L29 454 swap

Status
Not open for further replies.
Down to the punch list.
Shes roadworthy!!!!

first trip on the highway today. Pre-swap 350/th350 65mph was 4000 rpms. Post swap, 75 mph is 2500 rpms.
She runs super smooth. I have to re-run a brake line going into the proportioning valve because it runs directly through the direct path of the exhaust. thats being done on Friday. Then Monday it goes to the exhaust shop to have some pipes put on it. My neighbors are already aggravated with the open header big block.

Then its just going to be a matter of zip tying everything to safe places, and running some new loom and heat shrink over the wires.

OMG the Torque. The first 2 gears are useless at anything over half throttle, especially with a 3.73 peg leg, but boy do I love this thing!
 

Attachments

  • A265B243-9FEA-4AF5-AF2F-B54CA84C280D.jpeg
    A265B243-9FEA-4AF5-AF2F-B54CA84C280D.jpeg
    1.5 MB · Views: 173
New update, and request for help. The car is down with a charging system issue, i got stranded about 35 miles from the house. Meh, Project car life.

As you know, this is a complete 2000 C2500 Vortech 7.4 4L80E swap with all of the factory EFI components. I utilized a Howell EFI harness ($$$$$) and a Howell tuned computer.

When I had the car apart, I took the opportunity to upgrade alot of the Charging system wiring. The Big 3 upgrade was performed, so the ground straps are heroic everywhere. Firewall to Block, Block to Frame, Body to Frame, Battery ground to block and chassis.

The Battery is a 3 month old Duralast. The Alternator was the stock one that came with the truck, it had a date code that looked like it was only 3 years old, so we kept it. It is a CS144 140 amp alternator with the rectangular 4 prong plug, and then its a 1-wire alt, so there is just the single Power wire going to the battery.

The alternator plug that comes on the Howell supplied harness only has 1 wire attached to the 4 prong plug (which I have seen before), and the plug itself is 1 large prong, with 3 equal smaller prongs in a row next to the large prong. The plug supplied by howell has the single wire going to the smaller prong immediately closest to the large prong.

The stock C2500 truck positive cable to the alternator and starter was deemed to be beefy enough, so we kept it.
I guess for the last couple of days the car had been running only off the battery, so it eventually discharged completely to the point where the ignition cut out while I was driving on I-95 yesterday.

The car will run off the battery after the battery is charged. The car will run off of a jump as long as the cables are connected. The car will run off of a battery charger (poorly) as long as it is connected.

The car will not run if the battery cables are disconnected after the car has already started. Removing the battery cable results in the car dying.
The Alternator was replaced with a brand new car quest CS144 140 amp alternator yesterday. Same symptoms persisted with the brand new alternator.
Ground continuity tests perfectly. When the charge on the battery is up, the battery tests 12 volts across the terminals. When the car is running off the battery with no charger, it tests 12 volts between the terminals, although it is naturally decreasing as the battery discharges.

The Brand new alternator was disconnected from the Battery, the battery was juiced up enough to test the alternator. Alternator is putting out 0 volts and 0 amps at the charging stud.

What am I missing?
 
Your single wire on the Howell harness is hooked to the wrong 1 of 4. 3 more to try!

See if you can find out which is the "excite" wire for the alternator. Also, verify that the wire in the aftermarket harness has 12v in run position. When the alternator is properly "excited" (oh my!), it should be putting out 13.8-14.4 around 3000 rpm.
 
Down to the punch list.
Shes roadworthy!!!!

first trip on the highway today. Pre-swap 350/th350 65mph was 4000 rpms. Post swap, 75 mph is 2500 rpms.
She runs super smooth. I have to re-run a brake line going into the proportioning valve because it runs directly through the direct path of the exhaust. thats being done on Friday. Then Monday it goes to the exhaust shop to have some pipes put on it. My neighbors are already aggravated with the open header big block.

Then its just going to be a matter of zip tying everything to safe places, and running some new loom and heat shrink over the wires.

OMG the Torque. The first 2 gears are useless at anything over half throttle, especially with a 3.73 peg leg, but boy do I love this thing!

Looks like a street sleeper to me !!
I've shown many a Mustang around here the tail lights on my Monte.
They just got no idea when they see an old feller like me in an old car,LOL
Guy
 
What exactly is your computer situation? 98+ had more than 1 wire in the alternator, I want to say it was the F terminal but don't quote me. That terminal tells the alternator how much to out out based on what the PCM commands. If it's not there, the easiest thing is to get a 96-97 Vortec alternator. If the computer is set up for it, you'll want to get the correct pigtail. Is it a reflashed 2000 PCM? 96-97 were different. On a 411, you can check a box that says whether or not your alternator has that pin. Try pulling codes and see what comes up after a short non-battery killing drive. I'm not sure if this would totally prevent it from charging, but it is something that needs to be right.
 
Its a 99/2000. The computer is a 2000. I called howell and they said i could just jumper it to the power wire, and that would excite the alternator, abd the exm wouldnt care. I think the issue is its not playing well with the stock Monte alternator idiot light, which the instructions called for it to be hooked up to. I have a volt gauge anyway now, so the idiot light is superfluous. I’m going to try jumping it per Howell’s instructions and see if i can get some power out of the alternator.
 
Its a 99/2000. The computer is a 2000. I called howell and they said i could just jumper it to the power wire, and that would excite the alternator, abd the exm wouldnt care. I think the issue is its not playing well with the stock Monte alternator idiot light, which the instructions called for it to be hooked up to. I have a volt gauge anyway now, so the idiot light is superfluous. I’m going to try jumping it per Howell’s instructions and see if i can get some power out of the alternator.

That's incredibly half-assed on their part. I'm not sure that you can disable alternator control within a 2000 PCM. They left a wire out of the engine harness and told you to jumper the damned thing instead of doing it right or offering you a corrected harness.
 
Your single wire on the Howell harness is hooked to the wrong 1 of 4. 3 more to try!

See if you can find out which is the "excite" wire for the alternator. Also, verify that the wire in the aftermarket harness has 12v in run position. When the alternator is properly "excited" (oh my!), it should be putting out 13.8-14.4 around 3000 rpm.
That's incredibly half-assed on their part. I'm not sure that you can disable alternator control within a 2000 PCM. They left a wire out of the engine harness and told you to jumper the damned thing instead of doing it right or offering you a corrected harness.
^^This ^^
Sounds like the wiring from the alt to the elect system should be the focus.
 
Status
Not open for further replies.

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact [email protected] for info on becoming a sponsor