I have a Denso alternator which was checked out by our only surviving local rebuilder as having "plenty of power". When I put a analog meter on the alternator output wire using a shunt I saw the rapid flicker that I have been seeing in my volt meter and lights. My gauge lights and headlights flicker at idle. I get a miss at very low idle when warm.

The car is my 64 Dart, auto. I have done the amp meter bypass, alternator upgrade and headlight upgrade. I have run grounds directly back to to the battery for the HEI, Alt, VR, lights. I have wired the alternator output wire to the bat + with a 4G and fuse. The VR feed is via a relay as is the HEI feed and the headlights are on 2 relays.

With the shunt installed and the system hooked up normal including the VR I see 14.4 volts with a flicker of may be .5 volts. At idle around 600 RPM the Alt is putting out 14-15 amps. When I turn on the lights and heater blower it goes up to 36 amps. The voltage stays at 14.4. When I put a load on the system with a battery load tester (momentary) at idle the amperage climbs to 90+ but the voltage drops to 13 volts. I did not leave the load test on long enough to see what the voltage did at higher RPMs.

Is 14 amps enough to run the HEI? Could the voltage flicker be affecting the HEI (miss at low idle)?

I feel like there is plenty of amperage as it responds smoothly to increased load. The VR is holding the voltage. The battery, alternator and VR are relatively new. The car runs excellent except at low idle when warm. I hate to start replacing the alternator and VR and battery just for this flicker.

2 other questions.

How do I full field the Denso with the two field wires. I run the 2 wire VR.

Where of I hook up the lead for the RPM test on the HEI?

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64 Dart GT Convertible, 225 Super 6, Carter BBD, 14x7 SBP Rally Wheels, HEI, Fuel mod, wiring upgrade, Alt upgrade, 2BBL, headlight upgrade, front disc brake conversion

Obviously the HEI works at cranking voltage and RPM so with the engine running I believe the ignition system has plenty of power.

This sounds like a voltage regulator or grounding problem.

How big a ground do you have between the engine and the battery? If the battery ground cable is well connected to the block and the alternator is well grounded through it's mounting (I've had problems here) that should be fine.

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Joshua

You full-field the Denso alternator by removing the two field wires, grounding one field terminal, and connecting the other field terminal to the B+ (output) terminal. Don't rev it -- idle only!

What (exact, specific) regulator are you running? Have you run a ground wire from alternator housing to (unpainted) regulator base and from (unpainted) regulator base to battery negative?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The voltage regulator is a NAPA brand I will have to look up the part number. I don't remember exactly how I sourced that part. I think the alternator is a 90 amp model. I thought the VRs all work about the same. I have been through quite a few alternators and VRs over the years and never fully resolved this issue.

The VR is the two wire style with the VR power wire connecting to both the VR and the alternator and a second wire from the VR to the second field connector. It has the triangular plug on the font with one green and one blue wire. I have a spare VR which I will substitute in today. The VR is relocated to the fender near the Alt.

There is a ground directly from the VR housing to the Alt case. From the same point on the Alt case a 10G ground wire runs directly to the battery. There are additional ground wires from a radiator mounting bolt to the battery neg and from the firewall ground where the head ground strap connects. The HEI is also grounded directly to the battery. I also ran an additional ground for the instrument panel and stereo to that firewall point. The main ground from the battery to the engine block has been cleaned and the wire replaced.

I have checked the grounding at each of these enhanced grounding cites and to the appliances and not found significant drops. Nothing as high as a 0.1 volt. A few hundredths. I will do those checks again today.

I have (perhaps mis placed) confidence in my belt and suspender grounds. I do not solder all my wire connections but I crimp and shrink tube them. I use electronic cleaner and a wire brush to assure good connections. I put a thin film of Ox Guard on the grounds.

I have replaced the floor switch for the headlight high low and the light switch. I have replaced the turn signal switch in the column and cleaned the grounds to the tail lights.

My fuel and temp gauges read correctly. When i checked my sender for the fuel tank I saw the blinking voltage from the voltage regulator. I think all that is working correctly.

The power ( all via relays) for my VR, headlights, and HEI comes from the fuse terminal of the maxi fuse I run on the 4 gauge wire between the Alt + and the battery +. That means those power sources are closer to alternator than the battery but connected to the battery with a 4 g wire.

