4.3L TBI on 3.8L Engine ?

[Joe Boucher]

At 12:03 AM 10/18/97 -0400, you wrote:
>There is no way that a 4.3 manifold will fit a 3.8 engine.  The 3.8 is a
>Buick design, and the 4.3 is 3/4 of a small-block Chevy.  The architecture of
>each is totally different.  However, both are 90 degree designs.
>

I think we're loosing the bubble here and have missed the intent of the
original post.  Mr. Alford asked if a cheap 4.3 TBI could be adapted to a
3.8.  Taking the throttle body, wiring harness and the sensors off the 4.3
and adapting them to the 3.8 shouldn't be hard.  The worst part would be
making an adapter for the throttle body to replace the carb.  (I'm assuming
there is a carb on the 3.8, because if it has a tpi set-up, why bother!)

The one show stopper problem is the distributor.  There is no practicle way
to adapt the 4.3 distributor to the 3.8.  However, for a long time (most of
the 80's) GM used the HEI distributor without vacuum advance, or mechanical
advance, and a seven wire module to control advance.   If the 3.8 in
question has the HEI, then there is a chance it can be used.  Remove the
vacuum can, put a screw through the mechanical advance weights to freeze
them, and bolt in the seven wire module.  The big question is whether this
module can work with the 4.3 ecm.

If Mr. Alford is really interested, we need to know the year models of the
equipment.  Then I'll have to dig through a box of magazines to find the
diagram for the seven wire module.  There would be no guarentee about this
either.  A lot of this is a crap shot of one form or another.  You get an
idea, study it, way the risks, research the problems as best you can, close
your eyes and jump.  Then solve the problems you missed.  If anyone thinks
this is as easy as upgrading your radio, then you are in for frustration.
The swap of a TBI motor and overdrive transmission into my Suburban took to
two weeks longer than I planned and then a very long time to overcome the
electronic speedometer interface I missed.  Live and learn.

Joe Boucher
'70 RS/SS Camaro   '81 TBI Suburban
Joe Boucher
'70 RS/SS Camaro  '81 TBI Suburban