1968 Impala Repower Thread - Page 4 - Impala Tech
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post #76 of 111 (permalink) Old 07-27-2019, 05:31 PM
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I have no idea what "this" is. Photo is out of focus and too small to identify terminal.

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post #77 of 111 (permalink) Old 07-27-2019, 05:50 PM Thread Starter
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Sorry about that. Try this one... Thanks.
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1968 Impala SS
496 Stroker
T56 Conversion
3.73 Posi-Trac
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post #78 of 111 (permalink) Old 07-27-2019, 07:21 PM
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That is the auxiliary IGNition terminal that is hot only when the key is on. You use it for an electric fuel pump or other itm you do not want running when the engine isn't.

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post #79 of 111 (permalink) Old 07-28-2019, 08:57 AM Thread Starter
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Dave, I get zero volts at IGN at both the "Run" position and when cranking. Replaced the fuse with no luck. The IGN source at the ignition switch drops from 12V to 10V when cranking, so that's no good either. I ran a 10 GA circuit directly to the starter and it didn't help the voltage drop at all.

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post #80 of 111 (permalink) Old 07-28-2019, 09:31 AM
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Originally Posted by 68WASAGOODYEAR View Post
Dave, I get zero volts at IGN at both the "Run" position and when cranking. Replaced the fuse with no luck. The IGN source at the ignition switch drops from 12V to 10V when cranking, so that's no good either. I ran a 10 GA circuit directly to the starter and it didn't help the voltage drop at all.
Do you have the wiring diagram for you car? That shouldn't be a hard circuit to chase down.
I have a couple of different OE documents here in Greenville that should help you out if you need it.

1969 Imapala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #81 of 111 (permalink) Old 07-28-2019, 10:11 AM
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Voltage dropping when cranking is normal. Ignition runs on 8 volts as their is a resistor in the wiring to drop the voltage. The purple wire from the starter to the coil provides a full 12 volts to the ignition when cranking to compensate for the voltage drop in the system while the battery is discharging at a rate of 200 Amps/hr.

In order to measure the voltage at the IGN terminal you need a ground. What are you using? I use a 25 foot roll of ten gauge wire with an alligator clamp on the battery terminal and what ever I need on the other end to test with.

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post #82 of 111 (permalink) Old 07-28-2019, 06:31 PM Thread Starter
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Quote:
Originally Posted by 68WASAGOODYEAR View Post
Dave, I get zero volts at IGN at both the "Run" position and when cranking. Replaced the fuse with no luck. The IGN source at the ignition switch drops from 12V to 10V when cranking, so that's no good either. I ran a 10 GA circuit directly to the starter and it didn't help the voltage drop at all.
Do you have the wiring diagram for you car? That shouldn't be a hard circuit to chase down.
I have a couple of different OE documents here in Greenville that should help you out if you need it.
I do, but I need two seperate, clean 12V sources at the run position and during cranking for the EFI and holley dual sync distributor, so the factory diagram isn't much help. I have one on the back of the ignition switch, but the problem is the voltage drop. I think I need a relay or two to get around this issue. Will talk to an electrical engineer tomorrow at work to confirm.

1968 Impala SS
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T56 Conversion
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post #83 of 111 (permalink) Old 07-28-2019, 07:46 PM
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Your car ran off of the battery and used the alternator to charge the battery back up after use. This leads to large swings in the voltage. Because of this Chevy introduced the CS style alternator (what the aftermarket calls a one wire) to run the cars computers.

Transistors are very, very susceptible to variations in voltage. It doesn't take much to go from static and misfires to dead parts with your current battery and SI alternator. You could fill the trunk of your car with the battery out of an electric fork lift truck and that would maintain stable voltage while the alter maintained charge. But you would be dragging the frame due to the added lead weight.

Or swap out your SI alternator for a big (105 Amp or bigger) to run your computer and the rest of the car. The CS outputs it's rate Amperage and maintains it at 12 volts from 2,400 RPM and up. Your SI isn't hitting rated power output until 4,600 RPM where the voltage is close to 14.6 volts.

It is just another reason I have never embraced EFI in a classic car.

