Got a miss......

Silverback51 · #1 (**permalink**) 02-16-2008, 02:50 PM

......and it's driving me f*cking crazy.

So far I have replaced the MSD 6AL box, the tach adapter, plugs, and wires. Still misses. Get it up to around 3000 rpm and it's worse. Step into it a little and it's popping like a SOB. Oh, the tach bounces around like crazy. That's why I thought it was the box or the tach adapter. Nope, still the same.

It also sounds flat. Checked the timing yesterday and it took over 30 degrees of advance to get it to sound right, but it still ran like crap. No difference.

Pulled the distributor this morning to check it out. Wanted to make sure I had not sheared a pin. Nope, it's fine.

This is my first 385 series engine, so I'm still learning about them. Do they by chance have issues with the timing chains? I also remember reading somewhere that they can suffer from misfires if they sparkplug wires are close. Not sure what they meant by that.

Engine started life as a 460 crate motor. Original owner blew it up at around 2200 miles. He had it rebuilt and it's now got 5100 on it.

This started at the end of summer in that it would crap out a little if you got on it. Then it's just progressively gotten worse.

Any suggestions to look for will be greatly appreciated.

I have a new 460 crate motor sitting in the garage, and if I thought that would cure the problem I would put it in there. Just not sure if it's motor or electrical. Not sure if I have that much more electrical to change. I do have a new distributer in the box. Maybe I will change that out tomorrow also.

Thanks in advance.

ENTDOC · #2 (**permalink**) 02-16-2008, 02:59 PM

dist module

CHRIS DAMSCH · #3 (**permalink**) 02-16-2008, 03:00 PM

Check the cam gear teeth.

Silverback51 · #4 (**permalink**) 02-16-2008, 03:08 PM

Quote:

Originally Posted by ENTDOC

dist module

Is that within the distributor? The MSD box is brand new.

Silverback51 · #5 (**permalink**) 02-16-2008, 03:10 PM

Quote:

Originally Posted by CHRIS DAMSCH

Check the cam gear teeth.

Checked that this morning. Thought about that as it's got a hydraulic roller cam, and was afraid they may have used a cast gear on it. It's got a steel gear in great shape, so that wasn't it.

But thanks for idea.

RICK LAKE · #6 (**permalink**) 02-16-2008, 04:28 PM

Silverback51 Do you have a number and time to call you at this will take way too long from start to finish to write about this. Did the car run OK after the rebuild?? With the timing that far off, Is it possible the timing chain jumped a tooth or was not setup for cam and crank shaft timing. I you want to talk 732-254-3536 est time in the evenings. You could have a bad ground or power feed to the MSD system. If you have a new distributor install it and see if the same problem happens. Check to make sure the timing weights are moving inside and not locked out. Make sure the MSD was installed as per directions with power and ground going to the battery direct at a main connection. It could be a bad coil, the more load on the ign system it breaks down. I have heard and seen a couple of MSD coils crap out. Good luck Rick L. Get a spark tester to check for spark. with an MSD it should jump 1" and be bright. BECAREFULL THAT THING CAN KILL YOU WITH THE AMPS THEY PUT OUT. Rick L.

Silverback51 · #7 (**permalink**) 02-16-2008, 07:20 PM

Quote:

Originally Posted by RICK LAKE

Silverback51 Do you have a number and time to call you at this will take way too long from start to finish to write about this. Did the car run OK after the rebuild?? With the timing that far off, Is it possible the timing chain jumped a tooth or was not setup for cam and crank shaft timing. I you want to talk 732-254-3536 est time in the evenings. You could have a bad ground or power feed to the MSD system. If you have a new distributor install it and see if the same problem happens. Check to make sure the timing weights are moving inside and not locked out. Make sure the MSD was installed as per directions with power and ground going to the battery direct at a main connection. It could be a bad coil, the more load on the ign system it breaks down. I have heard and seen a couple of MSD coils crap out. Good luck Rick L. Get a spark tester to check for spark. with an MSD it should jump 1" and be bright. BECAREFULL THAT THING CAN KILL YOU WITH THE AMPS THEY PUT OUT. Rick L.

I forgot to mention that the coil, cap and rotor are all new also.

