Hello all. I have a 100% bone stock 1971 Z28 350 engine for my car, with 330 factory horsepower. This engine has everything 100% original.... solid mounted fan, (no clutch), points ignition, rear dump manifolds, factory aircleaner...

What will it take to get this engine to 400 hp ? It is 9.0 to 1 compression, with solid lifters.

Here are the engine specs:

Casting # GM P/N Description
Block 3970010 4 bolt main, suffix codes: CGP, CGR
Crankshaft 330550 Forged steel
Heads 3973487 75.47 cc, 2.02/1.6 valves, screw in studs & guide plates
Cam 3972182 3972178 symbol: (1) square Solid lifter - 0.458(I)/0.484(E) lift, 317I/346E duration
Pistons Flat w/valve relief - yields 9.0:1 compression
Intake 3959594
Carb (A/T) 3989022 Holley List 4800, 780cfm , 4150 series - 4BBL
Carb (M/T) 3989021 Holley List 4801, 780cfm , 4150 series - 4BBL
LH Exhaust 3989041 Rear exit, log type w/AIR, 2.026 outlet
RH Exhaust 3986330 Rear exit, log type w/AIR, 1.96 outlet
Distributor 1112049 Manual Trans, RFI, single point w/vacuum
Distributor 1112074 Auto Trans, RFI, single point w/vacuum


Alternator: Delcotron 37 Amp, part # 1100837
Water Pump: 3957170

Cylinder head has swirl polished valves and chrome valve stems.


Would I get it with a decent intake, headers, a electric cooling fan, and underdrive pulleys, and a HEI ignition ?

Any suggestions ?

 

You can get 400 BHP out of theis engine by bringing it up to spec ...( blueprinting, porting the heads etc)

You'd want to deck the block to make the stock pistons
come right up to the top of the block deck "Odeck"
You can "home port" the stock LT1 heads to increase the flow. 230+/180+ cfm is easily within reach.

With the block decking and head milling you can optimize the quench clearance and final compression ratio to optimize the output within the limits of the available fuel octane. ( 9.8/10.2:1 for 92 octane) .040 " total quench clearance.
The "nominal chamber" size is 76cc's. Yours may be more.
CCing and milling will get you to spec or a little less.

You'll need long tube 1-5/8" headers to reach 400 BHP
If the cam is worn you can replace it with a Crane "Blueprint" LT1 cam. You can get some more power by going to a modern version of the factory solid cam with the same .050" specs but more rate of lift and total lift.
Upgraded springs will be nessessary. ( crane 99846)

use crane #114681 for improved power from stock.
( its very simular but has more lift and action)
or crane blueprint #969551 if you want to stay origional.

Carefully "port match" the factory LT1-Z28 hirise intake manifold to the heads port openings.

A MSD "ready to run" hi perf electronic replacement distibutor would be a great upgrade to the factory distributor. It uses the same style cap as the old point distributor. its self contained (no box required) (needs a true 12v B+ supply thou. Eliminate the ignition resistor on old cars (pre 1975)