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post #84 of 111 (permalink) Old 07-28-2019, 08:09 PM Thread Starter
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Quote:
Originally Posted by Big Dave View Post
Your car ran off of the battery and used the alternator to charge the battery back up after use. This leads to large swings in the voltage. Because of this Chevy introduced the CS style alternator (what the aftermarket calls a one wire) to run the cars computers.

Transistors are very, very susceptible to variations in voltage. It doesn't take much to go from static and misfires to dead parts with your current battery and SI alternator. You could fill the trunk of your car with the battery out of an electric fork lift truck and that would maintain stable voltage while the alter maintained charge. But you would be dragging the frame due to the added lead weight.

Or swap out your SI alternator for a big (105 Amp or bigger) to run your computer and the rest of the car. The CS outputs it's rate Amperage and maintains it at 12 volts from 2,400 RPM and up. Your SI isn't hitting rated power output until 4,600 RPM where the voltage is close to 14.6 volts.

It is just another reason I have never embraced EFI in a classic car.

Big Dave
Dave, I switched to a CS alternator early on when I first bought the car. Would the alternator have anything to do with this when cranking? I tried running a 2 GA wire between the alternator and battery just for the hell of it and it didn't make a difference in terms of the voltage drop.

1968 Impala SS
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post #85 of 111 (permalink) Old 07-28-2019, 10:03 PM
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One wire means you get no charging from the alternator until it "lights off" at about 2200 RPM. You are relying on the magnetism of the iron core (not permanently magnetized but it retains some residual magnetic flux from running). If you want instant on you need to connect the field windings (there are pig tails that connect your blue and white wire to a CS alternator).

Otherwise you are back to cranking off the battery and hoping you have enough charge to keep your voltage up.

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post #86 of 111 (permalink) Old 07-29-2019, 10:53 AM
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Originally Posted by 68WASAGOODYEAR View Post
I do, but I need two seperate, clean 12V sources at the run position and during cranking for the EFI and holley dual sync distributor, so the factory diagram isn't much help. I have one on the back of the ignition switch, but the problem is the voltage drop. I think I need a relay or two to get around this issue. Will talk to an electrical engineer tomorrow at work to confirm.
Probably you do need relays...
What I can tell you about vehicle system voltage during cranking...(We make fuel injectors here in Greenville). For OE injectors, we manufacture to a SMOV of 6.5 volts. Static Minimum Opening Voltage is the lowest voltage at which a fuel injector will open and function. We design this way because it is not uncommon for system voltage on cranking to drop to as little as 8 volts. We see this though about the mid 2000's. With later ECUs, some cars don't even bother to send a signal to the starter below 8 volts. I think getting a dedicated circuit should be no issue but you'll never get a solid 12v during crank. The system just isn't designed that way.

1969 Imapala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #87 of 111 (permalink) Old 07-29-2019, 11:55 AM
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I think getting a dedicated circuit should be no issue but you'll never get a solid 12v during crank. The system just isn't designed that way.
You can get 12 Volts while cranking you just need a bigger battery:

https://www.foreverpureplace.com/24-...24-85-25-b.htm

But in all seriousness there is a special 16 Volt battery that racers use to run EFI on a race car. Battery has dual circuitry so that it never gets below 12 volts. Does require a charger that plugs into 110V AC household circuit to keep it charged.

https://lifelinebatteries.com/produc...s/ll-161240tb/

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post #88 of 111 (permalink) Old 07-30-2019, 08:09 AM
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Quote:
Originally Posted by Big Dave View Post
You can get 12 Volts while cranking you just need a bigger battery:

https://www.foreverpureplace.com/24-...24-85-25-b.htm

But in all seriousness there is a special 16 Volt battery that racers use to run EFI on a race car. Battery has dual circuitry so that it never gets below 12 volts. Does require a charger that plugs into 110V AC household circuit to keep it charged.

https://lifelinebatteries.com/produc...s/ll-161240tb/

Big Dave
Seems simple enough...

I still can't believe Holley requires a minimum 12v during cranking. One of our engineers provides tech service to them, I see if he can get a definitive answer.

