420 SBC project..was Re: selection of TBI components for 383 Chevy

[Curtis L. Martin]

> Curt, I'm interested in your 420 project and in particular what you
> plan for the fuel injection system (and the engine internals).
> Please email me directly if your comments are not related to 
> this forum. I am still seeking this groups input to help me select
> appropriate TBI components for a high torque 383 truck engine.
> Thanks for your input.  Steve

Sure,

The block is a 2-bolt 400 ('78 Blazer) bored 0.030" over and fitted with
Mildon splayed 4-bolt caps on the center three webs.

The rotating assembly was purchased as a kit from Larry's Performance Shop,
in California.  It consists of a 3.875" stroke, forged crankshaft, 327 5.7"
connecting rods, and custom JE reverse dome forged pistons.  It took a
while for the kit to get here, but so far it looks like it was worth the
wait.

Camshaft is a Crane 113801 camshaft (flat tapped hydraulic, 222 in 234 ex
@0.050 lift, 114 lobe separation, .467 in lift, .494 ex lift)

Cylinder heads are GM 10088113 Aluminum Center-bolts and are more or less
stock (valve diameters)  I just added Crane valvesprings, studs, and
guideplates.

I'm shooting for a finished CR in the 9.8 range.  The block is being honed
(in fact it should be done by now) so I'm waiting to see what the final
deck height is and compute the actual CR.  If it's over 10:1, then I'll
have to re-think a bit, take material out of the head chambers and use
thicker head gaskets to lower the CR.

Rocker arms are also Crane 1.6 roller. (These are left-over, narrow body,
non-self aligning rockers from my previous 2.8L, hence the guide plates. 
It was cheaper to buy 4 more rockers and add the guideplates, vs. a new set
of 16 self-aligning rockers.)

Timing chain is a toss up.  I have this Erson Gear Drive, but I'm debating
installing it.. might just go with a good old Cloyes double-roller chain. 
The good point about the Erson is that the cam cover is removable..
allowing a cam swap without disturbing the bottom of the motor.  I think I
will install it and at least try it out.. but at the first sign of trouble,
it'll get chucked in favor of a more traditional chain drive.

Induction is still an open issue...  The plenum/runner config I would like
is the TPIS Mini-ram.  The motor should have excellent low rpm torque
without relying on a long runner intake to enhance it.  I would rather use
the LT1 style short runner manifold and try to increase the top end of the
power band.

At one point I considered using a Holley 900 CFM Projection 4di on top of a
Weiand 142cid supercharger.  Holley's tech support killed that idea in that
they will not support or recommend blower apps for the 4di.  They would not
elaborate as to the reason why.  Based on displacement and a rpm limit of
5500 (self imposed..I'm not going to spin this motor to 7000rpm), 900 CFM
should be just about right. (or just 700cfm without the blower)

ECM is also a toss up.  There is a GP in process on the 3rd Gen F-Body list
for Haltech E6GM.  The other option is stock GM map ECM with a custom
calibration ala AS&M's CARprom.  At this point I'm considering doing both..
initially running the Haltech to gather data and define the basic fuel and
timing maps, then revert back to the GM module (using the information
learned in phase one as the starting point)  That will free up the Haltech
for the next project.  I get an un-easy feeling relying on an aftermarket
ECM for long term use.  My luck it will crap out at the most in-opportune
moment, leaving me stranded and unable to repair it.  At least with a GM
ECM, I can always scrounge one up in an emergency from a dealer, auto-parts
store, or junk yard.

Transmission will be a 700R4 with 2200 rpm stall converter.  Final gear
ratio is 3.42 with Auburn LSD in a 10-bolt axle.  The car is a 3400lb '87
Camaro.  The large amounts of aluminum going into this motor should lighten
the car down another 100 lbs, but I'm planning on adding a roll cage to it,
so the weight should remain about the same.

The car is currently MAF equipped, so that's going bye-bye, along with the
cold-start injector hardware, regardless of manifold choice.
(That reminds me.. I've got to go scrounging for a intake duct to replace
the MAF sensor... details, details, details..;-)

I have no idea right now on the selection of a knock sensor.  I guess all I
can do is use the GM 350 ESK module and hope for the best. (Suggestions
welcomed)

Ignition with be stock HEI.  I also plan to leave most of the emissions
gear that I have installed and functional.. which means having the
tube-steel headers equipped with a EGR flange, since the heads do not have
provisions for internal EGR.  I'm not looking forward to this.. probably
scrounge the basic plumbing off of a V6 Fiero or similar platform with tube
steel manifolds and external EGR.  (Fiero owners forgive me :)  Then have
the flange welded to the #8 cylinder exhaust header tube... similar to the
Corvette arrangement.

The car is also fitted with a CompuCar nitrous-oxide (wet manifold) system.

That's about the long and short of it.

Curt Martin (cmartin at america.com)
Ormond Beach, FL
http://www.america.com/~cmartin