Bought a GM part #17113186 which is a vacuum compensation fuel regulator for my TBI 383. It boost the pressure up to 20 psi and then the vacuum brings it down to 15 psi at idle. Car runs a little rough and has black smoke out the tail pipe. Running rich I would guess. Is that other 1.5 psi enough to cause this? Can the regulator be made adjustable?

 

That unit is adjustable. You have to break loose the torx screw in it and back it out a tad. Adjusting the pressure with the regulator is only really a stab in the dark. You really need to burn a new chip to get the proper fueling. The adjustable units just help you get things started. It is a crutch sorta.

 

be careful breaking the screw loose. i think it is loctite'd in or silver soldered or somethin. i dont think you can move the screw with a tork bit. anyway i could not. you may need to heat it with a torch. maybe someone can comment how to do it without stripping it. did not work for me but i got impatient and went to tuning with 90# injectors as it is a true bandaid solution..

 

Yea mine was in there tight. After I broke off the little tab I used a torx bit and applied a lot of downward force as i turned it. it did not want to go at first but I went really slow and it slowly moved. I exercised it a bunch and now it turns quite freely.

 

Running the Cop Car injectors from Turbo City along with their TBI and also their reprogramed chip. Scan tool showed me running a little lean so I thought I could richen it up a little with more fuel pressure. I think I over did it.

 

The tee fitting I installed in the MAP Sensor line was leaking. Ran new vacuume lines and tee fitting and all is well. Though still want to make the regulator adjustable.

 

It is adjustable. Just break off that tab and turn very slowly. You may need to introduce heat but I didn't have to.

 

You want to supply vac to the map with its own supply, not teed. It is very sensitive.

Break the tit from the center of the torx screw. Install the appropriate bit and apply a little heat with a propane torch and work the screw back and forth. I disassembled mine before heating so I wouldn't have to worry about damaging the diaphragm.

 

Ok, Back to the parts house for a little torx bit. Under the hood again to look for another source of manifold vacuume to run the regulator.

 

i placed a nipple on the brake vac line brass right angle manifold fitting.. purfect position...

 

Do you have an open element? I use the thermac port that was capped during that. Even if you still have the stock air cleaner assembly you could still use the thermac port.

 

This may help.

 

I am running a HO L69 Dual Snorkel Air Cleaner with no vac lines going to it. Where you show the thremac port is where my vacuum line goes to my charcoal canister. I guess the only other option is the EGR port if that is manifold vac, the thremac port is not.

 

Looked at your pic again, I only have the three ports on the front of my TBI not four like in your pic.

 

You should have 4 on the front and one in the back. The 305 and 350 TBI units are the same. Do you have a pic by chance?

 

I can get a pic in the morning. I bought the TBI from CFM Tech. It only has the three ports which is all I needed till now.

 

Do you know if that is a Rochester casting?

 

Noi I sure do not. I can get that in the AM also. How do a send a pic?

 

If you want to post a pic you have to attach it by using the "browse" box you see before you submit your post. Then just scroll to whereever the picture is on the computer and click select and when you post it will appear.

 

Rochester cast # is 17091058. There seems to be another port that has a plug in it. I ended up teeing off on the EGR valve. I tried to send a pic but it says the file is to big. It is just one pic.