Hey guys,

My winter project is going to be replacing my Holley 750 VS carb with EFI. I've been researching and I think I've settled on the Holley Commander 950 TBI system, but I'm looking for some confirmation before I order. It's going on a ZZ4 with GM's Hot Cam kit and a 420+ HP dyno slip. It is mainly just street driven, only raced when I find Click at a stoplight in town and his trigger foot gets itchy. i realize I'm missing out on some performance by not going multi-point, but I can't convince myself to spend an extra $800 for that system. I want clean, easy starts and the constant performance of EFI.

So, any users out there that can say "good choice - you'll love it"?

Any other opinions of something I'm overlooking?

Jeff, I used that tbi on a moderate 350 in a truck around 10 years ago, and liked it a lot. Fast easy starts in any weather, good performance, excellent tuneability. The commander 950 controller is the same setup they provide with the more expensive multi-port system, it was a ball driving around watching the sensor display on the laptop!

The system is 100% complete except for fuel lines, and is an easy weekend install. You will need a return line for the fuel, and that line must be the same size as the supply line, don't try to get away with using the 5/16" vapor line (if your car has one) it won't work, can't dump enough fuel at idle.

The only trouble I had with it was the supplied Bosch external fuel pump (I understand they have a better pump now) After it failed the third time, I used a conventional Holley RED pump instead. That worked great and had no trouble supplying the 14 psi the tbi needs.

I wouldn't hesitate to buy another. My efi upgrade is scheduled for next winter, and just may be a commander 950 tbi unless my budget eases some.

Although I have never heard complaints on the Holley system, you may want to check out this and others. http://www.customefis.com/tbiused.html I'm not sure if he could make a system with your HP rating or not .

thanks jim! I am wondering how to plumb the return line into the tank. any suggestions?

I've been "starting the setup" on my 68 for years.
When I got the car, it needed a new sender, so before I installed it, I drilled a hole, and brazed in the inlet tube from my old sender (cut short so it only sticks in a couple inches) This will be my return.

I'm now replacing all the hard lines under the car. I'll order 2 complete fuel lines, and rebend the second as required so I can run them side by side. I'll use the original hold downs if I can (they were made to hold 1 3/8 and 1 5/16, so we'll see) or just use a different type of clamp in the stock location.

The vent line will attach at the rear, where the original feed line attached and hook right up.
I'll rebend the new feed line to end a few inches sooner, and buy a second original type bracket to hold it.

The external pump and both filters will mount to a sheet of alluminum, which will hang down from the floor where the transverse muffler used to go, plenty of room for it there. The pump will mount as low as possible, with the filters above it.

I'll run a 12 gauge wire along the existing body harness to the pump, and out thru the speedo cable grommet to the Holley relay. I will incorporate an oil pressure fuel shut off, something holley did not include back then.

I'm running this system on my 69 with a 454/TKO-600 Lunati Bracket II cam. So far so good, I still needs some fine tuning above 5500rpm. Definately idles and handles cold starts better than it did with a carb. The one piece of advice I would highly recommend is getting a computer controlled distributer. The only real problem I had at start up was getting it to idle under 1400rpm. I got a dist out of a 91 Impala turned it down on a lathe to fit an old style intake. It was night and day on how it idled. This allows the Commander to adjust idle with timing and the idle control valve. Since timing can be adjusted instantly it will pull timing as it races or add as it starts to die. In layman's terms the Idle control motor acts as a rough adjustment and the timing fine tunes it. I'm running the 75 lb injectors and maxing them out at 6000rpm. Depending on your MAX rpm you may want to concider the 85lb injectors.


I started with a Tunnel ram and Dual 660's, a few years later I switched to an 850, then the Commander TBI. Each change brought better driveablity but less power (big jump from the tunnel to the 850).

I really must be getting old I've had the car for 20+ years and the first 15 were all about getting it faster now I'm slowing it down as I focus on driveablity. Its hard to beat a Fuel Injected 69 with a 5 speed though.