no spark!?
red75cj5
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- i have a 75 cj5 with a stock amc 304, t case front and rear diffs as well
no spark!?
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TeamRush
Active Jeeper
There are some questions you need to answer.
Since the '75 year AMC 304 used a Prestolite distributor/ignition,
And they were VERY unreliable,
Many Previous Owners (POs) have changed them out for something different.
A good 50% of the ones that go through my garage were converted from Prestolite,
SO!
With that in mind, you might want to check and see, get back with me and I'll guide you through your testing and getting it running.
------------------------
A AMC 304 is a good start, but I need to know if you have a PLASTIC VACUUM ADVANCE on your distributor.
If it's METAL, but there is only ONE wire going to the base of the distributor,
It's a DELCO REMY distributor. (Breaker points version)
If it's METAL, and there are THREE wires going into the base of the distributor,
It's probably a Jeep/Motorcraft transplant.
PLASTIC vacuum advance was only used on one Jeep ignition systems, and that was Prestolite.
Once I know which ignition we are dealing with, I'll be able to guide you through checking things out.
------
One thing I would do,
Pick up a test light.
Looks like ice pick with a bulb in the handle and a wire coming out of the handle someplace with an alligator clip on the end of the wire.
This thing will tell you which side of the fire wall your issue lies,
And help you trace EXACTLY what is going on.
Parts stores have them from $6 to $25, and being more expensive doesn't mean it's more useful,
A cheap one will do, Just don't get the LED version, you want an actual BULB.
Since the '75 year AMC 304 used a Prestolite distributor/ignition,
And they were VERY unreliable,
Many Previous Owners (POs) have changed them out for something different.
A good 50% of the ones that go through my garage were converted from Prestolite,
SO!
With that in mind, you might want to check and see, get back with me and I'll guide you through your testing and getting it running.
------------------------
A AMC 304 is a good start, but I need to know if you have a PLASTIC VACUUM ADVANCE on your distributor.
If it's METAL, but there is only ONE wire going to the base of the distributor,
It's a DELCO REMY distributor. (Breaker points version)
If it's METAL, and there are THREE wires going into the base of the distributor,
It's probably a Jeep/Motorcraft transplant.
PLASTIC vacuum advance was only used on one Jeep ignition systems, and that was Prestolite.
Once I know which ignition we are dealing with, I'll be able to guide you through checking things out.
------
One thing I would do,
Pick up a test light.
Looks like ice pick with a bulb in the handle and a wire coming out of the handle someplace with an alligator clip on the end of the wire.
This thing will tell you which side of the fire wall your issue lies,
And help you trace EXACTLY what is going on.
Parts stores have them from $6 to $25, and being more expensive doesn't mean it's more useful,
A cheap one will do, Just don't get the LED version, you want an actual BULB.
richardoutwest
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Red7, you just got the attention of one of the most knowledgeable persons to jeep ignitions on the planet! If your have the prestolite ignition, do yourself a huge favor and do an upgrade, a few to choose from, not very expensive at all and never have trouble again! TeamRush is the man to walk you thru it and answer all your questions.
There are several others on here that are extremely knowledgeable and will be glad to help you out.
There are several others on here that are extremely knowledgeable and will be glad to help you out.
red75cj5
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- i have a 75 cj5 with a stock amc 304, t case front and rear diffs as well
I have a test light!!! the vacuum advance looks like it is plastic but it sounds like metal with only one wire going to it! it doesn't look like the metal ones that looks kind of like a top. it looks more like a set of eyes. if that helps at all
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red75cj5
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- i have a 75 cj5 with a stock amc 304, t case front and rear diffs as well
richardoutwest, that is good to know that he is very knowledgeable in ignitions. if it is the prestolight i will defiantly change it out. just need to know what all i need to get to change it out. thanks
TeamRush
Active Jeeper
If you can't tell metal or plastic, use a magnet.
When you say looks like a 'Top' that leads me to believe someone has swapped out your Prestolite and swapped in a Delco Remy Breaker Point distributor.
If there is one wire that goes directly to the ignition coil negative terminal,
Then it's a breaker point distributor, probably a Delco Remy version, which isn't too bad to upgrade to electronic ignition...
