Crate Motor Selection and Installation
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I selected the GM ZZ383 Crate Engine 425HP 12498772
motor in July 2006. I placed the order with Jeg's, primarily because
of a $350 price increase on July 1st at Summit, my preferred performance
parts vendor. Summit says they will match the price but I was afraid
Jeg's would also increase the price. It's probably a pass on
increase from GM. All sources I checked were equally high except
I like the torque and horsepower. Another reason
was the requirement to support the smog equipment (EGR) on the intake.
Some of the motors come with intake manifolds but not with EGR support so
it has to be replaced. It should be noted here that it is likely
that the EGR will be for appearance only.
I also own a new Holley spreadbore
carburetor that I need to use. All the engines that came with the
intake installed only supported the standard bore carburetor.
There's no room to add an adapter under the hood of a 77 Corvette.
The engine will be mated to
a new Keisler / Tremac 5 Speed. Installation of the Keisler kit is
discussed in the How To section.
The engine is basically a long block assembly.
Additional parts are required for assembly. Ordered the following:
- Intake - GM 12496820 - Lo Rise
with EGR - Vortec design - Std or Spreadbore carburetor. This is
what you want if you want to keep your EGR valve and use a spreadbore
carburetor. Exhaust gases for the EGR do NOT come from the cylinder
heads. There is no crossover support on these heads. If you
need to connect to the exhaust for the EGR, you do it through a
connection at the front of the manifold near the thermostat. I am
not sure how I'd do this
with stock exhaust manifolds on a 77. The treads for this input
are a strange size I have not identified. They are close but
slightly larger than 1/2" NPT. This port and the EGR mount must
be closed or you will have a vacuum leak.
- Distributor - GM HEI
- Thermostat housing - Mr. Gasket
- Fuel pump - Stock Carter
- Fuel pump rod
- Water pump - Edelbrock
- 2x Dorman original style exhaust manifolds to
be ported to match D ports on heads
- Intake and exhaust gaskets
- Heat riser eliminator spacer
- Chrome / aluminum valve covers
My Selection Criteria
GM Crate Motors are available from a number of sources.
My primary supplier is Summit but I bought just the motor through Jeg's
due the recent price increase.
My primary reason for replacing the engine was
reliability and the uncertainty of the current engine. I didn't know
the history of the current car. The motor looks like is was rebuilt
not too long ago. It seems to have no problems other than very minor
(1 drip/day) oil leak and a slight lifter tick. With the vehicle headed to Europe soon, I
decided it was cheaper and easier to replace it while it was still in the USofA.
Choosing an engine to replace my existing L-82 was no
easy task and it is full of compromises. Gas mileage is a factor
given it's eventual home. That's partially offset with the
installation of the Keisler 5-speed kit.
Reliability is a concern. That's my reason for
picking a new engine instead of rebuilding the original L-82.
Vehicle inspections in Spain can be tough on little things you don't run
into in the USofA. They don't like oil leaks.
Ease of installation is important. I don't have
the time to make any modifications in the fit and operation.
Accessory drive brackets must fit. SMOG equipment must be
maintained, at least while it's here in the Peoples Republic of
My final candidates
|Chevy 350, 330 hp
Cast Iron Vortec Heads
|ZZ4 350 C.I.D. 355 HP Engine
||HT 383 C.I.D. 340 HP Engine
||ZZ383 C.I.D. 425 HP Engine
Chrome valve covers
- Chrome valve covers
- Intake included - But No EGR support
- Harmonic Balancer included
- Distributor included
- Roller Cam
- 9.1 Compression
- High 435 Ft/Lb Torque
- Intake included
- Roller Cam
- Harmonic Balancer Included
- Plugs included
- 449 ft./lbs. Torque
- Lots of HP
- Roller Cam
- Aluminum Roller Rockers
- Dual bolt pattern fast burn aluminum heads support
both Vortec and Standard intake manifolds.
- GM Intake available for EGR support and it fits
under Corvette hood
- Harmonic Balancer Included
Bare engine - needs $1000 in additional parts for
intake, distributor, water pump, balancer, and fuel pump.
Unable to find an intake manifold that works with
the Vortec heads that supports EGR valves.
- 10.1 Compression - Premium Fuel
- Long water pump - not usable on Corvette
- Harmonic Balancer not usable - 8" - Need 6 3/4"
- Cost over the 350/330 for small HP gain.
- Power is in the low end - Trucks and towing
- Painted Valve Covers
- Aluminum head reliability? Personal concern.
- Painted Valve Covers
- Exhaust Manifold needs to be ported to attempt to
match large D exhaust ports. Vortec and "882" heads are
- Bare engine - needs $1000 in additional parts for
intake, distributor, water pump, and fuel pump.
The newer motors might not be compatible with existing
parts or you might be converting from Auto / Manual shift. In my
case, the existing flywheel is not compatible with the newer SB design.
I ordered new components from Keisler Engineering along with the 5 speed
Old parts look really bad installed on new parts.
