1968 Firebird, Pontiac 350, 4 speed, no AC. Pertronix Ignitor 3 dizzy - seems to be part # D7120700 Prior owner purchased in 2012
Issue: All is well, idle ~ 650 in neutral at a stop. Without warning, rpm drops to ~ 400. I need to goose the gas to ~ 1100-1200 to keep it running. Just as fast all goes back to normal.
Last fall, put a timing light on it. Loosen dizzy to set timing. Don't recall exacts, but was running good. Tighten dizzy while car was running and it started to stumble. Thought I'd moved dizzy. Timing light was non functional, no strobe. Timing light wires were good, not in the way. Press trigger again, light works and stumble is gone. This continued, off and on, for some time before I gave up.
Took it to a local trusted mechanic. He had same results. Put a spark tester on #1, Intermittent no spark. R&R plugs, wires, coil - issue still exists. He claimed, when issue arises, there is less than 12v to the coil. At this point, drove it home w/no issue. Packed it away for winter.
Yesterday, started to dig into wiring. The more I dig, the more old wires I find. I think I might be better off running new, but got minimal clue on right way to do it. Based on past posts here, I should not use existing wires and fuse box.
Maybe some more history, how long have you owned the car? Has this been a problem since you've owned it or did it suddenly develop last fall?
Well you replaced the plugs, plug wires and coil. What about the distributor cap and rotor? Sometimes the cap will develop a carbon track and the juice will follow the track resulting in a miss fire.
Try putting the timing light on the other plug wires to check if they are firing intermittently as well. If all the plugs are firing correctly except number one I would suspect the plug, wire or cap/rotor. If they are all firing intermittently I would suspect the plugs, wires, rotor/cap and module. Although I've found the module either works or doesn't. But if you have replaced the plugs, wires and coil you can concentrate on the cap and rotor or the wiring to the distributor.
Is the distributor an HEI? If so it will require 12-14.5 volts to operate correctly. If originality is not and issue I suggest installing a relay/solenoid to power the distributor. Use the ignition switched wire to turn the solenoid off and on and power the distributor through the solenoid from the battery or the alternator.
If the car has to look original you may have to replace the wire powering the distributor from the ignition switch. Originally they were a resistor wire and only supplied the points distributor with about nine volts after it started.
The condition of the wires and connections may be the fault as well. Any corrosion at a connection will result in a voltage drop across the connection/splice. If the wiring to the distributor has some crimped butt splices, that could be the source of the voltage drop. Better to crimp, solder then heat shrink the joints.
Maybe some more history, how long have you owned the car? Has this been a problem since you've owned it or did it suddenly develop last fall?
Well you replaced the plugs, plug wires and coil. What about the distributor cap and rotor? Sometimes the cap will develop a carbon track and the juice will follow the track resulting in a miss fire.
Try putting the timing light on the other plug wires to check if they are firing intermittently as well. If all the plugs are firing correctly except number one I would suspect the plug, wire or cap/rotor. If they are all firing intermittently I would suspect the plugs, wires, rotor/cap and module. Although I've found the module either works or doesn't. But if you have replaced the plugs, wires and coil you can concentrate on the cap and rotor or the wiring to the distributor.
Is the distributor an HEI? If so it will require 12-14.5 volts to operate correctly. If originality is not and issue I suggest installing a relay/solenoid to power the distributor. Use the ignition switched wire to turn the solenoid off and on and power the distributor through the solenoid from the battery or the alternator.
If the car has to look original you may have to replace the wire powering the distributor from the ignition switch. Originally they were a resistor wire and only supplied the points distributor with about nine volts after it started.
The condition of the wires and connections may be the fault as well. Any corrosion at a connection will result in a voltage drop across the connection/splice. If the wiring to the distributor has some crimped butt splices, that could be the source of the voltage drop. Better to crimp, solder then heat shrink the joints.
Found some time to investigate, do some work.
Bought the car in Apr 2016 for our 40th wedding anniversary. Not totally done, but (almost) turn key. Pontiac 350, edelbrock carb, 4 speed. Needs rockers but we like it. Been working thru the issues as we find them.
Resolved overheating issue thanks to this site.
It's always idled rough. According to the paperwork I was given, it has a Comp Cams part # 51-116-3, lift = 516/516. I thought the idle was normal, cam related. It has good power once it gets moving. Heavy gas smell out the exhaust. Maybe 7mpg. I get better mpg w/my 70 GMC big block.
I figured it needed a tune up, check plugs to see if its running rich. All plugs looked great. #1 & #3 plug wires had rust inside the boot. R&R plugs and wires, gap = 045 for pertronix HEI. Went to time it, noticed the intermittent spark.
I read your reply, last part about the wiring. I found lots of crimped connections, a guillotine crimp in the distributor power wire. I pulled the distributor to solder additional 16ga wire and a ring connector. R&R'ed crimp connections for electric choke on the carb, connection for in hood tach. I firmly believe the guillotine connector for the distributor is (was?) my problem. It looked like not many strands were left.
Put it all back together. All she wants to do is back fire out the carb. Im thinking timing but I do not recall which way to turn. I work alone, 911 is a 10 minute wait, carb fires bother me. Had a bad one long time ago. Aint that young anymore(smile).
Funny you should mention carb fires, I had one yesterday that heated up the open hood, didn't want to cover the thing with fire extinguisher dust and it wouldn't ingest itself by continuing to crank the starter. I had to throw a pair of welding gloves on top to put it out.
