Thread: CIS fuel head
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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,266
The gadget looks like a bosch L-jetronic fuel pressure regulator from the late 70's.
They were hooked up to the end or middle of the fuel rail and bled fuel off the rail and returned it to the tank maintaining base fuel pressure in the rail to the injectors at around 40psi with no intake manifold vacuum going to the vacuum connection, depending on the car it's made for.
Some guys looking to raise the fuel pressure would take two 3/8 drive sockets of the right size and place one at each end of it and squeeze the cannister in a bench vise to bend the side with the vaccum line inwards or slightly concave.
This would put more tension on the spring that pushes against the diaphram in side. The result is a slightly higher base fuel pressure.
Intake manifold vacuum also works with the spring to raise fuel pressure when accelerating and lower pressure when decelerating.

I read somewhere that Porsche and Bosch used the CIS fuel distributor from the early Mercedes 4.5 liter V8 and blocked off 2 of the fuel ports so only 6 remained... you can see where they were.

I know this doesn't help you much... just felt like adding to everything already said.
Old 12-03-2007, 02:22 PM
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