a Vendor or labeled his post as a vendor,
You should know that...
"Jeepsr4ever" is 'Bulltear' and they SELL HEI distributors.
Keep that in mind.

Originally Posted by jeepsr4ever

You can mix and match to make a hybrid system and get the best of all worlds.

This statement is true,
You can wring more spark energy out of a combination of corporate manufacturer parts cheaper than you can any other way.
The addition of a couple of after market parts will increase spark energy 600% to 1,000% above that...

I like the HEI unit alone because it gets rid of your coil, ignition control module and a boatload of bulky wires.

The above statement is false.
You still have an ignition coil, with his brand of HEI clone product,
It's in the distributor cap, which is a very poor design (even GM finally changed it!),
You still have a 'Control Module', it's inside the distributor it's self with all those high voltage discharges grounding out around it,
And it still has to struggle for an electrical 'Ground' as the distributor housing corrodes over time, gets coated with oil residue from the engine, ect.

Are there better ways to go ...sure but HEI units work pretty damn well.

Ambigous...
If you have a Jeep/Motorcraft distributor,
For the cost of cap, rotor, plug wires and a $20 module, you can out perform the HEI units.

If you have breaker points or Prestolite Ignition ('74-'77)
The HEI is an 'Upgrade' to both of those, it's more reliable, but still has 'Issues' of it's own.

To be fair, you could take it either way, depending on what year of engine you are talking about.

If you run off and buy one there are chinese imports raining all over the USA. Make sure and use a OEM AMC V8 gear on it OR a MSD 8005 gear or you will eat your cam gear.

He's correct about the 'China' and 'Import From Elsewhere' parts, they are TOTAL CRAP in about every case.

On the other hand, the MSD 8005 Gear is expensive,
(same cost as a Jeep/Motorcraft entire distributor from the parts store expensive!)
But the MSD gear is DEAD SAFE, I've not heard of an MSD gear eating up a stock engine camshaft gear yet...

The bad news is, they don't always fit the 'HEI Clones',
The clone shaft sizes are all over the place, from 0.430" to over 0.500"
The MSD gear is 0.500" shaft size,
GM Factory HEI shafts are *Usually* 0.488" to 0.490", so the MSD gears don't usually fit the factory GM HEI shafts too well, a little sloppy,

And the V-8 gears go on the shafts at the wrong install height when used on an I-6 distributor...
That makes them contact the I-6 camshafts in the wrong place, and you get premature wear or complete failure out of the deal...

I'm sure this is going to create issues with the 'HEI FAN BOYS', and they are going to jump all over me again like usual instead of making rational arguments,
So I'm going to PM you some links...
You have a look, decide for your self...

[TeamRush]

Will,
Something I see right away I won't do, and there are some VERY good reasons why I don't...



You have the trigger pair of wires twisted around each other, which is VERY good to do,
But they are UN-SHIELDED, and they are bundled with high current switching wires to the coil.

This can cause a lot of false trigger 'Electrical Induction' problems.

Electrical induction is fairly complicated, so if you want it explained, I will.

I would separate those trigger wires from the bundle, and keep them close to metal, which works to block the induction process.
Using metal shielded wire that is electrically 'Grounded' will help block the induction process also.

Wiring for anything that is 'Switching' on and off rapidly will cause induction false triggers,
Blower motors, ignition coils, spark plug wires, ect.

If you seem to run out of power as RPM increases, before you should run out of power, then you probably have induction/false trigger problems...

[Caver Dave]

Originally Posted by TeamRush

But they are UN-SHIELDED, and they are bundled with high current switching wires to the coil.

This can cause a lot of false trigger 'Electrical Induction' problems.
Wiring for anything that is 'Switching' on and off rapidly will cause induction false triggers,
Blower motors, ignition coils, spark plug wires, ect.

The EST in close proximity to the GM TFI coil had me stumped until it was suggested I move the EST (worked perfect ). I ended up moving the EST slightly away from coil (1" more) and shielding (AL "tape" spirally wrapped around the trigger wires and grounded at the dizzy) them... has worked fine since...

Originally Posted by TeamRush

Thanks for the pic! I'm finally (after having all the bracketry/York for the past 9 years) adding the OBA and was having a hard time figuring out how everything went together!

[WILL]

Originally Posted by TeamRush

If you seem to run out of power as RPM increases, before you should run out of power, then you probably have induction/false trigger problems...