The MSD box is not hooked up to the battery. It picks up the positive power at the starter solinoid, and the negative is to a bolt in the back of the head. That is the way it was wired when I bought it, and it ran fine at that time.

I may do a quick patch wire job tomorrow to the battery and see if that makes a difference.

I have always hated electrical problems. It's frustrating as hell.

Thanks for the suggestions. I will check out a couple things and if no changes I will give you a call.

Thanks again.

CHRIS DAMSCH · #8 (**permalink**) 02-16-2008, 07:29 PM

Thought of something else. Check your ignition switch (where the key goes). I know mine went bad. Don't know if a contact in there would cause any of your problems.

Just a thought. I believe it's a Lucas product.

ENTDOC · #9 (**permalink**) 02-17-2008, 05:35 AM

the module is in the distributor and known to fail frequently

Rick Parker · #10 (**permalink**) 02-17-2008, 08:46 AM

IF you spliced (removed the OEM connectors) the wires from the distributor to the MSD box it is possible to have them connected incorrectly.

These wires are routed together in one harness to form the Magnetic
Pickup connector. The connector plugs directly into an MSD
Distributor or Crank Trigger. It will also connect to factory magnetic
pickups or other aftermarket pickups. The Violet wire is positive (+)
and the Green is negative (-). When these wires are used, the White
wire is not.

If the trigger wires are accidently reversed the timing will change dramatically and not allow the engine to run past about 4500rpm. My experience is that if the module within the distributor fails there will be no spark, caused by open circuit. Sometimes this is heat related, but it either allows spark or does not, it's generally not intermittant while running.

Silverback51 · #11 (**permalink**) 02-18-2008, 04:39 AM

Just wanted to thank everyone for their input regarding this.

Next weekend I'm going to run some new wiring back to the battery for both the Positive and Negative connections. Also going to remove the MSD wiring running to the distributor from the common wire bundle that it's currently in.

Just to make sure, I'm going to reinstall the original carburators on the car to ensure that the new carbs are not contributing to the problem. I'm sure that they are not, as the condition is the same prior to swapping them out.

Also going to disconnect the alternator. An old friend of mine said he ran across that once with a MSD. The alternator was spiking and causing all kinds of problems with the MSD. Didn't find it until they hooked it up on a scope and seen the alternator issue. Even then they did not relate it to the misfire. But they changed out the alternator and the misfire went away.

Anyway, thanks again. Your help has been greatly appreciated.

Silverback51 · #12 (**permalink**) 02-23-2008, 08:04 PM

Well after spending hundreds of dollars replacing the distributor, coil, plug wires, plugs, cap, rotor, tach adapter, and the MSD 6AL box, it turned out the be a $32.00 voltage regulator.

Today I rewired the entire system again. Still missed, so then I removed the fan belt and started it up. No miss. Replaced the alternator and then it missed again. Replaced the voltage regulator and magic happened. It ran fine.

I cannot believe how well it runs now. The new carbs are awsome. In second gear at 2500 RPM's I stepped into it at about half throttle. Broke the tires loose, and put a big **** eating grin on my face.

I'm in love again.

HI Cobra · #13 (**permalink**) 02-24-2008, 12:33 AM

Congratulations! I know that feeling - been there and done that before.

Rick Parker · #14 (**permalink**) 02-24-2008, 03:43 AM

Was this an old style regulator with field coils and relays, or newer replacements with transistorized circuitry? It must have been creating electrical RF "Noise" that was interfering with the MSD box. Glad you found it?

Silverback51 · #15 (**permalink**) 02-24-2008, 05:17 AM

Quote:

Originally Posted by Rick Parker

Was this an old style regulator with field coils and relays, or newer replacements with transistorized circuitry? It must have been creating electrical RF "Noise" that was interfering with the MSD box. Glad you found it?

I'm going to assume it's a newer replacement style as it's much smaller than the old style regulators I'm used to.

What was happening was the it was spiking the voltage. The guage had bounced all over ever since I had bought the car, so I was not really paying attention to it. Just assumed it was the gauge as the car ran fine. However yesterday it was much more pronounced. It was jumping from 0 to the 30-40 range. I'm assuming that these spikes were causing the MSD box to go crazy.