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Rebuilding the Ford 4.6L SOHC Engine
by Doug Anderson
The 4.6L Romeo
SOHC was introduced in 1991 as the first born in an all new family of engines
for Ford. It had a rigid, deep-skirted block with cross-bolted mains, long rods
that gave it a favorable rod length-to-stroke ratio, a lightweight crank and
pistons, and SOHC aluminum heads that incorporated all the latest engineering
theory with ports and chambers that were designed to make more power with fewer
The 4.6L was
lower, shorter and lighter than the 302, but the base engine made more power
than the 302, got better fuel economy and passed all the emission tests without
a thermactor pump. Ford called it its "modular" engine because it was part of a
whole new family of engines that were intended to have a common architecture "so
they could share similar production tooling and have many interchangeable
The V6 that was
originally intended to be part of the modular program never did get built, but
there are several engines in the V8 family, including one 4.6L DOHC and two SOHC
motors, along with the 5.4L V8 and the 6.8L V10 that are all part of this
idea of a standardized, modular engine looked good on paper, it hasn’t worked
out quite as well in the real world, because there have been many changes that
have created lots of variations over the last 10 years.
The 4.6L engines built in the Windsor plant are
completely different than the ones built in the Romeo plant, and there are
significant differences in the engines that have been built in each plant from
year-to-year, so there are at least eight short blocks, seven heads and 13 long
blocks so far, not counting the CNG and DOHC engines.
confusing to keep track of all the different combinations, so nobody seems to
know what goes where or exactly when it was used. We tried to get some help from
Ford, but we were unable to find anyone who was willing to share any
information, so everything in this article is based solely on what we have seen
and pieced together along with the help of some other people in the industry.
We believe that
what we have figured out so far is pretty accurate, but we know there’s more to
the story because
we learn something new on a regular basis, so start with what’s here and build
on it with your own experience.
disclaimer in mind, let’s take a look at the 4.6L SOHC modular engine and walk
it through, year-by-year, beginning with the blocks, and see what Ford has done
with these engines from 1991 through 1999, keeping in mind that the CNG and DOHC
applications aren’t included in this discussion.
have been two distinctly different cast iron blocks used for the 4.6L, depending
on whether the engine was built at the Romeo plant or the Windsor plant. There
are two Windsor blocks with two casting numbers and one minor difference, and
there are four different versions of the Romeo block with several different
1991 – 1992
original Romeo block was a F1AE casting that can be identified by the solid
dowels that were used for the automatic overdrive (AOD) transmission, along with
the shape of the bellhousing that slopes down from the deck to the edge of the
rear seal retainer at about a 30 degree angle on the passenger side. The first
four mains are cross-bolted with "jackscrews" between the block and the main
caps, but the rear main isn’t cross-bolted. This block was used through 11/1/91
in the Lincoln Town Car and through 2/18/92 for the rest of the Ford and Mercury
cars that came with the 4.6L engine.
1992 – 1995
block replaced the original casting when the AODE (automatic overdrive,
electronic) transmission was introduced late 1991 or early ’92 in the RWD Ford
and Lincoln/Mercury cars (See the dates in the above paragraph). It was
superseded by the F4VE casting that was identical to the F2VE in 1994. These
blocks can be recognized by the hollow dowels that were used along with the AODE
(automatic overdrive electronic) transmission and the semi-circular boss for the
starter that was added on the right side of the bell housing
The corner of
the block is reinforced by a triangular web that is parallel to the pan rail and
perpendicular to the front of the bell housing, too. And, these blocks still
have only four cross-bolted mains instead of five like all the later Romeo
1996 – 1998 Romeo Car
third Romeo block was introduced in 1996. There have been three different
casting numbers including the F65E-CC, F6VE and F7VE, but all three blocks are
the same. These blocks have five cross-bolted mains instead of the four that
were found on the earlier blocks, and they have a threaded hole in the valley
for a knock sensor.
The freeze plug
on the driver’s side was moved up closer to the deck and the bolt for the front
cover that’s right beside the big hole for the water pump was moved up about
.250˝ closer to the deck, so it’s located at 2 o’clock instead of 3 o’clock when
facing the block (see photo below).
appear to have been used for the 1996 and ’97 cars (the "V" in the casting
number indicates that the casting was originally designed for a Lincoln) and the
1997 pickups that were built in 1996 and titled as ’97s (the "5" in the casting
number indicates that it was intended for the pickups).
