Only cheap HEI works

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Tuff stuff performance in Cleveland makes a conversion kit I believe to change from the old regulator to the newer style.
 
68Valiant225 said:
Last night I went to put fuel in the 68, and after starting up easily and going about a block down the road, she started running really rough, like 1/4 throttle to keep it idling at less than 500 rpm. Limped back to the garage, hoping for a vacuum leak, or something obvious, didn't find anything. Eventually, I took off my brand new FBO ignition, and took the factory dizzy out, put in my $50 ebay HEI dizzy, ran perfect after I did that.
This is my second ignition box that I've had problems with, first a Mallory 690 box, now the FBO. I'm wondering if funky wiring in the car could be partially to blame. I'm running a squareback alternator, with one terminal grounded back to the case, and the voltage regulator that was on the car when I bough it. Is it possible that the charging system could be causing problems with the ignition system? My theory is that the nicer ignition boxes have tighter tolerances than the cheapo HEI, which is why the HEI works when the others don't.
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Not to derail this thread but are you saying MSD couldn't fix that junk assed 690 box they so lovingly slapped the Mallory name on?

I knew that would happen. Did you at least get a refund from that MSD junker?
 
yellow rose said:
Not to derail this thread but are you saying MSD couldn't fix that junk assed 690 box they so lovingly slapped the Mallory name on?

I knew that would happen. Did you at least get a refund from that MSD junker?
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They sure as hell couldn't fix it. Send it in 4 times and never got fixed. They never even replaced it. Every time I called the tech line, they got stumped because the box was broken and I actually had it wired right.
Ended up getting it refunded from summit, they were great to work with. Never buying MSD again
 
68Valiant225 said:
They sure as hell couldn't fix it. Send it in 4 times and never got fixed. They never even replaced it. Every time I called the tech line, they got stumped because the box was broken and I actually had it wired right.
Ended up getting it refunded from summit, they were great to work with. Never buying MSD again
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That's pisses me off. Somewhere on this very forum I said MSD was out to kill the Mallory brand, contrary to the talking head from MSD who said they wouldn't.

The very first thing I found was they changed the advance mechanism to the cheap GM style and I knew what else was coming.


Junky junk junk.

Thank GOD I have at least 3 full ignition systems on the bench with every two step and timing retard I could find. I still buy that stuff used when it comes along.

I've been pissing on MSD since 1978.

Ok, rant off before all the fan boys come along and tell me how good their MSD junk is.

My apologies for the derail, and I'm sorry you got screwed by MSD.
 
While 15 IS overcharging, it is not serious, and would not cause some ignition problem. Overcharging only has so many causes, in no particular order

1...Usually, voltage drop in the harness, including the ground path between regulator and battery NEG

2...Regulator going bad. Make sure engine is warmed and battery is "normalized" before making a decision on voltage. This is because some/ most regulators are temperature compensated, or at the very least, are sensitive to temperature. They normally run high when cold

3.....Certain battery problems can cause overcharging. Simple, usually, to swap in a known good battery

4...Other wiring problems

HOW TO CHECK for voltage drop problems

1....Hot side ....Turn key to "run" engine stopped. Stab one probe of your meter into the top of the battery POS post, and connect the remaining probe to the "igntion run" line as close to the VR as you can. You should read a very low voltage, the lower the better. More than about .3V check to find out why. Generally, bulkhead connector terminals, igntion switch connector / and switch itself, or bad connections at the ammeter.

2....Ground path. Run this two ways, with engine running "fast" to simulate low/ med speed cruise. First check with all acccessories off, and gain, with heater, lights, etc on. Stab one probe into the top of battery NEG post, and the other onto the VR mounting flange. You should read very little and zero is perfect

ANY DROP in the above two tests is ADDED to the VR set point, IE if the VR is "correct" at about 14v, and there is a 1 volt drop, the battery will "see" 15V
 
Thanks for the help! I'm gonna have to follow this up either mid next week, or in early December. I can't order in a voltage reg before I have to drive the car across the state, so since the car has been driving good on the hei, I'm going with the don't fix it if it aint broke method, just wanna get it 300 miles. Voltage regulator is definitely on the high priority list for Christmas break, though.
 
Either ignition system should run off the battery alone, i.e. 12.6 V when charged. The alternator's main purpose is to recharge the battery. Sure, you get a bit more ~14.3 V from the alternator, but not essential. Insure you get full battery voltage to the ignition box, or ballast resistor if it uses one. Check ground connections, which is the most common culprit. Don't rely on a rusty sheet-metal screw into the firewall as the factory design does.
 
I know this thread is super old, but I swapped the voltage reg over to the later model style, and still didn't have luck with the ignition working. Finally just bought a chinese NAPA ignition box and that worked, so I ran that for a while. I think when I was installing it I added a dedicated ground wire to the case. Eventually swapped the FBO box in with the intention of calling Don over there and getting it figured out, but it just ran right away. Ground seems to have made the difference
 
68Valiant225 said:
Last night I went to put fuel in the 68, and after starting up easily and going about a block down the road, she started running really rough, like 1/4 throttle to keep it idling at less than 500 rpm. Limped back to the garage, hoping for a vacuum leak, or something obvious, didn't find anything. Eventually, I took off my brand new FBO ignition, and took the factory dizzy out, put in my $50 ebay HEI dizzy, ran perfect after I did that.
This is my second ignition box that I've had problems with, first a Mallory 690 box, now the FBO. I'm wondering if funky wiring in the car could be partially to blame. I'm running a squareback alternator, with one terminal grounded back to the case, and the voltage regulator that was on the car when I bough it. Is it possible that the charging system could be causing problems with the ignition system? My theory is that the nicer ignition boxes have tighter tolerances than the cheapo HEI, which is why the HEI works when the others don't.
Click to expand...

EDIT: Just saw your last post.

Call Don at FBO (www.4secondsflat.com) and tell him about the box problem.
As long as your charging voltage doesn't go over 15v you should be fine there.
I'm sure he will help you with it.

FYI for other members the FBO system is made in the USA with some Mexico involvement.
NONE of it comes from China or any other Oriental manufacturer.
 
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