Pro Flo 4 on a 347 SBF

[Robk]

I'm building a MK4 with a Blueprint 347 SBF and the Edlebrock Pro Flo 4 fuel injection. All purchased from Forte's Parts Connection. The Pro Flo 4 has a a serious mess of wires, so I'm trying to make it look as neat as possible. If anyone has pics of their installation, I'd love to see them. I'm trying to hides as much of the harness behind the firewall under the dash. What I think I'd like to do is mount the ECU on the inside of the firewall and run the wiring harness through the firewall directly behind the center of the engine - rather than snaking the harness through that access hole on the passenger side of the firewall. That poses two problems. First, the harness connections are so big it will have to be a big hole. I guess I could go with a split firewall grommet. Second is with the distributer on the front of the engine, the harness really isn't quite long enough. Any idea if there is an extension available for it? Your thoughts and comments are appreciated.

[JMD]

Check out Gbranham's build thread. He's running a 427 with that same EFI.

Also this thread should probably be moved from the build thread page to the general roadster forum page.

[gbranham]

I didn't have any wire length issues on my 427 with ProFlo4. There is definitely a lot of wiring, and I snaked it through the passenger side of the firewall and mounted the electronic bits on the inside of the firewall. My build thread has a lot of pics of this, starting around post #169. I will say...you don't see much of that wiring once the body is on. Even the wiring in the engine bay against the firewall is pretty well hidden, because it's sitting on the top of the bellhousing (ish), and the air cleaner obscures the view. And you don't see any of it when the hood is closed and you're driving the car.

Greg

[Robk]

Thanks. I looked at the pics in your build thread of the wiring on the firewall. It does look pretty good. If I run the coil and distributer harness straight back to the firewall along the left cylinder head like it appears you did, the harness is barely long enough to reach through the access hole above the passenger footwell. And, there's about 10" too much of the injector harness. Frankly, it seems like the harness if for an engine with a rear distributer, like a SBC.

[narly1]

Consider switching out the intake manifold bolts for longer studs. That way you can use 2nd nuts and P-clamps as anchor points to tidy up the injector wires a bit.

Earl

[gbranham]

Thanks. I looked at the pics in your build thread of the wiring on the firewall. It does look pretty good. If I run the coil and distributer harness straight back to the firewall along the left cylinder head like it appears you did, the harness is barely long enough to reach through the access hole above the passenger footwell. And, there's about 10" too much of the injector harness. Frankly, it seems like the harness if for an engine with a rear distributer, like a SBC.

Yeah, I didn't encounter any of that. You sure the injector harness isn't swapped left to right? I almost made that mistake. The injector plugs on the harness are labeled for each injector. Look at #1 (passenger side front) and see if it's labeled '#1'.

Also, I seem to recall there was a short (8"-ish) wiring extension that connected the distributor to the actual harness, to give a bit extra length.

Here's a screenshot from the instructions. Note #10...

Screenshot 2025-06-26 164121.jpg

Greg

[Robk]

Ahhh.... I didn't see that in the instructions. That's what's missing! However, a quick internet search shows that part number discontinued. I'll try to contact Edelbrock.

[gbranham]

Ahhh.... I didn't see that in the instructions. That's what's missing! However, a quick internet search shows that part number discontinued. I'll try to contact Edelbrock.

If they don't have the part, it's not the end of the world. It's just two wires. They're easily extended.

Greg

[Robk]

That was the problem. Edlebrock is sending me the harness extension. Any chance you know the part numbers of your radiator cap assembly with the upper radiator hoses? My engine is like yours with the upper hose connection pointing straight up. What FF included in the kit is a straight hose, which I'm guessing is for a Coyote motor or something.

[gbranham]

I bought Breeze's upper and lower radiator hose bits, which came with the T-Filler. I ended up swapped to a 10lb cap, and used a Gates #21211 hose for the upper hose, cut, of course, to accommodate the t-filler.