Swapping Engines


Ever since the introduction of emission controlled engines there
has been much discussion on how this affects swapping engines
among different vehicles and/or model years.  

According to the Federal EPA the following facts apply:
o            Every vehicle sold in the US has an engine or engine-chassis
design which has been certified by the EPA.  This certification
has been achieved prior to production of the vehicle and is based
on a Federal Test Procedure (FTP).

o            EPA policy states that any modifications to a certified
configuration would be considered tampering unless there is a
reasonable basis for knowing that vehicle emissions are not
adversely affected.  Use of the FTP may be necessary to make this
determination.  However, EPA's tampering enforcement policy
states: ... the permanent removal or disconnecting or blocking
of any part of the original system primarily installed for the
purpose of controlling emissions will be presumed to affect
adversely emission performance ...

o            Any engine being installed in a vehicle must provide at
least the same amount of emission controls as the certified
configuration for the model year. For example:  A 1984 Chevrolet
Caprice was available with either a 5.0 or 5.7L (305 or 350 CID)
engine.  If one engine is replaced with the other, all of the
related emission control devices, including the computer, will
have to be changed in order to be in compliance with EPA.

o            Installing a new engine in an earlier design vehicle is
permitted as long as all related components from the new model
year are used.  

o            Installing an older engine in a newer design vehicle is not
permitted.  

o            Installing any engine without reinstalling all of the
emission control equipment, the way it originally came from the
manufacturer, is considered tampering.  This also includes
modifications to the exhaust system, such as changing from single
to dual exhaust unless there was such a certified configuration. 
In each case the installation facility may be cited by the EPA.

o            Replacing a diesel engine with its gasoline counterpart must
include installation of all of the emission control equipment. 
Even the unleaded gasoline only restrictor must be installed in
the fuel tank inlet.

o            The EPA does not accept an exhaust gas analyzer test in lieu
of their FTP test for non-certified configurations.  It is the
responsibility of the installation facility to have the vehicle
tested according to the FTP.


                                                                    
The AERA Technical Committee


October 1990 - TB 707

##END##

                       Crankshaft Thrust Wear On
                      1994-96 GM 4.3L V-8 Engines


AERA members have reported excessive crankshaft thrust wear on 1994-
96 GM 4.3L V-8 engines. This engine is used in Chevrolet Caprice
cars and many of those are in taxi-cab fleets. These cars often
obtain high milage in a short period of time and many are currently
being rebuilt. AERA members have noticed abnormal thrust wear on the
crankshaft cast #10168568, as those engines are disassembled.

In some instances, those vehicles may have already required
transmission service and have had the torque convertor replaced. GM
engineering has expressed to AERA that the torque convertors used in
these vehicles are not the same as previous designs. This
application requires additional internal reinforcement of the torque
convertor. If a torque convertor for a different application is
installed into this vehicle, the converter may expand and cause the
crankshaft to be forced forward. The torque convertor for this
engine, Part #24202174, is also used in high performance engines.

                                         The AERA Technical Committee


April 1996 - TB 1332


##END##

                New Lightweight Piston Design on
                 1990 GM 5.7L (350 CID) Engines


General Motors Corporation has introduced a new lightweight
piston design for 1990 5.7L (350 CID) engines used in the
Caprice, Camaro and Corvette.

The new piston is a low friction, flat top design and is not
interchangeable with previous designs.  At a weight of only 540
grams, the piston should improve engine fuel economy.  Depending
on cylinder head combustion chamber design, the new piston
results in a compression ratio of 10.25:1 on the Corvette and
9.75:1 in the Camaro.

The ring set for this piston is also new and does not interchange
with the former design.  The top compression ring is 2mm thick
while the second ring is 1.5mm thick.  Both rings have a narrower
radial width and shallower groove depth than previous.  The oil
control ring assembly now measures 4mm in thickness and is also
new for this piston.

While the piston to cylinderwall clearance remains unchanged,
.0007-.0017 (.017-.043mm), it is now measured at .450 (11.5mm)
above the bottom of the skirt (see illustration).  The
barrel-shaped piston skirt cannot be measured for taper.


                                     The AERA Technical Committee


September 1990 - TB 691

##END##

                                              Revised Thermostat For
                                    1989-90 GM 5.7L (350 CID) Engines

General Motors has released a revised thermostat for 1989-90 Chevrolet Caprice automobiles equipped with 5.7L (350 CID) (VIN Code 7) engines.

Engines in these vehicles may run hot during extended low RPM or high speed operations.  The revised thermostat, Part #10108666, features improved coolant flow characteristics and a quicker opening rate to increase engine cooling.  This thermostat does begin to open at 195oF, but reaches its fully open state more
quickly.

The Chevrolet Caprice is very popular in commercial, taxi and police fleets.  AERA members servicing these accounts may recommend installation of the revised thermostat to guard against premature engine failure.

