Running a 305 with '747

[dave.williams@chaos.lrk.ar.us (Dave Williams)]

-> I am considering swapping a 305 motor into my 87 Astro van. It
-> currently has a 4.3 TBI setup on it

 I'm finishing up one of those now.  It's a '93 conversion van with oil
cooler, rear air, and rear heater.  It's a mess of hoses and junk under
the hood.

 We put an '85 350 in.  Ron had found some motor mount drawings on the
Web; they were fairly close, though they required some extra clearancing
here and there.  Note:  just grind those stupid 1/4" steel tabs on the
chassis mounts.  There was some controversy over dropping the entire
cradle and powertrain out the bottom or pulling the bumper and grille
and coming out the front.  Ron complained bitterly when I insisted on
pulling it out the front; I didn't want to try to jack a thousand pounds
of iron two feet into the air and line it all up under the van.  Turned
out it didn't make any difference; 99% of the work was disentangling the
Rubik's Cube jungle in the engine bay.

 I slotted the TBI intake holes so the center bolts would work with the
'85 heads.  Lots of people apparently just crank down the bolts and let
them cut divots into the aluminum, but the 15 degree mismatch was too
much for me to accept.  I made some wedges to go under the bolt heads.
Then we tried to bolt the accessory brackets on - huge aluminum castings
on each side.  The passenger side holds the alternator and idler
pulleys.  Old SBC heads have no bolt holes.  Around '68, they went to
three at one end, one at the other.  It turns out they went to three at
*each* end in '86, so there was only one bolt in the head and three
holes in the bracket.  One missing bolt hole could be drilled, but there
was nothing anywhere near the other.  I made a plate of 3/8" steel with
the proper '86 hole positions and used it as a template to drill the one
hole, then drilled and tapped the head for a few extra holes for
countersunk Allen screws for a little extra support.  The end of the
head casting is fairly thin, no bosses inside for the missing bolts, so
I added the extras.  Then I had to mill 3/8" off the back of the
alternator bracket, which required lots of ingenuity fixturing the
bizarre sumbitch on the mill.

 Frankly, I should've pulled the '85 heads and built up a set of center
bolt heads, but I was on a roll.

 The '93 TBI 4.3 intake had bosses for the support brackets, MAP sensor
bracket, coil bracket, etc.  The '89 TBI 350 intake has bosses... but
they're nowhere near the 4.3's, nor are they at the same angles.
Fortunately the only thing that looks critical is the rear stay for the
air conditioning compressor.

 The 4.3's knock sensor went into the bellhousing flange below the
distributor.  I drilled and tapped the 350 block to match.


 If you ever need a 747 wiring harness, you want one off an Astro!
Unlike the others I've pulled, the Astro can be done in minutes.  Pop
the hood and engine cover, disconnect the sensors, unclip the harness
from a few brackets, pull the C-clip holding the plug at the cowl, pop
the computer out of the kick panel, and feed the wires through the cowl
hole.  Some car harnesses require hours of destructive disassembly...
                  
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