[Gmecm] TBI Swap - Iron Duke Tech IV

Mon Feb 13 15:07:49 UTC 2006

For the 2.5, it would be bunches easier to just use the 2.5 TBI
distributor...
For the 250, Use the HEI distributor, swap in a 7-pin module in place of
the 4-pin, lock down the advance, and then match the connector on the
harness, if needed.

But the rest of the info is good for if you're trying to hook this up to
a non-GM engine.

This brings about a question; Did you get everything from the Olds
you're going to need, all the sensors, distributor, etc? What are you
going to do for VSS? Be sure to change out any pieces of rubber fuel
hose with the higher-pressure stuff so it doesn't blow apart once it
gets pressurized.

Good Luck,
Joel

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On
Behalf Of gmecm-request at diy-efi.org
Sent: Sunday, February 12, 2006 12:03
To: gmecm at diy-efi.org
Subject: Gmecm Digest, Vol 12, Issue 18

Message: 2
Date: Sat, 11 Feb 2006 21:44:50 -0800 (PST)
From: Andrew Gibson <andrewsharyn at yahoo.com>
Subject: Re: [Gmecm] TBI Swap - Iron Duke Tech IV
To: gmecm at diy-efi.org
Message-ID: <20060212054450.8215.qmail at web60818.mail.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"

I'm glad I'm not the only one trying this conversion! Only mine is going
on a 250 CID Chev 6 cyl. Mechanically you sound fine. For your fuel flow
the large steel line going to the throttle body is pressure, little one
is return. Any excess/unused fuel is returned to the tank. You may be
able to raid the fuel lines and pump off the olds and make them work on
your jeep. (PS: the carb has a float to prevent too much fuel inside the
bowl. Just like your toilet at home)

  The most difficult task to conquer is your rpm feed. You may be able
to attain spark control (Computer controlled timing) as well with this
setup, but I haven't dug into that yet. I'm still researching and
testing. For simplicity, there is a 5 wire connector with 4 wire in it
that attached to the ignition module. Cut it off. Locate a unsuspecting
gm tbi vehicle in your local boneyard and remove the two electrical
connectors from the module and cut them with about 6" of wire on them.
Visit the parts store and get a ignition module and pickup coil for a
4.3L v6 roughly the same year as the donor of the connectors. (Or just
skank them while at the wrecking yard.) Solder the 4 wire connector onto
the wires of your harness where I told you to cut them off. The colors
will match! Cool huh. It gets better. The 2 wire connector from the
wrecking yard needs to be attached red to switched positive (The other
old ignition module connector has this! Same color too!) white is coil
negat  ive if  you want the computer to do spark control. If not seal
the end up with heat shrink tubing for later use, just in case.

  Mount the module somewhere safe (Firewall is good) with carefully
tightened self tapping screws and dielectric grease on the underside (It
grounds and transfers heat there) Cut the pigtail off the ignition
pickup. Inside your distributor there should be a ignition pickup. If
using the ecm for spark control, cut off the wires to the pickup at the
connector and solder & heatshrink 2 longer wires to the pickup. Twist
the two wires around each other to reduce noise and solder your donor
connector on. Plug it into the module with dielectric grease to prevent
corrosion. If you are going to use existing spark control just splice
the longer wires onto the module wires and run them. MAKE SURE YOU DO
NOT PINCH THE WIRES WHEN RUNNING UNDER THE DISTRIBUTOR CAP! Cut a notch
in the cap if you have to.

  One other item. IF you are going to use the ecm for spark control. The
advance mechanisms in the distributor must be locked solid. This
includes the centrifigul advance under the rotor and the vacuum advance.
If not hook your advance vacuum hose up appropriately at the TBI unit.
There are two vacuum sources, ported and manifold. Either one could have
been used. Mix it up and it will not run right.

  Good luck and keep us posted!