Is there anything fundamentally wrong with this part? It's an adapter plate between my throttle body and my stock 12a manifold. I'm about to start converting it to G codes and I want to make sure its all straight first. The throttle body is 2.25". 4 MSD injectors. It's aprox. 3 inches tall.

 

Where it splits into four, you want rounded, not sharp, edges.

If possible, make it so it's basically a small plenum, and the four ports are bellmouthed like the end of a saxophone.

 

Well I have some background in turning the 12 to FI and I would say it really needs to be redesigned to acomadate 2 throttle bodies not 1.

You will want the bigger of the 4 ports to connect together to a larger throttle body with larger injecters and the smaller ports to connect to a smaller throttle body with smaller injectors.

Then it would just be a matter of controling the additional 2 injectors in stages and fabbing up a pretty crazy throttle linkage system.

If your wondering why a 86+ 13b has only 1 throttle body it is because inside the throttle body there are three ports, 2 same size 1 larger. 2 of the fuel injectors are located directly on the housings spraying inside the motor.
The other 2 are on the middle manifold on their own ports.
After the throttle body you have the dynamic chamber which controls air flow to the 4 ports and of course divides the 1 port into 4.


Basically you would need either the same system as above or 2 throttle bodies dividing the 4 ports into 2 sets of 2 ports each set with independant fuel/air flow on each set to get maximum performance, drivability, and of course decent gas milage.


Thank of your current 4 barrel carb, now think of it with all 4 jets still spraying fuel in their 4 corners but now they are all the same size and instead of 4 butterflies you now have 1 huge one controling air/fuel flow.

The throttle body adapter you have the diagram of would work, but how well or poor is another question.

 

So It's gonna be TBI with the Throttle above the injectors?

 

to above yes. This is just my first one to see if i can get my own fi system running on my 12a motor. This winter I hope to be building a 13b and then i'd have a differnt manifold to adapt to. I will use a much larger throttle body on the new one, or I'm considering making my own throttle body with injectors, with 4 seperate butterflys. On the 13b's lower manifold isn't it 4 round ports pointing vertical? Id' probably mount a butterfly and injector on each of those, to horns inside of a plenum, like suggested. Then I'll be running boost.

On this design I'm going to figure out how im going to get smooth lines instead of sharp lines like suggested.

I never knew the ports were operated seperately. Can someone explain this?

 

Also if you made the spacer longer, the transition would be better.