Ignition Coil Problem - Sputters, bogs down, and backfire when you step on the gas

[FFWalker]

I'm new to this forum, so any help would be greatly appreciated. I own a 1960 T-Bird Convertible with a 352. The car has sat for 10 years, but three months ago I got her started up and running.

So far I've replaced: radiator, surge tank, fuel pump, fuel filter, water pump, intake gasket, heater hoses, cap/rotor/points/condenser/plugs/wires, and all the fluids. No leaks from the engine.

The car runs great at idle and when I rev the engine. However, I took it out on the road and any time I step on the gas, it sputters and bogs down. If I give it more gas, it gets worse and backfires through the carb.

My first attempt at fixing this was replacing the original coil (50 years old) with a Pertronix flamethrower coil. This seemed to immediately solve my problems. I took the car for a two hour test drive (stop and go) with no issues.

Two days later, I started the car and had the exact same issue as before. The car runs smooth at idle, or if you drive the car and give it VERY little gas. However as soon as you give it more than 10%, it bogs down and sputters.

I've speculated that maybe it's the vacuum advance? I did pull the vacuum line from the carb to the distributor to check the vacuum, which there was some. Car runs a heck of a lot worse without that vacuum line, by the way...

Another guess was maybe my coil burnt out again. If that's the case, could it be the voltage regulator?

Any suggestions? I want to get this car on the road, where it belongs!

[jopizz]

At first I would suspect a fuel issue. Sounds like a bad accelerator pump in the carb but that doesn't explain it running fine when you replaced the coil. When you replaced all the ignition components did you recheck the timing. Also, after sitting for 10 years did you clean out the fuel tank or replace it. Old gas will turn to varnish and clog the carb passages in a short period of time. It may run fine at idle but will bog down under load. It could also be as simple as the choke not working or misadjusted.

[JohnG]

Coils rarely go bad; two in a row would be close to impossible. However, replacing the stock coil with the Pertronix was a great move! Just didn't happen to solve
your problem.

Voltage regulator is not an issue.

What did you do about the ballast resistor? What did the Pertronix instructions say? Leave it? bypass it?

At any rate, I'm with the jopizz on a fuel issue.

a) the line - at least blow it out with compressed air

b) the pump - check it's output.

c) some TBirds had a screen in the tank. Did you drain the tank out?? Ten years would have caused some bad s*&^ to form in the tank.

I like the idea of having a fuel pressure gauge on the line to the carb. Takes some of the mystery out of the whole deal. Kind of like a voltmeter. These only require about 4 psi. Summit sells them.

john

[FFWalker]

Fuel tank

Coils rarely go bad; two in a row would be close to impossible. However, replacing the stock coil with the Pertronix was a great move! Just didn't happen to solve
your problem.

What did you do about the ballast resistor? What did the Pertronix instructions say? Leave it? bypass it?

At any rate, I'm with the jopizz on a fuel issue.

a) the line - at least blow it out with compressed air

b) the pump - check it's output.

c) some TBirds had a screen in the tank. Did you drain the tank out?? Ten years would have caused some bad s*&^ to form in the tank.

I like the idea of having a fuel pressure gauge on the line to the carb. Takes some of the mystery out of the whole deal. Kind of like a voltmeter. These only require about 4 psi. Summit sells them.

john

Thank you for all the responses. Before I started the car, I drained the fuel tank (which was completely full for storage) and put new gas in. The sending unit's float was full of gas so I had to replace this as well, which gave me a chance to peak into the gas tank. Everything looked clean. Fuel pump is new and output has been tested. Line has been tested too. Fuel filter is new and tested as well.

I agree that coils rarely go bad, but I figured after 50 years anything was possible. I replaced the stock coil with a Pertronix at the suggestion of the T-Bird guy I ordered from. I told him I didn't want to mess with the wiring harness, and he said this bolted right in. The instructions say to remove it, but he said it would run fine "as is." Did I get bad advice?

To be honest, I wouldn't know where to find the ballast resistor in the wiring harness or even how it looks like. I can replace parts but I'm not very good with electrical.

The car did run fine as soon as the coil was replaced. It wasn't until the next time I drove it (two days later) that it started acting like it did before (sputter, backfire through the carb, and bog down).

[FFWalker]

Ballast resistor

I did some reading and found out that the '60 doesn't have a ballast resistor, but a resistor wire (pink) instead. I believe I found that at the firewall.

[Dakota Boy]

sounds like a carb issue to me. Did you take the carb apart and clean the heck out of it?

backfire is indicative of a lean condition I believe....

some junk stuck in the carb probably.

[Guest]

I would agree with the fuel problem after sitting for that long quite possibly some build up in the float bowl, maybe floating around and it cleared all be it coincidentally with the coil replacement. I would pull the carb and go through it. I had a holley that played up after sitting a while I had a mud wasp nest down the bowl breather.

Richard

[scumdog]

Maybe I'm wrong (again! you all say!) but it sounds like a 'lack of fuel' type problem - low fuel level in carb, blocked jet, weak accelerator pump.....

[JohnG]

On the ballast, I wasn't thinking - yes you have a resistor wire instead of the traditional ballast bolted to the fire wall.

I would contact Pertronix via their website and make it clear that a) you have points b) you have a Flamethrower and c) you have a resistance wire and want to be sure of what they recommend. (http://www.pertronix.com/support/ )

Since we're on ignitions, consider a first rate set of points from Accel. The BrandX that are in there may not survive as long with a different coil.

In any event, once set up correctly, you have improved the ignition area of your car considerably over the stock coil (if you still had the one with the mustard colored top, you can probably sell it to someone doing a "buy the book" restoration).

[simplyconnected]

We need a little more info.
Pull the distributor cap off and look inside at the towers. What does it look like inside the cap? Pictures work well, here.

Pull a spark plug out and watch it run in the dark (outside the engine). What does the spark look like (describe the color).

I agree with everything you guys said. Sounds like a possible fuel issue to me, but backfire can be from a timing issue. I had a rusty fuel tank that clogged the pickup screen; the engine would die, then fuel backwashed rust out of the pickup screen and it would work fine for awhile.

The fuel pressure gauge is a very good idea. If there is a fuel pump issue or a restriction before the gauge, your fuel pressure will drop to nothing. Don't rule out a loose fuel line fitting, allowing air to enter the fuel line. I like using a TEMPORARY clear vinyl hose so I can see the fuel.

What do the exhaust gasses look/smell like?
Did you inspect the points wire? Is the insulation good and the electrical connections tight? Don't forget to check your GROUND straps.

[scumdog]

And a wild card here - a too-hot coil can fry points. (although the resistor wire SHOULD prevent that).

[JohnG]

on the issue of the resistance wire, there is a short discussion from a couple of years ago at

http://www.squarebirds.org/vbulletin/showthread.php?t=5707&highlight=resistance+wire

and also at

http://www.squarebirds.org/vbulletin/showthread.php?t=3017&highlight=resistance+wire

Any and all grounds on an old car should be taken as suspect and overhauled. Between added paint, rust and other activity, they cannot be counted on. A little time with a file/sandpaper/Dremel can overcome this.

[tbird430]

What did the strainer "or sock" look like on your gas tanks sending unit?

Have you also checked to make sure the heat riser on the right exhasut manifold & pipe is OPEN and not stuck closed?

What is your timing set at anyways?

-Jon in TX.