What usually happens with the breaker point ignitions is, the top bushing wears out and you wind up with a Dwell angle that won't support the spark cycle.
--------------------
You have two or three choices, depends on your wallet and skill level...
One is an aftermarket HEI distributor, which I DO NOT recommend for a V-8 engine.
A HEI that is trustworty will run you $300+ (and about $100 more for good plug wires, cheap wires and HEI's don't get along at all).
HEI distributors also get in the way of the power steering pump, which is a HUGE pain in the azz when you go to install.
----
The second choice, and the one I recommend,
Is a factory Jeep/Motorcraft distributor (Reman) for about $50 from the parts store,
It will come in the correct housing length housing, (most HEI's for V-8s DO NOT)
It will come with the correct drive gear, so the drive gear won't be an issue like many of the HEI distributors have issues with gears,
And it's off the shelf for cheap, usually around $50. '79 Jeep with AMC 304 V-8 engine when you order.
The small Jeep type distributor cap and rotor right on the advance weights is solved by using the cap adapter, cap and rotor from a '79 Ford F-AMC 150 Pickup.
That cap adapter, cap and rotor will drop right on your Jeep/Motorcraft distributor.
The taller rotor gets the spark energy up and away from the distributor shaft/housing/advance weights so it doesn't 'Ground' fire,
And the wider cap keeps cross fire to the wrong terminal down with the increased spark energy the electronic ignition is going to produce.
------------------
For a module, you have some choices,
From a $20 GM style HEI module to a $200 CDI module which is a 600% to 1,000% increase in spark energy, depending on your top RPM.
The $20-$25 module works fine for most applications,
Is available everywhere right off the shelf so you are never stranded waiting for a replacement module to come in,
And it's fairly easy to install, but you will have to do some wiring.
---------------------
Ignition coils are cheap,
With an HEI style module or CDI module, the Ford E-core coil from a salvage yard works VERY WELL for this application.
Ford used a top quality E-core coil from about '86 until the late 90's in about everything, they are all over the salvage yards,
And you can pick the coil, coil connector, wiring pigtail and bracket up for about $10.
If you buy one new, it's going to run you about $60 for the ignition coil, about $15 for the coil connector at NAPA,
And you can't buy the bracket on the aftermarket...
So a trip to the local 'U Pull' salvage yard is well worth your time if you are low on cash, and you can't really buy a higher quality coil anywhere with the exception of MSD for about $70.
-----------------------------------
Spark plug wires are a HUGE deal that most people overlook entirely...
They buy the cheapest thing off the shelf, then complain the ignition isn't doing what they think it should....
MSD makes a cut to fit wire set for about $80 that works GREAT, and they are exactly the correct length since you cut them yourself and install the cap terminal boots on the wires.
The plug terminals come straight, but will bend up to 90 degrees (and beyond) so you get a PRECISE fit,
The terminals are stainless steel with a SNAP LOCK into place,
And with a little dielectric grease, the plug wires/boots will run under water.
MSD also makes a set of AMC V-8 wires that are direct install, but they won't fit as well as ones you make up yourself...
--------------------------------------------------
Another option is to convert that breaker points distributor over to electronic ignition, and there are a few companies that make a conversion kit.
The problem with those conversions is they are proprietary, and if something goes wrong, you are stuck a week or two for a replacement,
Or you spend a month or two waiting for a 'Warranty' that might, or might not show up.
--------------------------
For right now,
1. Connect your test light to the battery POSITIVE terminal,
Probe the negative terminal to make sure it works.
2. Disconnect the distributor wire from the ignition coil.
3. Probe the DISCONNECTED distributor wire terminal while someone cranks the engine.
You should get a 'Flashing'.
If you DO NOT get a flashing, then the breaker points are not functioning.
Time for new breaker points or a cleaning, filing and adjustment of your current breaker points.
If you DO get a fairly even flashing,
Then move to the next step.
4. Remove the coil POSITIVE wire, usually 'Red',
5. Switch your test light connection to the battery NEGATIVE terminal, test against the battery Positive post to make sure you have a good connection,
6. Then probe the WIRE that was hooked to the coil positive terminal,
With the key swith in the 'Run' position, you should get a 'Light' at the tester.