This block will
work in all of the RWD cars including the Fords, Lincolns and Mercurys, and in
some of the trucks, too, but it won’t work in all of the trucks because it
doesn’t have the extra bolt hole between the second and third soft plug on the
driver’s side that’s used for the oil cooler that was included with the optional
trailer towing package on the trucks.
By the way,
there are some Crown Victorias with the Police Interceptor package that have an
oil cooler, too, but it’s mounted under the radiator, so this block should fit
all the cars up through 1998 or ’99.
1997 – 1999 Romeo Trucks, Vans, Expeditions and
According to the F7AE casting number, this block was designed for a 1997 car, so
it probably was used in some cars along with the F7VE block, but we believe that
it was the primary block for the 1997–’98 pickups, vans and Expeditions until it
was replaced by the XW7E casting in 1999.
Both of these
castings, the F7AE and XW7E, have a second bolt hole under the existing one
between the second and third soft plug on the driver’s side. Both of these holes
were used to mount the extended housing that moved the oil filter to the back,
closer to the bell housing, so there was enough room for the oil cooler that was
part of the optional trailer-tow package on the trucks and Expeditions.
Since most of
them came without the trailer-tow package, and it seems unlikely that Ford would
have had the same engine with two different castings waiting on the assembly
line, we believe that the F7AE block was used in most of the pickups, vans and
Expeditions through 1998 until it was replaced by the XW7E casting in 1999.
1996 – 1999
F65E-BB and F75E castings are the only Windsor blocks that have been used
through 1999. Don’t confuse the F65E-BB casting with the F65E-CC Romeo block
that’s completely different.
All five main
caps on the Windsors
are crossbolted, but they have dowels between main caps and block instead of the
jackscrews that were used for the Romeo blocks. All of the Windsor blocks have
the second hole on the driver’s side for the extended housing that moved the
filter to the back of the engine and they all have a threaded boss in the valley
that was used for the knock sensor or a bracket, but the hole may be either 8.0
mm or 12.0 mm, depending
on the year.
All of the F65E-BB blocks and some of the F75E
blocks had a 12.0 mm hole, but
some of the F75E castings had the smaller 8.0 mm hole. The parts book says that
most of the trucks had a knock sensor in 1997 and ’98, so they needed the bigger
hole, but some applications came without it and used a special stud and nut to
hold the water pipe that laid in the valley. We have seen a F75E block with PI
(Power Improved) heads on it with an 8.0 mm hole, so we know that the hole size was changed by 1999. However,
it could have been changed earlier, too, but our best guess is that the 1997s
and ’98s had the 12.0 mm hole and
the 1999s had the 8.0 mm
The bolt pattern
for the front cover is the same as it is on the late Romeo blocks, but the two
bolt holes just above the pan rail are 10 x 1.50 mm instead of 8 x 1.25 mm.
Most of the
Windsor blocks we have seen have the letter "W" cast somewhere on the block, on
the front, on the back, in the valley, and sometimes even on the sides, too, so
they’re usually pretty easy to spot.
have been two different castings used to make three different cranks for the
4.6L SOHC engines.
1991 – 1995
original crank used in the Romeo engines was an F1AE casting. It was a nodular
iron crank that had six, knife-edged counterweights and a six-hole flange for
the flywheel. It had a wide front counterweight that measured from .960˝ to
.980˝. There was a forged steel crank with eight counterweights (forging
#F2LE-AG) used in the DOHC engines, but it was never installed in any of the
SOHC motors, so don’t try to put it in one of them.
1996 – 1999
casting was used from 1996 through ’99. It looked like the original crank and it
still had a six-bolt flange, but the front counterweight measured from .920˝ to
.940˝ wide, so it was about .050˝ narrower than the earlier casting.
1997 – 1999
the Windsor motors came with the F65E crank. Some had
the six-bolt flange and some came with an eight-bolt flange, but there’s no sure
way to know which one was used for any given application, so it can be a real
problem for rebuilders.
It appears that most of the Windsors used the
eight-bolt crank, but there are definitely some of them out there with six-bolt
cranks, so check with the customer before selling an engine or a crank.
