Making a Cut-out Raiser
Because of legalities, I can only suggest this as an off-the-road mod. Attempt this at your own risk. It's possible to screw up your engine if you're "all thumbs", and tend to mess up instructions! If you don't want to be adventurous and make it yourself, click on the "Dawes Devices" link, farther below.
the un-modified valve as part number: 48935K25
Modify as follows:
First take the stock valve, disassemble it by unscrewing it, and re-assemble it with the steel ball moved to the OTHER side of the spring. The steel ball will now be on the red-threaded end of the valve.
Then get a screw-on barb (McMaster-Carr part# 5346K51) and screw it onto the red-threaded end.
...and put together a couple of short pieces of vacuum
line, a tee, and a restrictor orifice (brass piece with pinhole in
I pick up welding tips at a local welding store. That's one in the picture above. Below is a completed valve.
WARNING!! The restrictor orifice
(or welding tip) should be .040" to .050" A small orifice, like some stock ones,
will cause the "check engine' light to come on. The illustration above shows
.035" as the smaller limit, but actually .040" to .050" is better.
DawesDevices sells my cutout raisers to fellow Mopar enthusiasts (all ready to go).
If you have the old style
logic-module-in-the-kickpanel setup, then you put this device in the car, or
In the car: splice into the vacuum line that goes to the MAP sensor - logic module. Pull back the passenger's side footwell carpeting, or remove the kick-panel. Splice in the cut out raiser with the white nylon connector facing the MAP sensor. Of course the brass restrictor points the other way! ; )
DIALING IN the installed unit
After installation, screw the knurled knob almost all the way in, and the car will still cut out around 15 psi. Loosen the lock-ring, and unscrew the knurled brass knob a half-turn. Re-tighten the lock-ring. After you do this a few times, you’ll notice that the cutout point gets higher. You can stop at 16, or 18, or whatever you want. BUT, the higher you go, the more fuel you have to add.
Set it as low as you can get
away with, because your computer will give you NO MORE fuel past14.7 psi. The
computer will believe that you’re never going over 14.7 psi!
If you have a rich-lean gauge, back off when the gauge indicates that you are NOT rich!
If you have no gauge, run a wire from your O2 sensor wire (the one that reads .1V-.9V at warm idle, bouncing up and down) through the firewall, into the car. Hook the O2 wire to the red probe of a digital voltmeter; hook the black probe of the digital voltmeter to a clean ground. When you floor it, you want to see .87V to .97V. Less than .87V means you’re not safely rich. Back off, and add fuel.
You can add fuel by raising the fuel pressure, adding an extra injector, or switching to slightly larger injectors. If you don’t add any fuel, don’t run high boost! I can usually run 15 psi on the stock setup.
Do NOT open the valve much to start with. Just
open it enough to bring your cut out point a little higher. The brass needle
valve can be replaced with another simple restrictor orifice. The smaller the
orifice, the less raising of the cut out point; the larger the orifice, the more
raising of the cut out point.
If you are running computer controlled boost, this needle valve mod will *also*raise your boost level!
I designed this set up for manually boosted cars. Computer controlled car swill see a rise in their boost. Will make a fun experiment. Just go easy on the throttle 'til you see where your new boost level is. If you don't bleed much, the boost won't go up much. And you *don't* want to bleed much...