1969 Imapala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #89 of 111 (permalink) Old 07-30-2019, 10:23 AM Thread Starter
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Quote:
Originally Posted by justjohn View Post
Quote:
Originally Posted by Big Dave View Post
You can get 12 Volts while cranking you just need a bigger battery:

https://www.foreverpureplace.com/24-...24-85-25-b.htm

But in all seriousness there is a special 16 Volt battery that racers use to run EFI on a race car. Battery has dual circuitry so that it never gets below 12 volts. Does require a charger that plugs into 110V AC household circuit to keep it charged.

https://lifelinebatteries.com/produc...s/ll-161240tb/

Big Dave
Seems simple enough...

I still can't believe Holley requires a minimum 12v during cranking. One of our engineers provides tech service to them, I see if he can get a definitive answer.
I spoke with holley tech support on the phone yesterday evening about the voltage drop and the voltage requirements of the EFI. They said there will obviously be some voltage drop during cranking, but that the amount I'm seeing (approx. 12.5V down to around 10.5V during cranking) seems excessive and that I should be fine with 11.0V+ for the EFI during cranking.

They suggested checking all my grounds, so I'll start there I guess. I have been hyper-vigilant about grounds and I'm pretty confident in them; all new grounds and even the old ones I've run across were taken down to bare metal, a ring terminal with splice melt attached to the ground wire, bolted to the bare metal, and covered in liquid electrical tape to seal /insulate the ground. All new ground straps were added during the engine swap as well. These were missing before.

I don't think it's the starter either; it's a new Summit high-torque mini starter which shouldn't cause that big of a drop.

Thanks for all the replies. This is the last thing before I can fire it up so it is super - frustrating.

1968 Impala SS
496 Stroker
T56 Conversion
3.73 Posi-Trac

Last edited by 68WASAGOODYEAR; 07-30-2019 at 10:50 AM.
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post #90 of 111 (permalink) Old 07-30-2019, 11:52 AM
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Like I said earlier the original starter (direct drive permanent magnet starter) with the added windings found in a high torque starter will drop a 12 Volts battery down to 8 Volts. You are ahead of the game with a mini-gear drive starter that doesn't draw as much current.

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post #91 of 111 (permalink) Old 07-31-2019, 02:02 PM Thread Starter
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Good grief. Watch 30 seconds of this video starting at 7:55. The Holley guy doing the install sees the SAME EXACT voltage drop I'm seeing during cranking and doesn't bat an eye. The car fires right up. 12V needed during cranking my ***. All this running around and overthinking the issue. Oh well. Hopefully this helps someone avoid all the nonsense.

https://youtu.be/1mIhs4xahBY

1968 Impala SS
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T56 Conversion
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post #92 of 111 (permalink) Old 08-06-2019, 10:18 AM Thread Starter
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Wired it up as shown in the video and had no problems. She's running now. Hopefully will have video soon.

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post #93 of 111 (permalink) Old 08-06-2019, 01:30 PM
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Wired it up as shown in the video and had no problems. She's running now. Hopefully will have video soon.
Looking forward to seeing your impressions. This is a winter project for me.

1969 Imapala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #94 of 111 (permalink) Old 08-10-2019, 04:46 PM Thread Starter
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Drove it today around my neighborhood. Still have a few kinks to work out. Here they are:

1) Idle quality is terrible. Sounds like a Harley and the entire car shakes. Going to have to call Holley tech support on Monday.

2) Throttle is very stiff and unforgiving. I put increasing pressure on the peddle to no effect and then suddenly - BAM. Tire chirps. Will mention this to Holley.

3) Something sounds like it is repeatedly smacking the underside of the car on the driver side with a hammer. It's especially bad in a left turn. No idea. Will have to take the wheel off and have a look.

4) Oil pressure is staying around 60 psi. Very little movement of the needle. Again, no idea. The fuel pressure guage also says 0 psi, which can't be right for obvious reasons. Electrical Gremlins. Fun.

Nothing disastrous. No leaks either, which I'm very happy about. Any thoughts on the above are appreciated. Pics to come.

1968 Impala SS
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post #95 of 111 (permalink) Old 08-12-2019, 08:55 AM
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Originally Posted by 68WASAGOODYEAR View Post
Drove it today around my neighborhood. Still have a few kinks to work out. Here they are:

1) Idle quality is terrible. Sounds like a Harley and the entire car shakes. Going to have to call Holley tech support on Monday.

