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Discussion Starter · #1 ·
If you are handy with tools, it's relatively easy to convert from progressive throttle linkage to 1:1 throttle linkage on the early design Edelbrock 4150 throttle body that comes with the Pro Flo 4 kits. The same concepts could be applied with the newer design throttle body.

Before I started fooling with this, I tried to buy the 1:1 linkage parts from Edelbrock, but it was a dead end. Edelbrock support told me they don't make a kit to convert from progressive to 1:1 for their MPFI 4150 throttle bodies. They use to provide the parts (not a kit with a part number) for making the conversion with some of the pricier 4500 throttle bodies, but since changing the throttle body design across the entire line, those parts apparently got pulled. I don't really know. All I do know is I couldn't buy the parts.

Moving right along... To make it all work I fabricated a new linkage bracket and replaced the linkage bracket that operates the secondary throttles and is attached onto the primary throttle shaft, and replaced the link between the primary and secondary throttles. That's it.

My prototype bracket I made is on the left, and the progressive bracket from the older Pro Flo 4 4150 throttle body is on the right. The lower hole in the bracket I made supports 1:1 operation. The higher hole is progressive.


My bracket is larger than it needs to be for 1:1 operation, but I wanted to support progressive linkage with the same part for grins. The upper hole for the link would make the secondary throttles come in around 45-50%. That is a guess though, since I haven't actually tried the link in that position. I did try it on another bracket I made with a hole about halfway between the two positions shown, and the secondary throttles started opening around 15-20%.

I started with some 1/8th-inch x 1.5-inch aluminum flat stock for the bracket. I guessed at the geometry and measurements for the bracket by looking at the 1:1 throttle linkage on my FiTech Go Port throttle body. I also used some imagination. I used the adjustable link off the FiTech throttle

Prototype on the throttle body.


Tuning changes are minimal with Pro Flo 4 EFI. A little more accel pump fuel is all it takes to support all 4 throttles opening at once.
 
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Nice!!!! I have been eyeballing my Proflo 4 throttle body for about three weeks now dreaming of what it was going to take to get that bugga to 1:1. You have a nice piece there. Also interested in buying one from you or a template. Good work there :grin2:
 

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Discussion Starter · #4 ·
any chance on making a few more and selling to us?
I couldn't make affordable ones without having them made in the thousands. Making the part the way I did is time consuming and barbaric. Besides, the adjustable secondary rod link I used has proven impossible to source in the correct length so far. The adjustable rod is expensive too. Holley charges $35 for one that is the same design, but too short.
 

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I know this is an older Post but I was hoping you would tell us what was the outcome of going 1:1 on the Pro Flo 4 linkage ?
Did the car car perform any better at initial throttle ?

Any chance you could provide a template for the the flat bracket portion of the linkage?

thanks
 

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Man thats slick !
 
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