All of the
Windsor engines that have the six-bolt crank must be built with the F65E casting
that has the narrow front counterweight because there are two machined pads on
the back side of the front main that stick out far enough to hit the thick
counterweight on the F1AE crank.
All of the 4.6L rods are made of powdered metal and come with cracked caps, but
they’re not all the same. The rods used in the Romeo engines were designed for
press-fit pins while the ones in the Windsors were all bushed for full-floating
pins. (photo, top of page 36).
None of these connecting rods come with any
casting numbers, but you can sometimes make out the identification numbers that
were printed on the shank of the connecting rods; we have seen F1AE and F2AE
numbers, but there are probably several others that we haven’t noticed.
have been three different pistons used for the 4.6L through 1999, one for the
Romeos and two for the Windsors.
Romeo engines all used the same piston from 1991 through ’99. It had a small
(10.5 cc) dish and a 1.5 mm/1.5 mm/3.0 mm ring pack with a deep top ring groove
that was 3.825 mm/.151˝ deep. The pin was press-fit in the rod.
Windsor With NPI Heads
original piston for the Windsors
had a small (10.5 cc) dish and a 1.5 mm/1.5 mm/3.0 mm ring pack with a shallow
top ring groove that measured 3.325 mm/.131˝ deep. The Windsor rods were bushed,
so the pin was held in with circlips. This piston was used up through 1999 for
all of the engines that came with the “not power improved" (NPI) heads that had
the oval intake ports.
with PI Heads
Windsor pistons were changed in 1999 when the "power improved" (PI) heads with
the square intake ports and smaller heart-shaped chambers were introduced. The
size of the bowl was increased from 10.5 cc to 18.5 cc to make up for the
difference in the chamber size and still maintain the same compression ratio.
This piston still had the 1.5 mm/1.5 mm/3.0 mm ring pack with the shallow top
groove and circlips to hold the pin in place.
Ford has used several different heads on these engines. We have identified five
different ones for the Romeos and two for the Windsors through 1999. They all
seem to fit into the following pattern:
Romeo engine used the F1AE casting in 1991 and part of ’92. It appears that the
heads were changed at the same time the block was changed, so this head was
probably used through 11/1/91 on the Lincoln Town Cars and through 2/18/92 on
the rest of the Ford and Mercury cars.
It has two "ladder style" cam caps, nine bolt
holes for the rocker cover and it’s threaded for long reach spark plugs most of
the time. However, there are some F1AE castings that are threaded for the later
short reach plugs, so be sure to check the threads before using this casting.
Romeo (1992-’94 all, 1995 T-Bird/Cougar)
F2AE/F4AE head replaced the original Romeo head in mid-1992, but there are some
F1AE castings that are threaded for the short reach plugs, so they can be used
for these applications, too. There were two changes: 1) these castings had fewer
threads for the spark plugs; and 2) the pad on the front of the head for the
chain tensioner was 1.0 mm/.040˝ shorter than it was on the earlier heads.
Romeo Car (1995 Crown Victoria, Mercury Marquis, Lincoln Town Car and 1996–1997
The F5AE casting that had a revised combustion
chamber with a "swirl fin" (eyebrow) behind the intake valve was introduced in
some models in 1995. These heads also had an additional boss for a temp sensor
that was located under the front intake port on the driver’s side, but it wasn’t
always drilled because the cars didn’t use this sensor until 1998.
could be converted for use on the trucks by drilling and tapping the blind hole
and spot facing the boss for the sensor, but it takes a milling machine and a
fair amount of time to do it right, so it’s probably easier to catalog them
separately and use the castings that aren’t drilled on the cars that came
without the sensor.
Romeo Truck and 1998–1999 Romeo Car
castings that had the hole for the temp sensor drilled and tapped were used on
all the 1996-’99 trucks and the 1998-’99 cars. This sensor is installed in a
blind hole that doesn’t go to coolant because it is designed to sense the
temperature of the aluminum itself as a backup in case the coolant level is too
low to register on the coolant sensor.
1996–1999 Windsor "NPI"
F65E/F75 and F75E castings were all used on the Windsors from 1996 through ’99.
