V-304A Engine

[n9ads@domain.elided (Howard R Pletcher)]

I just came across the following service letter that will answer some of
the questions about the "A" engines that have been asked.  This doesn't
address the V-345A at all, but I would expect it followed within a year
or so and incorporated similar changes.

SLM70-39
September 14, 1970

Release of Light Truck V-304A Engine for Scout, D-Line, and Metro Models.

Following is a list of features incorporated in the V-304A engine used in
the light-duty truck models listed above.

1. PISTON:

A cast aluminum piston less the top ring groove insert.  This type of
piston is typical of all competitive light truck engines.  The
elimination of the top ring groove insert in the piston reduces the
piston head temperatures by approximately 50 degrees.

2. CRANKSHAFT AND BEARINGS:

The new crankshaft is quenched and tempered in lieu of the present
version V-304 crankshaft which has induction hardened bearing surfaces. 
The bearing material used in the new light-duty truck engine is of
copper, lead, or aluminum alloy.  This material is considered a premium
bearing in the light-duty truck engine.

3. VALVES:

The intake valve material is of aluminized steel.  It is a standard
material normally used in light-duty truck engines.

A new type exhaust valve slow rotating device typically used in
light-duty truck engines will be incorporated in the V-304A cylinder
head.  Exhaust valve seats are machined directly into the cylinder head. 
The elimination of valve seat inserts reduces the valve head temperature
by 100 degrees and thus eliminates the need for stellite facing,
permitting the use of austenitic steel which is a reliable truck exhaust
valve material.

The exhaust valve positive rotators cannot be used with the light-duty
truck V-304A engine cylinder head, because the valves with positive
rotators will grind away the head seats without inserts very rapidly.

The seat width on the exhaust valves for the V-304A engine is 3/32"-1/8"
instead of 5/64"-7/64".  All other engine specifications for the V-304A
are the same as the V-304 engine.

The light-duty truck engine will be identified by "V-304A" stamped on the
serial number pad.

The V-304A engine will be serviced with the present V-304 engine
components, including single pistons or inserts, now in the service parts
system, except the exhaust valve positive rotators which are replaced by
a washer, IH No. 391 928 C1, and spacer, IH No. 391 932 C1, known as the
slow rotating device.

On the V-304A engine cylinder head where exhaust valve seats are worn
beyond reconditioning, it should be noted there is sufficient material at
this area to cut a counterbore and install a service V-304 exhaust valve
insert.

_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]