If you DO NOT get a light at the tester,
It's probably a bad ignition fuse, bad ignition switch, bad factory tach, or the ignition resistor that should be hooked to the wire you are testing that feeds the ignition coil.
7. If you DO get a light with the key switch in the 'Run' position,
Then continue to probe that wire while someone cranks the engine for you.
You should get a 'Bright Light' when the engine cranks.
If you do NOT get a light at the tester when cranking,
Then someone did NOT install the correct starter relay and jumper wire between starter relay and ignition coil.
Does any of this make sense?
When you say looks like a 'Top' that leads me to believe someone has swapped out your Prestolite and swapped in a Delco Remy Breaker Point distributor.
If there is one wire that goes directly to the ignition coil negative terminal,
Then it's a breaker point distributor, probably a Delco Remy version, which isn't too bad to upgrade to electronic ignition...
What usually happens with the breaker point ignitions is, the top bushing wears out and you wind up with a Dwell angle that won't support the spark cycle.
--------------------
You have two or three choices, depends on your wallet and skill level...
One is an aftermarket HEI distributor, which I DO NOT recommend for a V-8 engine.
A HEI that is trustworty will run you $300+ (and about $100 more for good plug wires, cheap wires and HEI's don't get along at all).
HEI distributors also get in the way of the power steering pump, which is a HUGE pain in the azz when you go to install.
----
The second choice, and the one I recommend,
Is a factory Jeep/Motorcraft distributor (Reman) for about $50 from the parts store,
It will come in the correct housing length housing, (most HEI's for V-8s DO NOT)
It will come with the correct drive gear, so the drive gear won't be an issue like many of the HEI distributors have issues with gears,
And it's off the shelf for cheap, usually around $50. '79 Jeep with AMC 304 V-8 engine when you order.
The small Jeep type distributor cap and rotor right on the advance weights is solved by using the cap adapter, cap and rotor from a '79 Ford F-AMC 150 Pickup.
That cap adapter, cap and rotor will drop right on your Jeep/Motorcraft distributor.
The taller rotor gets the spark energy up and away from the distributor shaft/housing/advance weights so it doesn't 'Ground' fire,
And the wider cap keeps cross fire to the wrong terminal down with the increased spark energy the electronic ignition is going to produce.
------------------
For a module, you have some choices,
From a $20 GM style HEI module to a $200 CDI module which is a 600% to 1,000% increase in spark energy, depending on your top RPM.
The $20-$25 module works fine for most applications,
Is available everywhere right off the shelf so you are never stranded waiting for a replacement module to come in,
And it's fairly easy to install, but you will have to do some wiring.
---------------------
Ignition coils are cheap,
With an HEI style module or CDI module, the Ford E-core coil from a salvage yard works VERY WELL for this application.
Ford used a top quality E-core coil from about '86 until the late 90's in about everything, they are all over the salvage yards,
And you can pick the coil, coil connector, wiring pigtail and bracket up for about $10.
If you buy one new, it's going to run you about $60 for the ignition coil, about $15 for the coil connector at NAPA,
And you can't buy the bracket on the aftermarket...
So a trip to the local 'U Pull' salvage yard is well worth your time if you are low on cash, and you can't really buy a higher quality coil anywhere with the exception of MSD for about $70.
-----------------------------------
Spark plug wires are a HUGE deal that most people overlook entirely...
They buy the cheapest thing off the shelf, then complain the ignition isn't doing what they think it should....
MSD makes a cut to fit wire set for about $80 that works GREAT, and they are exactly the correct length since you cut them yourself and install the cap terminal boots on the wires.
The plug terminals come straight, but will bend up to 90 degrees (and beyond) so you get a PRECISE fit,
The terminals are stainless steel with a SNAP LOCK into place,
And with a little dielectric grease, the plug wires/boots will run under water.
MSD also makes a set of AMC V-8 wires that are direct install, but they won't fit as well as ones you make up yourself...
--------------------------------------------------
Another option is to convert that breaker points distributor over to electronic ignition, and there are a few companies that make a conversion kit.
The problem with those conversions is they are proprietary, and if something goes wrong, you are stuck a week or two for a replacement,
Or you spend a month or two waiting for a 'Warranty' that might, or might not show up.