They had individual caps on each cam journal, 12 bolts instead of nine around
the perimeter of the head for the cam cover, and the four bolt holes on both
ends were 10 x 1.50 mm instead of 8 x 1.25 mm like they were on all the Romeo heads.
chambers on these heads had the "swirl-fin" behind the intake valves and they
had small, oval intake ports, so they’re called "not power improved" (NPI) heads
to differentiate them from the later design that’s known as the "power improved"
(PI) head. The "NPI" heads were used on all Windsors
up through 1998 and for some applications in 1999, so be sure to verify the
casting number before deciding which one to install on one of these later
Most of the
F65E/F75/F75E castings have a small, round, machined "restrictor" driven into
the head right under the wide cam cap, but we have seen a F65E with a machined
slot in the cap and no "restrictor" in the head. The hole in the heads that have
the slotted cap is too small for the "restrictor," so it’s not a problem as long
as you know what you’re looking for and you make sure you install the
"restrictor" in the heads that came with it.
have one problem with the "NPI" Windsor heads; the two blind holes that are used
for the pegs that hold the intake gasket in place during assembly are on the
bottom (toward the valley-side) of the intake ports most of the time. But, there
are some F75E castings that have the holes at the top side of the ports (near
the head). They were on the bottom on the F75E casting when it was used on the
4.6L from 1996-’99 and on the 5.4L in 1997.
They were on the
top of the F75E castings when they were used on the 5.4Ls in 1998 and ’99, and
they’re on the top of all the service replacement heads that are sold now.
Rebuilders need to send the matching intake set with a Windsor engine when they
sell one with "NPI" heads.
1999 Windsor "PI" Heads
"power improved" (PI) casting (XL3E) with the square intake ports was introduced
in 1999. It has bigger intake valves, different springs, and a small,
heart-shaped chamber that has a swirl-fin behind the intake valve. These heads
don’t have the "restrictor" that’s driven into the head, so the wide cap has the
small slot machined in the divider between the two sides.
The "PI" heads
weren’t installed on everything in 1999, and the parts books aren’t clear about
exactly where they were used, so there’s a lot of confusion about which
applications came with or without them.
In fact, no one
seems to know anything for sure, except that: 1) all the Mustangs had "PI" heads
in 1999; and 2) some of the trucks and Expeditions had them in 1999. Our best
guess is that all the Expeditions got them, along with some of the F250 pickups,
but they definitely weren’t used on all of the pickups in 1999, so be sure to
ask for the casting number before you sell an engine or a head.
though we’re not talking about anything beyond 1999, you should be aware that
there is a Romeo "PI" casting out there, too. The 1L2E casting has ladder caps,
small bolt holes in both ends and nine bolt holes for the cam cover along with
the square intake ports and the small heart-shaped chambers.
number is for a 2001 Explorer, so the "PI" head probably wasn’t used on Romeo
engines until then. But, it’s possible that there were some earlier applications
in spite of the casting number, so keep an eye out for them when you get a late
model Romeo core.
have been four different timing sets used on the modular motors, three on the
Romeos and one on the Windsors.
original timing set used on the Romeo motors had a roller chain, steel-backed,
plastic guides and the thin (about .960˝) tensioners along with right and left
tensioner arms. There were right and left tensioners with different oil passages
on the back side, but they were easy to tell apart because they had either an
"R" or "L" cast right on them.
1992-1/2 -1993 Romeo
second Romeo timing set still used the roller chain and it looked the same, but
it was slightly different because the mounting pad on the head was 1.0 mm/.040˝
shorter than it was on the earlier castings, so the tensioner was thicker and
there were right and left tensioner arms. There were three tensioners used on
these engines – a right one (marked “R”), a left one (marked “L”), and a
universal design with no marking on it.
third timing set for the Romeo motors had a link-style, silent timing chain
instead of the roller chain, so it had different sprockets, but everything else
stayed the same.
The tensioners and pivot arms on the Windsors are the
same ones that were used on the later Romeo engines, but the guides are made of
plastic with no steel backing and some of the mounting holes were moved, so
they’re completely different. All the Windsors had the link-type, silent timing
chain and gears.
for the 4.6L engines can be pretty confusing. They’re all hollow designs with
pressed-on lobes, but that’s where the similarity ends, because there are right
and left cams that came with and without the gears and there are several
different profiles to consider.
