Im looking for the best way to run a 4 barrel holley 950 tbi. I know I can use a 730, 749 or even my stock 305 tbi computer If i build a injector driver for the additional two drivers. My only concern is at low throttle and idle. The tbi has a progressive throttle linkage so two injectors would spray against closed butterflys. Holleys commander ecm turns off the back two injectors until the rear butterflys start to open. Does anybody know how to build a switch to turn on the injector driver using a tps signal? Should I not worry about it and make the tbi a 1-1 linkage so all butterflys open at once?
Any info would be great
Thanks

 

1:1 is def. an easier option. and i would think just as good as one.

i have progresive linkages on my Audi, and it kind of bothers me.

 

Curious, What bothers you exactly?

 

soft pedal, nothing, soft pedal, nothing, hard pedal, then it goes.


i guess what really bothers me, is you really have to nail the throttle on heal-toe shifts to get the revs to spike. it might be all in my personal preference, or how audi handled the progresive system, but i prefer a good linier fell to everthing.

 

I plan on using a 740cfm Holley 4bbl TBI that I got from Howell Eletrictrontics with the 8746 ECM & no extra driver board. Howell insits it works fine with just a chip reprogram. Everyone here keeps telling me it won't work, but I guess we'll see in a couple or three months when my 388ci gets balanced and stuck together. I just wonder what you need to feed fuel to a mid500's Hp & high 600's TQ, will the 740cfm 4bbl even do it?

 

You might want to bump up to the same tbi size that I am using. Do you know how howell deals with the problem of progressive linkages? I was looking at my tbi tonight and it will be hard to convert to 1-1 throttle because the butterflys turn in opposite directions.

 

Is this the TB you have? That looks they open the same way...

http://www.holley.com/HiOctn/ProdLin...f9900-171.html

 

I checked out the link. The TBI that I have does not have the same link as the one in the pic. I tried to find a picture like the linkage that i have on holley but I could not find a close up.

 

If you are good, you can make something.

If the linkage that connects the two is anything like the one on the TB I showed, you just have to fill that slot with something, or make a similar type of piece (without the slot) to replace it.

If worse comes to worse, you can make your own linkage by locating a linkage rod on the TB. When looking at it from the side, attach the rod to the front at 3 o'clock, and the back at 12 o'clock. That way when the front throttle is opened, it will pull the back throttle an equal amount to the front, but in the opposite direction.

If you were to do that, the distance where the rod attaches to each throttle would have to be the exactly the same from the center of the throttle shaft on both. That way they're opened exactly the same amount at the same time, and will both be fully open when you're at WOT.

If the it's connected farther away from the centerline on the back throttle, it will not open completely. If it's closer to the centerline the back throttle will open to WOT befor the front does.

Here's a (cartoon) pic to better explain.

 

I figured it out. There is a smaller hole on the primary side linkage. The Rod would not fit in the hole and was not long enough to connect both linkages. I made a test rod out of a piece on hanger and connected the two linkages. It works! I think holley probably has a rod built just for 1-1 applications. If not it will not be hard to make one. The holes are already there.

I can only see a couple more small problems that should be easy to fix. THe throttle linkage is on the bottom half of the tbi. It would have to be pulled from the front of the car to open the blades. I tried taking off the butterflys and pulling out the primary shaft. I thought I could pull the linkage bracket off and flip it 180 degrees. Turns out it wont work. It looks like it was put on from the end and then the rod was flared to hold the bracket. I will just have to cut off the bottom half and weld it to the top.

The finnal problem I can see is the PW at low throttle and Idle. I dont see any way of shutting off two injectors without holley ecm. At least If It works the fuel will not be spraying on the back of the butterflys due to a progressive linkage setup