That may explain why the fuel system needs constant adjustment and seems to run rich and lean at random. I'll have to try seperating and shielding them. I twisted them together when I installed them and kept them close to the block but didn't think about that span from the module to the block.

[TeamRush]

Originally Posted by WILL

That may explain why the fuel system needs constant adjustment and seems to run rich and lean at random. I'll have to try seperating and shielding them. I twisted them together when I installed them and kept them close to the block but didn't think about that span from the module to the block.

Induction is a big deal when you have those low voltage trigger wires run for a long span directly in contact with the high current switching coil wires.
Even worse if you get them next to spark plug wires.

I use to run mine through a metal tube when we ran the super high current racing ignitions. Couldn't even keep them safe with the "Average" shielded wire sets.

Anyway, hope this helps.

[Jim_Lou]

I strongly suspect that no one else is reading all this clanging of Richard Edwards together. If any conclusion is ever agreed upon, please post it in another thread. Attachment 77689

[tinycj7]

Originally Posted by WILL

This piece of bent metal with the heat sink compound that came with the module is all the heat sink I have.

Now THIS is a working mans Jeep.

No disrespect, just an observation to this picture.

You might clean off the top of the battery. That acid and dirt create an electric charge. Long story short, it pulls down your battery voltage all the time. This will prematurely wear out your entire charging system.

That black possible ground wire that attaches by the air conditioning compressor, might want to relocate that. If anything it will keep it out of the fan belts/blades.

I would solder the connectors/wires at the ignition module. Place a bit under the blue insulator area. This creates a 100% bond from connector to conductor. Copper is soft as we know and will loosen it's poor crimp connection over time. This will cause this device to stop functioning. Not to mention the corrosion possiblity here. We all need our ignition system to work properly. Just noticed the battery post. Some solder at those connections couldn't hurt. And some grease or Vaseline around each post is a good idea. Keeps the acid off the posts. Which leads to corrosion and so on......

I would firewall mount your coil and ignition module. Keeps them off the hot engine. Cooler coil will last longer and have less resistance = more spark longer. Heat increases resistance in copper wires. Gently zip tie the wire harness and put some black air duct or wire loom around it all to conceal. Would clean up your install considerably.

REMOVE those cheap black plastic ignition wire holders. All they do is promote cylinder to cylinder misfiring, which we DON'T want. We need an inch or two minimum around our spark plug wires. If you doubt this just grab your ignition wires with the engine running. You'll quickly see they leak a little, lol.


tinycj7

[WILL]

Originally Posted by tinycj7

Now THIS is a working mans Jeep.

No disrespect, just an observation to this picture.

You might clean off the top of the battery. That acid and dirt create an electric charge. Long story short, it pulls down your battery voltage all the time. This will prematurely wear out your entire charging system.

That black possible ground wire that attaches by the air conditioning compressor, might want to relocate that. If anything it will keep it out of the fan belts/blades.

I would solder the connectors/wires at the ignition module. Place a bit under the blue insulator area. This creates a 100% bond from connector to conductor. Copper is soft as we know and will loosen it's poor crimp connection over time. This will cause this device to stop functioning. Not to mention the corrosion possiblity here. We all need our ignition system to work properly. Just noticed the battery post. Some solder at those connections couldn't hurt. And some grease or Vaseline around each post is a good idea. Keeps the acid off the posts. Which leads to corrosion and so on......

I would firewall mount your coil and ignition module. Keeps them off the hot engine. Cooler coil will last longer and have less resistance = more spark longer. Heat increases resistance in copper wires. Gently zip tie the wire harness and put some black air duct or wire loom around it all to conceal. Would clean up your install considerably.

REMOVE those cheap black plastic ignition wire holders. All they do is promote cylinder to cylinder misfiring, which we DON'T want. We need an inch or two minimum around our spark plug wires. If you doubt this just grab your ignition wires with the engine running. You'll quickly see they leak a little, lol.


tinycj7

That picture was taken Sept 2004. The battery (and engine and transmission for that matter) has been changed since then. This battery is just dirty like the rest of the engine compartment. Here's an updated picture. Had a module go bad and that has been changed too.

Ignition connections haven't been a problem.

I can grab the spark plug wires with it running with no noticible voltage leaking. Without the spacers, they would be laying in contact with each other which I think would be worse.

The black wire from the grill shell to the compressor is several inches away from any moving parts and can't reach any even when pushing on the wire. It connects my grill (and thus headlights) back to the engine ground. I have another from the alternator case to the negative battery terminal.