Nice work. I’ll be interested to hear the reports of how it works once you get it all together.

That is way cool, you always epitomize the built not bought mentality

How much HP do you think those injectors and the new larger airflow bore can support? I know you're not going for crazy high #'s, but I am just curious.

I am totally blown away by this. I have little knowledge of what it takes to make this work. I will follow along and learn.

rpm wrote:

Damn nice work Daze! Do you have any pics of the work piece in the lathe. I'm interested in how you chucked it up.

Thanks!!  

I didn't take any pictures when I modified the unit but it only took me a minute to pull it apart and chuck it up in the lathe to show you how I did it.

Like I said above the bore at the butterflies was 1.56" but then there was a lip (not even a smooth transition) where it went down to the smaller size.  Not sure why Ford did that there were two versions of this CFI and one was necked down and the other wasn't.

In this picture you can see a distinct line where the original darker bore meets my enlarged bore.


To do the machine work I simply used a reverse hold on the butterfly part of the bore and then an internal cutting tool (boring bar) to enlarge things. 

Raymond_B wrote:

How much HP do you think those injectors and the new larger airflow bore can support? I know you're not going for crazy high #'s, but I am just curious.

Its going on a 351W The rule of thumb with injectors is you want the sum total of Lbs/Hr to be 1/2 of max horse power assuming you will not be running it at max most of the time.  The extra injectors are 46 each (not the ones in the picture those are sacrificial 18s) and the two injectors actually mounting in the unit are 52 each for a total of 196.  That means I am good to a max HP of 392.  According to my desktop dyno (which tends to be a little high) this engine should produce at most 371 HP at 6000 RPMs so I am good for fuel.  As to air flow the new enlarged bore is the same as most 2 barrel carburetors at the butterflies but carburetors neck down with a custom shape to create the venturi effect so it should flow better than a stock 2-barrel.  I know engines as big a 390s have gotten OEM 2-barrel carbs and run well so I think my airflow will be sufficient.  I know I won't be maximizing HP but I probably won't spend much time running it above 4500 RPM so it shouldn't be and issue and the 2-barrel setup should be good for low end torque with is the goal of this build anyway.
 

MS wrote:

A shop down the street is using a GM TBI setup with good success on lots of different engines.

My son has 1994 Chevy 2500 4x4 with the GM TBI with 260K on it and it still runs Great!
 

Looking good Day! Leave it to you to come up with something like this. Keep us posted on the final build and run test results.

I really hope it works out just fine, Day.  I look at projects like this as "educational".  Like my sealed cowl with air intake up front....not so good.  Or, my home brew HVAC system that included fresh air intake as well as recirculate.  That worked pretty well but needed more blower and a little re-engineering.  It was such a PIA to R&R for experimentation that I just went to the Gen IV.

BB

 

Question from an Old skool carb  kinda guy...... When you milled out the bore you said you  'tapered the top a 1/2"'. What would happen if you tapered it further on down the bore?! Why just 1/2" down?
Pretty cool  stuff Daze!
6sally6

Daze wrote:

Fantastic question!!

If I had taken the taper down close to the butterflies I am sure I would have picked up a little more flow, but to be honest I was trying to do the minimum amount of machining.  It was very stressful having that large unbalanced mass spinning around on the lathe.  Also I hit some small air pockets in the process of boring it out so I didn't want to press my luck.  Basically I was white knuckled the entire time I was doing it and hit a point where I said "good enough"

 

I/we all can relate!! Holding your breathe for long periods of time just CAN'T be good for you!!
6s6

jkordzi wrote:

Hey Day.  Very interesting.  I looked at Megasquirt many years ago when everything was open and free but never pursued it.  Do you have an idea what your system will flow in cfm?

This unit is basically modeled after a Motercraft 2-barrel carb and I believe the 2-barrel carb had a CFM somewhere in the neighborhood of 500 CFM.  I know thats a little small for a 351W but Ford put 2-barrel carbs on bigger engines like 390s also with the overdrive on the T5 and ram air I think I will be ok.  I also know the smaller flow should give me better low end torque and thats what I am after being that its going in the Galaxie.