69 Pontiac Firebird HEI Distributor Question - Hot Rod Forum : Hotrodders Bulletin Board
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Old 11-24-2003, 05:54 PM
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Arrow 69 Pontiac Firebird HEI Distributor Question

Hello i installed a late 70's Hei Distributor. The distributor was said to be rebuilt and also curved for performance. First what exactly does this mean curved. Also i noticed when i turn the key the car does not start until i let the key go. I put a meter to the distributor and when the motor is cranking it is not gettig 12volts, its only when i let go that its getting power. Also i noticed i am getting sorta a vibration at high rpm's when accelerating. Could this problem be with the distributor. It idils fine and runs good, its only at high rpms and when accelerating. Any help would be great .

Thanks
John

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Old 11-24-2003, 06:21 PM
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pontiac69,

First the easy part. You will need to run a wire down to the starter solenoid and connect it to the "bat" terminal on the HEI. On the solenoid you will want to connect to the small post to the outside of the starter. This will give you 12v when you crank the engine and will allow the engine to start as soon as you crank it.

The "curved" term means that as the engine RPM goes up the mechanical advance keeps advancing along with the vacuum advance. This just allows you to put your heavy foot down and go very fast quick.

Good Luck
Scholman
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Old 11-24-2003, 09:20 PM
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Your ignition switch was designed for the points type ignition. Its possible that it has an "ignition bypass" built into it. What this means is during cranking it sends NO voltage to the distributor. Instead, when cranking, the solonoid will send 12 volts to the wire that feeds the distributor, but for the points distributor, it went to the distributor side of a balast resistor.

When cranking, 12 volts was needed to help fire off the cold engine. Once it started, you release the key, the solonoid wire went dead and the ign switch then sent 12 volts to the resistor, which cut it down to 6-8 volts running. This kept the coil from overheating and blowing up and kept the points from frying too early.

You can run the wire from the solonoid as stated in the previous post, or just find a good 12 volt "ACC" lead or terminal in the fuse box and go from there straight to the dist. The HEI needs full battey voltage to operate correctly. If you are only getting 6-8 volts at the HEI distributor now, it may be cutting out under a load and giving you that strange engine vibration.

Mark
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Old 11-25-2003, 12:30 AM
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While all the above replies are true and will work, a stock Pontiac ignition switch has "Ign 1" and "Ign 2" terminals. 1 is for normal running, and 2 is for starting. The wire to "Ign 2" is either broken or missing. Pontiac simply bridged these two terminals for their optional electronic ignition, and the same fix will work for HEI. This way, current will always pass through terminals 1 and 2. Now the wire for "Ign 2" was a resistor wire, and should have been replaced with a solid wire when the distributor was upgraded. To insure full voltage (and HEI demands full voltage and draws massive instantaneous current), I would run a new 10 gauge wire from the HEI and connect it to both ignition terminals at the switch.

The "vibration while accelerating" might be pre-ignition. Just make sure that you are not hearing pinging and rattling while on the gas. Whoever set up the distributor might have the advance curve coming in too soon. Some like to have the total advance in before 2,000 RPM, and with today's fuel, sometimes a much milder curve is needed. Maybe, maybe not, just listen closely to the engine.

Last edited by lust4speed; 11-25-2003 at 12:38 AM.
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Old 11-28-2003, 03:31 PM
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Thanks for all the help. It looks like all 3 of you are on the same page. I know im not getting any pinging or engine noise during acc. So i am assuming the distributor is not curved to much. I also know when idleing the distributor is getting 12 volts not 6-8 like a points type would need. I will have to test to see what the distributor is getting when i rev the engine. I wonder if at that point it is getting less than 12 volts. I know i will never be able to fing the ignition wires like talked about in the 3rd reply. I guess the only thing i can do is make sure i am getting a full 12 volts during idle and when the engine has load on it. I want to say im no mechanic just a backyard fixer upper that knows the basics plus around my bird. I guess my vibration could be a result of many things (rear, driveshaft, tires,etc) but i really belive it has something to do with the distributor since this vibration is only present during engine loads. I dont feel the vibration when crusing at a stead 50 mph , only when going 50mph and then putting the pedal to the metal do i feel the vibration. So i really think is a distributor or plug or wires problem. I think what i am going to do is purchase a distributor off ebay or somehting and replace the one i got just to see if its the distributor or not. I am looking to spend around 50bucks. Anything else you can tell me would be great thanks all.