2) Throttle is very stiff and unforgiving. I put increasing pressure on the peddle to no effect and then suddenly - BAM. Tire chirps. Will mention this to Holley.

3) Something sounds like it is repeatedly smacking the underside of the car on the driver side with a hammer. It's especially bad in a left turn. No idea. Will have to take the wheel off and have a look.

4) Oil pressure is staying around 60 psi. Very little movement of the needle. Again, no idea. The fuel pressure guage also says 0 psi, which can't be right for obvious reasons. Electrical Gremlins. Fun.

Nothing disastrous. No leaks either, which I'm very happy about. Any thoughts on the above are appreciated. Pics to come.
This is a self-tuning system? Holley is probably going to tell you to drive it some more on the first call.

1969 Imapala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #96 of 111 (permalink) Old 08-12-2019, 03:38 PM Thread Starter
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Quote:
Originally Posted by 68WASAGOODYEAR View Post
Drove it today around my neighborhood. Still have a few kinks to work out. Here they are:

1) Idle quality is terrible. Sounds like a Harley and the entire car shakes. Going to have to call Holley tech support on Monday.

2) Throttle is very stiff and unforgiving. I put increasing pressure on the peddle to no effect and then suddenly - BAM. Tire chirps. Will mention this to Holley.

3) Something sounds like it is repeatedly smacking the underside of the car on the driver side with a hammer. It's especially bad in a left turn. No idea. Will have to take the wheel off and have a look.

4) Oil pressure is staying around 60 psi. Very little movement of the needle. Again, no idea. The fuel pressure guage also says 0 psi, which can't be right for obvious reasons. Electrical Gremlins. Fun.

Nothing disastrous. No leaks either, which I'm very happy about. Any thoughts on the above are appreciated. Pics to come.
This is a self-tuning system? Holley is probably going to tell you to drive it some more on the first call.
The rough idle is due in part to my O2 sensor placement: too close to the engine and needs to be further downstream. Will fix this at the exhaust shop. The stiff pedal is discussed here

https://forums.holley.com/showthread...I-WAAAY-Better

and there is a fix. I have ordered the linkage and will report back if it works. Apparently it's more or less required for manual transmissions.

The thumping sounds are an interference between the driveshaft and body. Crawling under there tonight...

1968 Impala SS
496 Stroker
T56 Conversion
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post #97 of 111 (permalink) Old 08-17-2019, 07:48 PM Thread Starter
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Any idea why my starter would make a grinding sound when starting the car? Only does this intermittently. Same sound as when you try to start it when it's already running. Whenever it does this, I key off and start over and it is fine...Thanks for any replies.

She's in the shop now getting new tires, exhaust, and a re-gear. Pics to follow and lessons learned. What a long, strange trip is been...

1968 Impala SS
496 Stroker
T56 Conversion
3.73 Posi-Trac
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post #98 of 111 (permalink) Old 08-21-2019, 04:04 PM Thread Starter
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Drove the car today and unfortunately ended up sitting in traffic, which I try to avoid at all costs.
The temp guage started to creep up and got to 225 before I was able to get moving. Once moving at a steady speed, it came down to 180 or so.

Do I need efans? Everything is brand new - water pump, the biggest, baddest cooling pack made by U.S. Radiator, mechanical fan, fresh coolant, etc. I'm not sure what else I could have done to avoid an overheating issue....

Thanks for any replies.

1968 Impala SS
496 Stroker
T56 Conversion
3.73 Posi-Trac
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post #99 of 111 (permalink) Old 08-22-2019, 12:04 PM
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I think the only difference between our power plants is fans. I have a Griffin radiator with their dual electric fans. With AC on, mine creeps up to 200 sitting in traffic.

1969 Imapala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #100 of 111 (permalink) Old 08-22-2019, 02:01 PM Thread Starter
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Quote:
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I think the only difference between our power plants is fans. I have a Griffin radiator with their dual electric fans. With AC on, mine creeps up to 200 sitting in traffic.
I'm going to add an electric 3000 cfm Flex-a-Lite auxiliary pusher fan on the front of the radiator and use the ECU to activate it above 200 degrees. This should do the trick. I don't want to convert over entirely to efans as the mechanical fan does just fine at speed.

1968 Impala SS
496 Stroker
T56 Conversion
3.73 Posi-Trac
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