I took the opportunity to replace the Bellhousing and Exhaust Manifolds
with brand new parts.
- Flywheel (required)
- Clutch Assy (easy to do)
- Bellhousing (cosmetic)
- Exhaust Manifolds / Headers (cosmetic / performance)
- Water pump (required if motor is supplied with long
You run into "things" needed to finish the job.
Here are some of the little things I needed.
- Spark plug wire holders compatible with the
centerbolt valve covers and stock exhaust manifolds. I
picked the Russell parts but had to make some major modifications.
The modifications have been described on this site.
- 7/8" Plug for the intake. See below
- EGR block plate and gasket.
- Compatible carburetor mounting studs.
This was a PITA because of the Holley Spreadbore I used. Had
to grid some down to fit.
- Fuel line
- Remove old engine
- Replace with new engine
- Test drive!
Ok. Greater detail will be provided at the end
of the project.
- RAM's Horn Exhaust Manifolds
They bolt up
but the square ports don't match the new heads. You need to do a
bit of grinding to come close to matching the "D" ports on these engines. You will not have 100% match but you can get close.
Pictures and procedure is published on this site.
There is no exhaust
crossover provided with these heads. The Heat Riser on the right
exhaust pipe just below the manifold must be removed or blocked open. If not, there is no
place for the exhaust to go when the engine is cold and the valve
closes. I ordered a crossover eliminator from Ecklers Chevy (not
Ecklers Corvette - Same company, different catalog). There is no
exhaust for the EGR valve either.
The intake I ordered supports using the EGR
valve. The exhaust gases must be plumbed into the intake
near a 7/8" pipe behind the thermostat housing. If you are
not using the EGR, you must plug this opening and use an EGR block
plate. 7/8" plugs are not that common. I ordered a GM
Performance Parts piece from Summit. Costs almost $20!
- Water pump must be replaced
comes with long nose style. Corvettes use short nose.
- Composite timing cover interference with short
nose water pump
There is a clearance problem with one bolt
on the timing cover behind
the inlet on the passenger side. Make sure you buy an Edelbrock water pump
or one that is guaranteed to work with the composite cover.
Edelbrock has been modifying their pumps to be compatible with the composite
cover since January 2006. It's July 2006 when I'm writing this and
many people are not aware of this change to their pumps.
It has been recommended by some
to replace this hex head bold with a button head allen design. I
didn't try but a quick visual check during the install tells me it
other option is to replace the composite cover with the older metal
design. I didn't like the idea of cracking open a new sealed
engine and risk oil leaks.
Now you don't have to do anything
except order the right pump.
- No fuel pump rod for mechanical pump
You need to order a fuel pump rod or use an
existing one. You also need the mounting plate that goes
between the engine and the fuel pump. They ZZ383 comes with
a block-off plate. I have no idea where you find a new
plate. I used the existing plate from my stock motor.
There's a problem mounting it to the Vortec style manifolds. No
bolt. If you are running without a pump, no problem. If you
want to run with the pump, it's going to take some grinding to make this
- AC support bracket that is next to the valve
There is no place to mount this on a Vortec style manifold. I will
run without it. If you use the older style 12 bolt intake. the
bolt is there. I considered drilling and taping the Vortec
manifold but I don't think this support is really required. It is
now mounted securely. No flex. No vibration.
If you have flywheel from the older
2 piece rear seal type of engine, it won't work. You need the
newer externally balanced flywheel.
Bellhousing and inspection plate
The inspection plate from the two piece rear
seal blocks won't fit the newer one piece rear seal blocks.
You have to cut out several areas on the inspection plate for
extra clearance. First, enlarge the semi-circle that goes
around the rear seal. I cut away about 1/4" with tin snips
then cleaned it up on the bench grinder. Next, test fit it
and you'll see other areas where it will interfere with the oil
pan. Trim those too.
- Temperature sender
The sensor from the existing L82 and early 350's
won't fit into the treaded hole in the head. It has the wrong thread size. The stock sensor
through 1980 requires
1/2" NPT threads. The Fast Burn aluminum heads are tapped for 3/8"
NPT. So you have 2 choices. You can relocate it to the
intake or find one with 3/8" NPT that works
with the existing gauges.
Old Sensor Left / New Sensor Right
I unsuccessfully tried to use the sensor from a 1981-82 Corvette.
This sensor uses 3/8" NPT threads. I
bought an AC Delco 25036135
coolant temperature sensor. The cost was about $35. It comes
with the .24" blade connection too. This sensor seem to be
calibrated differently. It was reading 20-25 degrees too
cool. There is a possibility that this could be corrected
using a different resistor on the back of the temperature gauge.
Maybe someday. I've already installed the center gauges for
the 5th time! If I have it out again I'll give it a try.
For now, I'm using the sensor as a $35 plug to keep the coolant in
Solution? I relocated it to the
thermostat housing. There is normally a vacuum valve here used by
the smog equipment. This car will not be required to pass a
smog test where it is going.