The cam chart
(below) is our best take on it with the help of Milt Olson from Engine Power
Components. We’ve also seen three other cams that we haven’t been able to
identify by application (F1AE-6250-BD/F65E-6250-AA/F1AE-6A274-BD), so we aren’t
using them in anything at this point. The rest of them appear to be
interchangeable as shown on the chart, but that’s just an opinion, so let your
conscience be your guide when consolidating cams for these engines.
have been several front covers used on these engines, depending on both the year
and the application. The chart (below) provides a good overview, but there are a
few things worth noting:
F1AE/F2AE front covers had 15 small holes (8.0 mm) around the perimeter and no bosses for the tensioner.
F3AE/F5AE covers still had the small (8.0 mm) holes, but they also had six cast bosses on the passenger side
that were used to mount the tensioner and idler for the serpentine belt.
Romeo and Windsor
Car (except 1999 Mustang)
front cover for the car was changed in 1996 when the Windsor motor was
introduced. The six bosses for the tensioner were the same, but the bolt hole by
the water pump was moved up about .250˝ and 10 of the holes were opened up to
10.0 mm to accommodate the larger bolts that were used for some of the
holes on the Windsors.
F6AE/F7AE/F7ZE/F8ZE castings were used on all the cars from 1996 through ’99,
except for the Mustang that had its own unique front cover in 1999.
1996 – ’99
Truck, Van and Expedition (except ’99 Econoline)
the trucks, Expeditions and vans (except the 1999 Econoline) shared a common
front cover. The F65E casting had 10 large 10.0 mm bolt holes and five, small 8.0 mm holes along with six bolt bosses for the tensioner. However, the
bosses for the tensioner were arranged in a different pattern that was unique to
the trucks, so the car and truck covers can’t be interchanged.
front cover on the 1999 Mustang was an XR3E casting. It had four bosses for the
tensioner and a machined pad for the idler further down on the passenger side of
Econoline had its own special 2L3E front cover. It looked the same as the
earlier F65E truck casting, but the 30° timing pointer was no longer cast on the
That pretty well covers all the major components
for the 4.6L Ford engines, but that’s not all there is to the story. There are a
few other things every professional rebuilder should know about these engines
before starting to rebuild them.
Ford recommends torque-plate honing all the 4.6L
Ford recommends replacing the head bolts every
time the heads are removed from the engine.
There is no way to know whether a Windsor motor
came with a six-bolt or eight-bolt crank until it’s out of the vehicle, no
matter what the customer says, so make him take it out and look at it before
you ship him an engine.
These blocks can’t be bored more than +.020˝
(oversize) because the fire ring in the head gasket is too small to
accommodate a larger bore.
Don’t mix up the ring sets. Putting a deep top
ring in a shallow groove or vice versa is a sure-fire comeback.
The 4.6L Ford was the first engine to use a
multi-layered steel head gasket. It required a super-slick finish on the heads
and block. We have been successful rebuilding this engine by maintaining a
surface finish around 40 Ra on the block and 20 Ra on the heads. Don’t take
chances with a finish that’s too rough. The geometry of the head and block
must be straight and true as well in order to achieve proper sealing.
You can’t recondition the rods by cutting the caps
because of the cracked cap, but there are oversize rod bearings available in
the aftermarket that work fine.
We have seen several of the left hand cam
sprockets for the Romeo motors that have the tab that indexes in the keyway
completely sheared off. Check both the cams and the gears carefully before
There are reports that there were some oversize
rods in new engines, so double-check them, especially if you’re not using
oversize rod bearings.
These engines appear to be very prone to
detonation. We have seen several pistons with rod bearings that have been
pounded to death from abnormal combustion. Some of the Romeo engines that are
used in police cars and limos appear to have serious detonation problems, so
watch out for comebacks with these applications.
That’s what we know about the 4.6L Ford. Start
here and build on this information with your own experience and you’ll be ahead
of the game. There are thousands of these engines out there and they’re not all
going the miles, so there should be plenty of opportunities for everyone in the
industry to build a bunch of them.
Note: This article would not have been possible without the help of many other
people in the industry who shared their knowledge and experience. A special
thanks to Roy Berndt at the Production Engine Remanufacturers Association (PERA),
Milt Olson from Engine Power Components and the people at Mahle for all their
is vice president of Grooms Engines, Parts, Machining, Inc., a production engine
remanufacturer in Nashville, TN.
