adjust fuel distributor

audiofilius · 06-12-2006, 06:21 PM

is a 1978 fuel distributor adjustable? I am getting varying amounts of fuel for each cylinder, even when i try different injectors.

Jim Williams · 06-13-2006, 04:52 PM

I assume you are checking the fuel flow by catching the injector outputs in separate containers, and then measuring each one. Are you saying that you swap the injectors between the 6 outputs and rechecking? If the flow from the different outputs on the FD doesn't follow the injector, but stays with the outputs on the FD, then this is a pretty good indication that the FD outputs are flowing different amounts.

I don't think the adjustments on the FD came around until maybe 1980. If there is no cap screw adjacent to each FD output, then the FD is non-adjustable, at least without taking the FD apart.

audiofilius · 10-13-2006, 04:31 PM

THere is a cap screw on top of each fd output. Is this supposed to be adjustible because it looks nonadjustible.

RarlyL8 · RarlyL8's Garage

You might try cleaning the fuel head. It doesn't take much of an obstruction to alter the delivery. There are a couple of threads on how this is done.

Gunter · Gunter's Garage

If the FD is dirty and clogged up on some of the lines, adjusting it will not solve the problem.
It might need a rebuild. The FD is adjusted for metering on a test bench.
Do a search on how some people dismantled and cleaned the FD.

audiofilius · 10-15-2006, 12:54 PM

..so what is the allen head screw, adjacent to each fuel line on the fuel distributor for?

audiofilius · 10-15-2006, 05:37 PM

I understand that prior to 1980 the fuel distributor was not adjustible. Anyone can tell me what the procedure is for adjusting this type of distributor?

regards and thanks in advance.

Jim Williams · 10-15-2006, 07:16 PM

According to the photo on my website, the adjustable FD came a couple of years earlier than I remembered off the top of my head. See page <http://members.rennlist.com/jimwms/CIS/CIShome.html> menu item "CIS Components", then scroll down the Components page and click on "Fuel Distributor". The caps I referred to in my earlier post are shown. The caps cover an adjustment screw which when turned clockwise increase the fuel flow. The screws press on a collar which in turn press on a spring which then pushes on the diaphragm at each fuel output connection. You would not want to do this without the knowledge of the proper flow for a given position of the piston and a way to monitor the flow at each output.

The folks that rebuild these things have that data, but I don't have the information to make this adjustment. You'd want to know that the adjustment was the problem, and not possibly a piece of trash blocking the flow at one or more fuel outputs.

audiofilius · 10-16-2006, 04:22 AM

I have opened up and cleaned the FD and am confident that the problem is not debris clogging the ports.
Has anyone had any experience adjusting the fuel flow?

Gunter · Gunter's Garage

These people have experience:

http://www.fuelinjectioncorp.com/products/distributors.php

audiofilius · 10-16-2006, 01:18 PM

mea culpa, I was under the impression that the 1980 and later years Fuel Distributors was adjustible.

T77911S · 10-17-2006, 03:27 AM

jim,

great web site. anyone wanting to learn about cis should check out the site. i have the bosch cis book and it doesnt explain everything about cis..the AUX AIR VALVE, DECEL VALVE and THERMO TIME VALVE. of which the connections ARE very important. until i took these 3 off and studied them and hooked them up to a vacuum gauge, did i understand their function.
thanks for another good site