A-A-90
PARTS-SERVICE
Date: Apr. 20, 1985
Model: H30-60H D3
GRAM
Ford Cylinder Head
Subject: INSTRUCTIONS FOR ALTERING FORD 4.172 AND 4.192 CYLINDER HEADS
TO IMPROVE HEAD GASKET DURABILITY
Tools and Equipment Required: Drill press, 5/16" and 7/16" drill bits, 1/4" NPTF pipe tap, square, steel
rule, scribe or pencil, center punch or center drill bit.
Preparation: Remove cylinder head as instructed in service manual. Valve refacing, guides, or resurfacing
may be done before or after alteration.
Read instructions thru prior to starting alteration.
Step 1
Select a suitable work area. Place the cylinder
head with thermostat housing to the right side,
spark plug side facing up. (see picture) Note
the number four push rod hole, the oil supply
tube hole and the rectangular raised section of
casting between number two and three spark
plug cavities.
Step 2
Use a square and scribe to mark a vertical line,
showing the left edge of number four push rod
hole, just under the raised portion of casting.
(See picture.)
We reserve the right to make changes in design or add improvements without incur-
ring the obligation to make such changes in equipment previously manufactured.
H6030
Page 2 of 4
Step 3
Use a square and scribe to mark a vertical line
showing the right edge of the oil supply tube
hole.
Step 4
Use an accurate rule to measure the distance
between the two marks made in Step 2 and
Step 3. Divide this distance in half and mark
the cylinder head with a vertical line half way
between the two lines marked in Steps 2 and
3. (See picture.)
Step 5
Use your rule to measure 9/32" down from the
edge of the raised portion of casting along the
line made in Step 4. Center punch this spot.
This should center your drilling 9/32" down
from the raised portion of casting between the
push rod hole and the oil supply tube hole.
See Steps 5 and 6.
Page 3 of 4
Step 6
Chuck the 5/16" drill bit into the drill press.
Fixture the cylinder head so that the drill press
will drill in a true vertical manner and in the
center of the punch marked area. Drill until you
break into the cooling chamber. This will require
a drill depth of 1.5" or more.
Step 7
Chuck the 7/16" drill bit into the drill press.
Using the 5/16" hole as a guide, drill a 7/16"
hole to a depth of 1/2" to 5/8".
Step 8
Tap a 1/4" NPT hole to a depth of 3/8" in the
7/16" hole drilled in Step 7. This completes
alterations to the cylinder head until the head is
reinstalled.
Page 4 of 4
Step 9 With head reinstalled, install a 6 x 4 straight nipple, P/N 17352, into the tapped hole you have
prepared in the head. Note: If raised portion of casting interferes with straight nipple, casting
can be ground away for clearance.
Step 10 If engine is LPG equipped, remove the pipe tee from the rear of the cylinder head and install the
temperature sender directly into cylinder head. Discard original hose and fittings that went from
pipe tee to LPG vaporizer.
Step 11 Install an 8 x 4 reducing bushing, P/N 69815, and a 6 x 4 90 deg. nipple, P/N 17353, into the
IMPCO LPG vaporizer coolant inlet.
Step 12 Install a 3/8" I.D. hose between the 6 x 4 nipple in the cylinder head and the nipple in the coolant
inlet of the vaporizer. If the unit is gasoline, connect the hose from the cylinder head nipple to the
3/8" port on the inlet of the water pump. Hose should be of a material suitable for water glycol
mixture at temperatures of 275 deg. F. Note: Do not use gasoline fuel line.
Dealer installed or alternate brands of LPG systems may require different fittings. Alteration is
adaptable to all systems.
Interchangeability:
Not affected
Parts Stock:
Not affected
Effective Serial Number:
None