Injector Flow Rate (lb/hr)
Engine HP(1) x BSFC(2)
Number of Injectors x Injector duty cycle(3)
Injector Flow Rate
Engine HP(1) x BSFC(2)
Number of Injectors x Injector duty cycle(3)
injectors max HP (lb/hr)* =
rate x Number of injectors x 0.8
injectors max HP (cc/min)* =
rate x Number of injectors x 0.8
BSFC x 10.5
Injector flow rate conversions:
|Fuel injectors flow
Fuel injector flow
|Fuel injector flow
Fuel injectors flow
(lb/hr) x 10.5
03-04 Cobra (Terminator)
- steel crank
- Manley H-beam rods
- forged dished pistons (GT engines have flat top
XW7E cast iron
block (all other Cobra/Mach 1 blocks are aluminum)
- 8 bolt crank
- stock cam specs – 184/196 duration at .050,
.394/.394 lift, 114 lobe separation)
03-04 Cobra head
The head tick issue
is a common problem on 03-04 Cobras. From the driver side of the engine
you can here a ticking noise that sounds like a lifter tick or exhaust leak,
especially after the car is warmed up. The tick is the valve ticking
inside the valve guide which has become worn from heat due to poor coolant flow
in that area of the driver side cylinder head. These heads do not have
bronze valve guides either which doesn’t help this problem at all. This
ticking noise is more of a nuisance than anything and doesn’t cause any
significant immediate damage. There are revised factory heads that fix
this ticking problem and there is also a few companies that make cooling
modifications that can help prevent this problem from occurring. The
revised factory heads that are updated versions and have improved cooling
passages which eliminate the heat issues which cause this tick issue.
updated heads have additional spark plug threads (9 versus the original 4
threads) and improved cooling around the exhaust valve guides and better coolant
flow over all. The part numbers for these heads are 2C5Z-6049-BAB for the left
(driver) head and 2C5Z-6049-CAB for the right (passenger) side. Some oil
filters have been known to cause a ticking noise also so if you experience a
ticking, verify where it is coming from before your get too excited.
Cobra Engine Specs:
Displacement 4.6L (4V) (281 CID)
Number of cylinders 8
Bore 90.2 mm (3.55 in)
Stroke 90.0 mm (3.54 in)
Firing order 1-3-7-2-6-5-4-8
Oil pressure 138-310 kPa
Oil capacity 6 ± 0.25
Compression ratio 8.5:1
Supercharger displacement – 112 cubic inches
– 390hp @ 6000 rpm
390 @ 3500 rpm
*Cylinder Head and Valve Train*
Cylinder head gasket surface flatness 0.10 mm (0.004 inch) max. overall
Combustion chamber volume 52.6 ± 0.5 cm
Valve arrangement (front to rear)
Intake (left hand): S-P-S-P-S-P-S-P (P=Primary –
Intake (right hand): P-S-P-S-P-S-P-S
Exhaust (left hand): E-E-E-E-E-E-E-E (Exhaust)
Exhaust (right hand): E-E-E-E-E-E-E-E
Valve guide bore diameter 7.015-7.044 mm (0.2762-0.2773 in)
Valve stem diameter—intake 6.975-6.995 mm (0.2754-0.2746 inch)
Valve stem diameter—exhaust 6.949-6.970 mm (0.2744-0.2736 inch)
Valve stem-to-guide clearance—intake 0.020-0.069 mm (0.00078-0.00272 inch)
Valve stem-to-guide clearance—exhaust 0.046-0.094 mm (0.0018-0.0037 in)
Valve head diameter—intake 37 mm (1.46 inch)
Valve head diameter—exhaust 30 mm (1.18 inch)
Valve face runout 0.05 mm (0.002 in)
Valve face angle 45.5 degrees
Valve seat width—intake 1.8-2.2 mm (0.071-0.086 inch)
Valve seat width—exhaust 1.8-2.2 mm (0.071-0.086 inch)
Valve seat runout 0.05 mm (0.002 inch)
Valve seat angle 45 degrees
Valve spring free length—intake 42.16 mm (1.6598 inch)