Just thought of something else. What should my plug gap be. I remember someone saying to open the gap from what it was since it is now a hotter spark. Right now the plugs are set at 40. What plugs would you recommed running right now i have AC Delco plugs

Last edited by pontiac69; 11-28-2003 at 06:07 PM.
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Old 11-28-2003, 06:02 PM
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Here is what i just did:

Checked compression and all cylinders are running 150psi

Checked power wire to distributor during engine reving and i am getting 13-14 volts.

Ran a wire from the battery to the distributor and bingo and car started when cranking but obviously didnt shut off due to 12volt constant power. There are 2 small connections on the starter one is being used. Where does that go to? I wonder if the other one will give me a constant "acc" on power.
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Old 11-28-2003, 06:30 PM
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40 Thousandths is okay on the plugs, I prefer 45 with electronic ignition on the earlier engines.

The wire already going to your solenoid is the 12 volt start wire from the ignition switch that energizes the solenoid when you start the car. The other small terminal is the one that Jmark mentioned. All you have to do is run a wire from this empty terminal to the hot lead on your distributor. When the solenoid activates, it also activates 12 volts to this terminal as long as the engine is cranking over. It also stops sending voltage when you stop running the starter, so this will work fine.

I would be afraid that an ebay distributor would be the same or worse shape as the one you have now. Hold off on getting another one until you check out a few more things. The only thing a distributor really has to do is to deliver spark to the plugs at the correct time, and it sounds like it's working okay. I would expect backfiring or possibly loss of power if it were the distributor, but vibration is probably drive line problems. Check your universal joints. These can cause vibration under load sometimes and then settle down when not under power.
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Old 11-28-2003, 07:02 PM
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Should i run a different plug than the stock AC DELCO R45S plug or should i upgrade to a splitfire or at least a platinum plug? Also i just uped my gap to 45 thousands and cleaned them well. I will see when it stops raining if this helps at all. And thanks for the info on the starter wire. I was just looking at it and with the headers in place i will prob have to drop the starter first then run a 10 gauge wire ( 10 gauge right) to the distributor...

Last edited by pontiac69; 11-29-2003 at 07:25 AM.
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Old 11-28-2003, 08:57 PM
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You can get by with a 12 gauge wire for the starting circuit to the distributor. I believe that it is at high RPM's that the HEI's current requirements increase to a point that the 10 guage is extra insurance.

Your AC 45S plugs are a good choice, and you probably won't see any improvement with any exotic plugs. Splitfires don't cause any harm, but I haven't seen them improve anything in real life. I'd save my money. Platnium plugs on the next plug change might give you a little more life out of the plugs, but they probably won't help performance.
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Old 11-30-2003, 10:40 AM
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I just went through my hole fuse box. The ones that are acc on when cranking also lose power during cranking over the engine and get full 12 volts when i let go of the key for the car to run. Any thoughts.
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Old 11-30-2003, 11:11 PM
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You can either run the wire from the empty terminal on you solenoid like scholman and jmark suggested, or come off the ignition switch terminal 2 like I suggested. As you discovered, the accessory circuit won't work.
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Old 11-30-2003, 11:26 PM
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I don't know the hei stuff but I do know the plugs. I wouldn't run split fires I tried those in my firebird and right off they did help. but after about 2000 miles if you drive like i do (hard) they crap out. I prfer to run platnums I've had the best of luck with them for performance and reliability.
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Old 12-01-2003, 02:06 AM
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I admire the marketing skills of Splitfire. Think of the money they will have made after selling all of us one set. I don't think I have found anyone that has purchased a second set of them. My experience was at the drags. I ran my normal AC's, and then switched to the Splitfires. The next runs were exactly the same in time and MPH. No better - no worse. They are not a bad plug, but they seem to offer absolutely no improvement for the high price they cost. I suspect that people that notice an improvement with them had worn out plugs, and would have seen the same improvement with any new plugs installed.
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Old 12-01-2003, 08:35 PM
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30 years ago people made their own splitfires with a pair of side cutters. Marketing geniuses for sure.
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