--------------------------
For right now,
1. Connect your test light to the battery POSITIVE terminal,
Probe the negative terminal to make sure it works.
2. Disconnect the distributor wire from the ignition coil.
3. Probe the DISCONNECTED distributor wire terminal while someone cranks the engine.
You should get a 'Flashing'.
If you DO NOT get a flashing, then the breaker points are not functioning.
Time for new breaker points or a cleaning, filing and adjustment of your current breaker points.
If you DO get a fairly even flashing,
Then move to the next step.
4. Remove the coil POSITIVE wire, usually 'Red',
5. Switch your test light connection to the battery NEGATIVE terminal, test against the battery Positive post to make sure you have a good connection,
6. Then probe the WIRE that was hooked to the coil positive terminal,
With the key swith in the 'Run' position, you should get a 'Light' at the tester.
If you DO NOT get a light at the tester,
It's probably a bad ignition fuse, bad ignition switch, bad factory tach, or the ignition resistor that should be hooked to the wire you are testing that feeds the ignition coil.
7. If you DO get a light with the key switch in the 'Run' position,
Then continue to probe that wire while someone cranks the engine for you.
You should get a 'Bright Light' when the engine cranks.
If you do NOT get a light at the tester when cranking,
Then someone did NOT install the correct starter relay and jumper wire between starter relay and ignition coil.
Does any of this make sense?
red75cj5
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- i have a 75 cj5 with a stock amc 304, t case front and rear diffs as well
the vacuum advance dose NOT look like a top, it has what looks like 2 o's next to each other.ok thanks for all of the info!! i will try the first test that you said to do! i have already done the seconed one. should i be getting power out of the igintion control module to the distributor
TeamRush
Active Jeeper
The two 'O's next to each other is a Prestolite system.
The vacuum advance will be plastic.
You need to test the coil and the module, make sure both are getting power.
You need to make sure the module is getting 'Ground' (a single wire from module to fender which really needs a dedicated ground wire attached to it)
And you need to make sure the distributor is getting signal to the module connector,
And the connection between coil and module is working.
The vacuum advance will be plastic.
You need to test the coil and the module, make sure both are getting power.
You need to make sure the module is getting 'Ground' (a single wire from module to fender which really needs a dedicated ground wire attached to it)
And you need to make sure the distributor is getting signal to the module connector,
And the connection between coil and module is working.
red75cj5
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- i have a 75 cj5 with a stock amc 304, t case front and rear diffs as well
I know that the coil is getting power. i am pretty sure that the module is getting power, i tested the the female side of the plug that it plugs into and there is power to it. know does the distributor get power from the module or does the module send the power to the distributor?
Now knowing that it is a prestolite what would be the best thing to switch it to? price rang $75-200. i would much rather just change it out and get something better and more reliable!!
Now knowing that it is a prestolite what would be the best thing to switch it to? price rang $75-200. i would much rather just change it out and get something better and more reliable!!
TeamRush
Active Jeeper
The ignition switch feeds both the coil and module off the same wire.
-----------------------
You are going to be hard pressed to swap to anything really reliable for $200 since the plug wires alone are going to run close to $100...
And if you use 'Cheap' plug wires, you are wasting time and money.
The 'Easiest' replacement is an GM style HEI clone.
Runs about $300 for the distributor alone, then you still have to get reasonable plug wires, which I wouldn't call the wires sold with most 'Safe' HEI clones 'Reasonable'...
--------------
A MODULAR SYSTEM THAT LETS YOU UPGRADE EVERY PART OF THE IGNITION...
The most 'Safe',
The most expandable,
The most updated system is a Jeep/Motorcraft distributor from a '78 to '83 CJ with V-8 engine.
Runs about $50 at the parts stores.
Now, the HEI guys will tell you these distributors are 'Junk',
But they usually have a dog in the fight, trying to sell you something,
Or they are 'Fan Boys' and don't have a grasp on side by side comparing of the two distributors...
The Jeep/Motorcraft distributor is more tuneable than the actual GM HEI from the factory,
It's more reliable because of better design from the factory,
And it's got a much stronger trigger signal than the HEI's from the factory.
It's all around a very good choice for the price ($50 for a parts store reman) and will work very well.