Valve spring free length—exhaust 42.16 mm (1.6598 inch)
Valve spring squareness 2 degrees
Valve spring compression pressure—intake 711.47 N @ 26.19 mm (159.9 lb-ft @
Valve spring compression pressure—exhaust 711.47 N @ 26.19 mm (159.9 lb-ft @
Valve spring installed height 36.14 mm (1.4228 in)
Valve spring installed pressure—intake 289.1 N @ 36.14 mm (64.99 lb-ft @ 1.4228
Valve spring installed pressure—exhaust 289.1 N @ 36.14 mm (64.99 lb-ft @ 1.4228
Roller follower ratio 1.8:1
Hydraulic Lash Adjuster
Diameter 16.000-15.988 mm (0.6299-0.6294 inch)
Clearance-to-bore 0.018-0.069 mm (0.000709-0.002717 inch)
Service limit 0.016 mm (1.0006299 inch)
Hydraulic leakdown rate
Collapsed lash adjuster gap 0.80-1.20 mm (0.0315-0.0472 inch)
Theoretical valve lift @ 0 lash—intake (primary and secondary) 10.0 mm (0.3937
Theoretical valve lift @ 0 lash—exhaust 10.0 mm (0.3937 inch)
Lobe lift 5.54 mm (0.218 in)
Allowable lobe lift loss 0.130 mm (0.0051 in)
Journal diameter 26.962-26.936 mm (1.0615-1.0605 inch)
Camshaft journal bore inside diameter 27.012-26.987 mm (1.0635-1.0625 in)
Camshaft journal-to bearing clearance 0.025-0.076 mm (0.00098-0.002992 inch)
Runout 0.025 mm (0.0010 in)
End play 0.025-0.165 mm (0.00098-0.00649 inch)
Cylinder bore diameter 90.2-90.239 mm
Cylinder bore maximum taper 0.016 mm
Cylinder bore maximum out-of-round 0.016 mm
Main bearing bore diameter 72.402-72.422 mm
Head gasket surface flatness 0.15 mm (0.006 in) max. overall
Main bearing journal diameter 67.493 mm
Main bearing journal maximum taper 0.05 mm
Main bearing journal maximum out-of round 0.05 mm
Main bearing journal-to-cylinder block clearance 0.023-0.055 mm
Connecting rod journal diameter 52.983-53.003 mm
Connecting rod journal maximum taper 0.004 mm (0.0002 in)
Connecting rod journal maximum out-of-round 0.004 mm (0.0002 in)
Crankshaft maximum end play 0.130-0.301 mm
Thrust bearing journal diameter 67.493 mm
Thrust bearing journal maximum out-of round 0.05 mm
Thrust bearing journal maximum taper 0.05 mm
Thrust bearing journal length 17.725-17.775 mm
Piston and Connecting Rod
Piston diameter 90.180-90.191 mm
Piston-to-cylinder bore clearance -0.010/+0.026 mm
Piston ring end gap — compression (top) 0.30 mm
Piston ring end gap — compression (bottom) 0.50 mm
Piston ring end gap — compression (oil ring) 0.65 mm
Piston ring groove width — compression (top) 1.53-1.549 mm
Piston ring groove width — compression (bottom) 1.519-1.539 mm
Piston ring groove width — oil ring 3.031-3.055 mm
Piston ring width — compression (top) 1.47-1.49 mm
Piston ring width — compression (bottom) 1.47-1.49 mm
Piston ring width — oil ring 2.854-2.984 mm
Piston ring-to groove clearance — compression (top) 0.04-0.079 mm
Piston ring-to groove clearance — compression (bottom) 0.029-0.069 mm
Piston ring-to groove clearance — oil ring 0.047-0.201 mm
Piston pin bore diameter 22.0042-21.998 mm
Piston pin diameter 21.991-29.994 mm
Piston pin length 61.60-62.03 mm
Piston pin-to-piston fit 0.0058-0.0132 mm
Connecting rod-to-pin clearance 0.018-0.033 mm
Connecting rod pin bore diameter 22.012-22.024 mm
Connecting rod length 150.7 mm
Connecting rod maximum allowed bend 0.038 mm per 25 mm
Connecting rod maximum allowed twist 0.050 mm per 25 mm
Connecting rod bearing bore diameter 56.866-56.886 mm
Connecting rod bearing-to-crankshaft clearance 0.027-0.069 mm
Connecting rod side clearance 0.15-0.45 mm
Accessory serpentine belt
- 6 rib. 96".
- Stock belt is 75.1". Gates stock number is K080751. Gatorback stock number