I have not replaced the fusible link. Not much goes through there now. i have never found the master soldered connection.

I remember Dan's comment from years ago about a feedback loop he called rinse-lather-repeat (maybe dan still has hair) which I think referred to poor grounding to the VR leading to unstable voltage control from the VR, magnifying the pulse. So I ran the VR power directly from the battery via a relay and grounded the VR directly to the alternator case and the battery.

No one is saying anything about a alternator diode or brush problem. I feel like I am seeing both output and voltage regulation working properly. As I had said when I had the Alt checkout specifically because of this issue my local re-builder did not think it was the Alt. The battery is a 3 yo Costco. It tests out under load but not to the top of the range.

Anything else?

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64 Dart GT Convertible, 225 Super 6, Carter BBD, 14x7 SBP Rally Wheels, HEI, Fuel mod, wiring upgrade, Alt upgrade, 2BBL, headlight upgrade, front disc brake conversion

I am using the NAPA Echlin VR 38. I think that is what the 71 and up systems used. I see that there are VRs advertised for high output Denso alternators. There aren't any numbers on my alternator but it put out 90+ amps under load. Would that overload this VR 38?

I hooked up a tach on my HEI at the green wire to the coil. my gauge had a High RPM and Low RPM setting. On the low setting the tach bounced around pretty dramatically. At the high RPM it twitched like the voltage around 900 RPM at idle and in gear (auto). Does the tach bouncing indicate a bad coil or HEI unit? I hate to start replacing electrical parts. Except for the idle it runs really well.

At idle when I put the lights and blinkers on the voltage twitch is very noticeable of about a volt. My previous tests showed about 14 amps at idle with no load. The amp output came up with increased load. The VR keeps the voltage in range, to the high side 14.5 dropping down a volt under load.

I had an issue where my Alt. keeped over charging because of my VR not properly grounding. Even after replacing all the wires, connectors, and grounds in the charging/starting circuit I had the same issue. My fix was replacing the the Alt with a Powermaster one wire Alt. I dont know if these VR nowadays or just junk or if there is a method for your set up. This was just my experience.

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~Nic

After reviewing the HEI blog I am wondering whether my spiky voltage has damaged my HEI module and or coil. Those are slightly spendy components to replace. But the symtoms of missing (poping) at low idle, stall when warm are mentioned.

I did the HEI several years ago, but not many miles. I used the NAPA TP45 ECU and I think I used the (cheaper) FD 478 coil. I found the coil ECU bracket and heat sink in the wrecking yard and mounted a new coil and ECU. I ran a relay for the power and an extra ground to the HEI mounting bracket.

As I said above, whenI hook up a tach to where the green coil wire attaches to the ECU it bounces around. I am not sure whether that is just the voltage tick or whether the ECU and or coil might be bad.

The FD 478X coil is around $75 and a new ECU is around $45. So I hate to replace those if I am still seeing this voltage flutter.

I have been suspecting the alternator because when I take the belt off the alternator the voltage twitch goes away.

I have not hooked up a tach with the belt off.

Any suggestions on how to trouble shoot the ignition or what order to replace VR, ECU and Coil?

Try checking the voltage at the alternator terminal (engine running), with the volt meter set for A/C. If you are reading more then about one tenth (.1) of a volt A/C the alternator has a bad diode(s).

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

When I tried to check the AC output as Charrlie S suggested my better quality multimeter (Extech 410) was not working and the cheapo seemed to be giving me a reading of 35. So I was reading it wrong or not did not have it set up. I changed out my alternator and VR with some spares I had. Nothing changed I still had a miss and voltage flutter.

It turns out that the new battery I had put in my multimeter was bad and nearly dead, giving me numbers but wild numbers. The old, bad new part syndrome. When I put a good battery in and checked the AC output it was between .05 and .1. That is on my reserve alternator.


I will start a new topic on the mechanical tests I did. There is a mechanical problem which I think is a sticking valve. I will post what I found.

Thanks for the help on the electrical. It is not resolved but it may be that the miss at low RPM is causing enough voltage twitch to show up in the lights. On Dans site he notes how a small voltage difference makes a big difference in lumen output.