It does sound like you have some plug wires on incorrectly or when you stabbed the distributor back in you missed it by a tooth or so. Did you put the crankshaft in the #1 piston top dead center, compression stroke position before you pulled the distributor? Maybe check the plug wires just to be sure they are on the correct plugs. Firing order is 18436572. If the plugs are all where they belong you may have gotten the distributor back on a camshaft tooth over one way or the other..Pull the # 1 plug and turn the engine by hand (socket on the crankshaft nut and a long handled ratchet or breaker bar) until the mark on the damper is approaching the timing marks on the front cover. Put your finger over the plug hole and check that it is in compression not exhaust stroke. Set the crankshaft to top dead center on compression stroke # 1 cylinder. Mark the distributor housing just below #1 wire tower with a felt pen or piece of chalk. Take off the distributor cap and check if the rotor is pointing to where #1 terminal mark is.. If it isn't loosen the distributor and turn until the rotor is pointing to the position of the #1 mark. If you can't turn it to the mark because it is hitting the firewall or head then you can change the position of the wires in the cap to match the rotor or pull the distributor and reinstall it so the rotor ends up pointing to your mark. I like to turn the distributor so the rotor is pointing to a point just before the mark, that will get you close to the correct advance for starting, Then it's a matter of starting the engine and turning the distributor to get it at the correct timing.
Remember, the rotor is tuning counter clockwise as viewed from the top. To advance you move the distributor clockwise to retard it's CCW.
Hmm, I wonder if those that have only seen digital timepieces, such as on there cell phones, would know what clockwise is?
Trust me when I say, Im old enough to know CCW vs. CW(big grin). Firing order same as my GMC. Did not know CCW for Pontiac.
I did find #2 & #4 swapped, has been fixed. Thank you ped and BB428!!
Ran better but still seemed off. I found this link.... https://firstgenfirebird.org/forums...p;Words=don-t&Search=true#Post317504 I re-stabbed distributor, CCW 1 tooth. Vacuum can now sits between the heater hose and carb. Fired up, idled better, actually ran decent on a 8 mile road trip. Shut it down, waited a second or 2, tried an immediate start. Took 3 or so revolutions before she fired.
I think I still need to play with the timing, it's got a shudder now and again at idle.
Edelbrock carb is next to tweak. While it's much better than before, still have a fuel smelling exhaust. Might be connected to the slow start on refire after road trip? Never played with an Edlebrock.
Thank you. Very much appreciated....don t.
PS.... I had a bucket of water and a damp rag in case of a carb fire. Never happened.
Ah the old stinky clothes syndrome. I have a friend down in Houston who stunk the place up with his 455 Olds and Edelbrock. He tried all the tricks, drilling holes in the butterflies etc. All he did was ruin a good carb. He put on a big 950 Holley and fumigates the streets when he drives around. Unless the carb is completely wrong for the application pretty much all the most common carbs can be correctly tuned for your car. Including the Edelbrock, which is a Carter AFB, made by Weber USA, with an Edelbrock sticker on it. Just a methodical step by step procedure.
What model number is your Edelbrock?
I find most rich conditions with the E carbs are float setting, choke or needle and seat. Any/all of these not right may cause too much gas going down the intake. I would first set the float level to spec, and make sure the needle and seat are free of debris, then set the choke is correctly. After that it's setting the mixture correctly. Warm the engine then set the idle speed to your target idle speed, slowly turn one mixture screw in or out to get the highest rpm, reset idle mixture then turn the other screw until you get the highest rpm, and once again set idle speed. Keep going from one to the other until you get the highest speed from your mixture screws., then turn both screw in to get a slight drop in rpm, 20-30 rpm, that will be your best lean idle. Turning the mixture screws in leans the mixture, out richens it. You can use a vacuum gauge as well, use the same procedure to obtain the highest vacuum.
If you still have a smelly exhaust you may have to change the rods, needles or springs.
I had to play with mine when I first got it. The motor was rebuilt at some point, when some one changed the intake to a four barrel from a two barrel. They added a cam durning the rebuild, purchased a E carb to go on it with no adjusting of any kind. The car was running way to rich, pulled the carb, changed out the jets, rods and springs to a smaller set. The car runs a whole lot better, but I think I can still get it a little better just need to find the time.
1406, but that's neither here nor there at this point(smile).
Still had intermittent spark loss. Took it back to the trusted mechanic in town before I broke something. He found 2 issues.
1 - E choke on the carb was wired to the + on the coil. He wired it to a spade in the fuse box. This helped but did not 100% resolve the spark issue.
2 - New Pertronix dist (#D7120700). He told me the timing setting, but since I did not write them down, I no longer recall. While there he adjusted the carb. Said it was a minor tweak.
Wrote the check, Fired her up. Idle great, ran great. About a mile down the road I hear a rubbing noise. Driver side tail pipe fell off. Bunggie cord got me home, and to the exhaust shop. While at the exhaust shop, found 2 broke wheel studs(rear), which (fingers crossed) gets fixed this weekend.
Thanks for all your help. Much appreciated....don t.
You have one if those black clouds over you like the one that's been above my car since I bought it?
"Black cloud".... Nope but I am glad it's not my daily driver(smile). Then again, if it was my DD, Ida found time to fix it quicker than 4 months(grin). Nothing more than bumps in the road.....so far(fingers crossed grin).
Thanks much...have fun...don t.
PS... Removed wheel studs yesterday afternoon. Local part store had em in stock. Will get installed today. Fingers crossed, this afternoon, wife and I go out for some ice cream.