                                                                           The AERA Technical Committee

                           Valve Crosshead To Rocker Lever Clearance On
                              NH, NT & V-1710 Series Cummins Engines

Valve crosshead nose to rocker lever clearance on the subject engines must be checked during engine rebuild and at any time valve crossheads are replaced on engines using crossheads No. 123416 & 3000326. A minimum of .020 (.51 mm) clearance must be present as illustrated in Fig. 1, on the cylinder being checked with valves completely closed and crosshead in the upmost position. After installing rocker lever assemblies, check crosshead to rocker lever clearance as follows:

1. Turn crankshaft slowly in direction of rotation until the valves are closed on the cylinder being checked. With rocker lever held firmly against the stellite pad of the crosshead, a .020 (.51 mm) wire type feeler gauge must pass between the crosshead nose and the lower beam section of the rocker lever.

2. If the feeler gauge does not pass through:

a. Remove the rocker lever and/or crosshead and grind the nose of the crosshead or 	rocker lever beam in the area circled in Fig. 1 until enough clearance is obtained.

b. If the rocker is ground, grinding should cover the complete area illustrated in Fig. 2 in a continuous arc. Do NOT grind just the contact area.

Caution: A sharp depression in this area will cause a stress riser and eventual failure of the lever. Grind only enough material to achieve the required clearance. If grinding enters the oil passage, the rocker lever must be junked.

c. Grind sharp edges smooth.




                                                                   The AERA Technical Committee

Crankshafts Used In Industrial Applications On
GM (Chevrolet) 5.7L (350 CID) Engines

When the GM (Chevrolet) 5.7L (350 CID) industrial engine is used in some applications such as lift trucks, the only crankshaft that is applicable has the forging number 1182.  Dimension A of the rear flange is slightly smaller than that of other crankshafts used in General Motors 5.7L (350 CID) engines.

The larger flange crankshafts will not pass through the center hole of the bell housing.  This is very critical when an oil clutch system is used.

                                                                     The AERA Technical Committee

Burned Exhaust Valves, Low Power & Hard Starting On
Cummins NH & NT Engines With Jacobs Brake 25B & 30

Cummins Engine Co. reported that if the following complaints are experienced in the NH and NT engines equipped with Jacobs brakes, the slave piston clearance should be checked:

A. Exhaust valve burning

B. Low engine power when at operating temperature 

C. Engine hard to start or will not start at operating temperature

A standard slave piston adjustment of .018 +/- .001 has been established.  The .018 clearance setting is a cold setting which results in zero slave piston to crosshead clearance when the engine is at operating temperature.

Should the slave piston clearance setting be less than .018, the following conditions outlined in A, B or C above may result as well as affect breaking power.

If the slave piston clearance is greater than .018 +/- .001, the following problems may occur:

1. Engine injector train component problems
2. Injector carboning
3. Bent injector push rods
4. Worn injector adjusting screws
5. Decreased camshaft life
6. Cam follower and follower shaft failure
7. Delay in breaking action

If the above problems are experienced and the engine is equipped with a Jacobs brake, the slave piston clearance should be checked with the latest Cummins specifications.

                                                                     The AERA Technical Committee

                                      New Cylinder Liner O-Ring Seals On
                                      Cummins NH/NT 6 Cylinder Engines

Cummins Engine Company has released new O-ring seals for the cylinder liners in NH/NT 6 cylinder engines.  The new seals are made of an EP material and have a smaller diameter cross-section.

The new seal replaces both the old center seal #3008998 and the old lower seal #183049.  The new seal carries Cummins part #3032874 and is black in color with one blue dot.

The new O-ring seals are not to be intermixed with the former seals on the same liner.  Cylinder liner deformation will result.  You can use the former seals and new seals in the same engine as long as they are used in the correct combinations on each liner.  The illustration below shows the correct combinations.

                                                                       The AERA Technical Committee

                                               Oil in Cooling System on
                                         VW 1.5L & 1.6L Diesel Engines

AERA members have reported instances of engine oil in the cooling system on VW 1.5L diesel engines.  According to AERA sources, the problem is related to a crack in the cylinder head bolt hole located near the oil gallery feeding the cylinder head.

The oil feed gallery in the block is located on one side of the center head bolt hole and a coolant jacket is on the opposite side of the bolt hole.  Pressurized engine oil is diverted through a slot in the head gasket and is feed up the side of the head bolt to the cylinder head.  The oil also follows the bolt back down to the bottom of the bolt hole.  Should the crack in the head bolt hole extend to the coolant jacket, oil can mix with engine coolant.

This problem is generally found on engines equipped with 11mm head bolt holes.  Later design engines utilize 12mm head bolts and do not exhibit this defect.  At the time of this writing no successful repair procedure is available.

                                                                       The AERA Technical Committee