----
Then you will have to shell out between $35-$40 for a cap adapter, cap, rotor to Upgrade that distributor to electronic ignition output voltages/amperage.
Summit Racing sells an MSD kit, Cap Adapter, Cap, Rotor for about $36 with a VERY GOOD (MSD) distributor cap.
About the best cap on the market for non racing applications.
That pretty much completes the distributor for install.
MSD plug wires top off the high voltage side, and they work GREAT for this application. They run about $80 a set, but you will run them for several years with no problems.
Mine have been installed and running the worst environments you can think of for 6 or 7 years with ZERO issues.
-----------------
The ignition coil needs to be compatible with the module.
If you run a $25 GM HEI style module, which is fine in most applications,
You need to run an 'E-core' style coil.
The HEI style modules from the discount stores are designed and built to work with E-core coils.
The HEI style module is just flat more reliable than the aftermarket proprietary modules or the aftermarket/parts store DuraSpark module replacements,
And another plus is, it's cheaper and grows on trees at any parts store.
Let me get my new computer up and running and I'll post some pictures.
-----------------------
You are going to be hard pressed to swap to anything really reliable for $200 since the plug wires alone are going to run close to $100...
And if you use 'Cheap' plug wires, you are wasting time and money.
The 'Easiest' replacement is an GM style HEI clone.
Runs about $300 for the distributor alone, then you still have to get reasonable plug wires, which I wouldn't call the wires sold with most 'Safe' HEI clones 'Reasonable'...
--------------
A MODULAR SYSTEM THAT LETS YOU UPGRADE EVERY PART OF THE IGNITION...
The most 'Safe',
The most expandable,
The most updated system is a Jeep/Motorcraft distributor from a '78 to '83 CJ with V-8 engine.
Runs about $50 at the parts stores.
Now, the HEI guys will tell you these distributors are 'Junk',
But they usually have a dog in the fight, trying to sell you something,
Or they are 'Fan Boys' and don't have a grasp on side by side comparing of the two distributors...
The Jeep/Motorcraft distributor is more tuneable than the actual GM HEI from the factory,
It's more reliable because of better design from the factory,
And it's got a much stronger trigger signal than the HEI's from the factory.
It's all around a very good choice for the price ($50 for a parts store reman) and will work very well.
----
Then you will have to shell out between $35-$40 for a cap adapter, cap, rotor to Upgrade that distributor to electronic ignition output voltages/amperage.
Summit Racing sells an MSD kit, Cap Adapter, Cap, Rotor for about $36 with a VERY GOOD (MSD) distributor cap.
About the best cap on the market for non racing applications.
That pretty much completes the distributor for install.
MSD plug wires top off the high voltage side, and they work GREAT for this application. They run about $80 a set, but you will run them for several years with no problems.
Mine have been installed and running the worst environments you can think of for 6 or 7 years with ZERO issues.
-----------------
The ignition coil needs to be compatible with the module.
If you run a $25 GM HEI style module, which is fine in most applications,
You need to run an 'E-core' style coil.
The HEI style modules from the discount stores are designed and built to work with E-core coils.
The HEI style module is just flat more reliable than the aftermarket proprietary modules or the aftermarket/parts store DuraSpark module replacements,
And another plus is, it's cheaper and grows on trees at any parts store.
Let me get my new computer up and running and I'll post some pictures.
red75cj5
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- i have a 75 cj5 with a stock amc 304, t case front and rear diffs as well
ok so here is what i got.
stock 79 distributor
cap adapter and cap and rotor
accell super coil
stock 79 module
msd plug wires
all of these i bought braind new.
i looked and some wire diagrams to see how to wire it all up. i just want to make sure that i have this all right.
3 wires from the module to distributor
1 wire from the module to coil minus side
1 wire from the module to coil plus side
1 wire from module to the I side of the starter solinoed
stock 79 distributor
cap adapter and cap and rotor
accell super coil
stock 79 module
msd plug wires
all of these i bought braind new.
i looked and some wire diagrams to see how to wire it all up. i just want to make sure that i have this all right.
3 wires from the module to distributor
1 wire from the module to coil minus side
1 wire from the module to coil plus side
1 wire from module to the I side of the starter solinoed