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> Flex plates should be interchangeable with other Small Block Fords.

No. You'll find there are 157 teeth and 164 teeth versions, along with
28.2 oz-in and 50 oz-in flex plates (also neutral balance if you include
the 300 truck six which shares the same bolt pattern). There were small
and large C4 bell housings. The small used the 157 teeth flex plates
while the large used 164. There was also a smaller C4 used in the
Pintos and Mustang II's (I've seen 141, 143 and 148 teeth claimed at
various times but have never come across any of those). Also the 157
teeth flex-plates have a 10.5" converter bolt pattern, while the 164 tooth
flex-plate is 11 7/16".

351C's came with 28.2 oz-in 164 teeth flex plates. If you try to use
a stock size starter with a 157 teeth, it will not clear the oil pan
lip unless you roll it back. I've done that before but it's better to
use a mini-starter. The small bellhousings are nice as they have more
clearance for headers.

Google Moneymaker Racing (Alex Denysenko) and he can set you up with
the right flex plate for you application. Below I've added a few C4
notes from the write up I did after I did a C4-to-AOD swap in my
mom's Mustang convertible.

Dan Jones

Balance Factor Information

1981-and-up 5.0L - 50.0 oz-in
Pre-1981 289/302 - 28.2 oz-in
351W and 351C-400 - 28.2 oz-in

C4 and AOD Dimensions

Overall Length (bellhousing to tailshaft housing end, flat-to-flat):
AOD - 30 3/4"
C4 - 30 1/4"

"Engine Swapping Tips and Techniques" lists C4 length as 27 3/4" (C6 length
28 1/2" or 28 3/4"). I may have measured to the end of the output shaft,
not to the end of the tailshaft housing.

Distance from Bellhousing to Insulator Mount (flat to mounting hole centerline):
AOD - 21 3/4"
C4 - 19 3/4"

Torque Converter Stud Spacing (centerline-to-centerline)
AOD/C4/164 teeth flexplate - 8 1/4" between closest studs, 11 7/16" between
farthest studs (stud pattern diameter)
C4/157 teeth flexplate - 7 3/4" between closest studs, 10 5/8" between
farthest studs (stud pattern diameter)

Transmission Lengths from "The E4OD", Ford High Performance, April 1995

Trans Bellhousing Overall Length
Face to Trans From Bellhousing
Mount Length To Tailshaft End

C4 20 1/4" 30 1/2"
C6 22 1/2" 33 1/2"
AOD 22 1/4" 30 3/4"
E4OD 29 3/8" 37 1/2"

Torque Converter Snout Diameter (from early SVO catalog)
289, 302, 351W/C/M, 400, 429/460 - 1.375"
FE series and early '68 Lincoln 460's - 1.848"

Flexplate Diameters
164 teeth - 14 3/16" (13" converter)
157 teeth - 13 1/4" (11" converter)
141 teeth - ?

Mustang II used 148 teeth flywheels and 141 teeth flexplates.

C4 Variations

C4 detachable bellhousing, case, and tailshaft housing.

Large bellhousing - smooth flair case, twin bolt circles (case to housing,
outer secures bellhousing to trans case, inner secures oil pump to case),
3 locating tabs, 14 3/16" flexplate, 13" converter, no dipstick hole in
main case (dipstick goes into right front corner of pan), used in small-block
powered large cars and light trucks.

Small bellhousing - step case, single seven bolt circle (case to housing),
13 1/4" flex plate, 11" torque converter, dipstick hole in case (seals with
an O-ring), five bolt ('64 1/2 and early '65 Mustangs, etc.) and six bolt
versions, used in small and medium small-block powered cars.

Trans-Dapt supposedly makes adapters for six bolt blocks to five bolt
transmissions (need to check on details).

Top bellhousing bolt holes are 5 1/8" apart.

"C" intermediate servo (289 hipo applications) is largest but rare.
"H" servo is next largest, used on 302 4V engines from 1968.
"A" servo is typical stock unit.

Pinto governor allows highest rpm shifts, p/n D7ZZ-7C063-C.

C5 pan interchanges with C4 and is deeper.

There was a revision in mid '70's to nine mounting bolts for the valve body,
previously used 8 bolts.

Main cases and bellhousings for large and small versions are not
interchangeable. 5 and 6 bolt small bellhousings are interchangeable between
each other (on the case side).

Entire 6 bolt (small or large bellhousings) transmissions, except for
dipstick locations, are interchangeable in many cars (some smaller cars
require the small bellhousing variant).

C5 bellhousing looks similar, but has a completely round hole in the front
pump area and is not interchangeable with C4 bellhousing.

Standard Tailshaft - 13 1/8" long, most applications.
Short Tailshaft - 6 5/8" long, some pickups and vans.

Input Shaft Spline Count (8 cylinder and some 6 cylinder applications)
'70 and later - 26 splines
pre-'70 - 24 splines

Note: Some 1970 input shafts have 26 splines on both ends ('71 and later have
24 splines on one end and 26 on the other), making them the most desirable
for drag racing applications.

Need to add C4 valve body variations (green-dot, cruise-o-matic, etc.) and
AOD shift sequence

Four and six cylinder versions are light duty (fewer clutch plates).

Some C4's (late '60s, early 70's Mavericks? need to check details) had
full-manual valve bodies.

Major C6 variations

C6 integral bellhousing (case and bellhousing are one piece) with tailshaft

FE big blocks - round bellhousing opening with top bolts 6" apart,
often have stiffening ribs on top of case/bellhousing

302/351W/351C - bellhousing opening is squared off on top, case opening
is 16 3/4" tall, top bolts are 5 1/8" apart, no ribs

351M/400/429/460 - bellhousing opening is squared off on top, case opening
is 17 3/4" tall, top bolts are 7 3/4" apart, has ribs

Transmission Weights

AOD (without converter or fluid) - 150 lbs
AOD stock torque converter - 34 lbs
C4 (without converter or fluid) - 110 lbs
C4 torque converter - ? lbs
C6 (without converter or fluid) - 140 lbs
C6 torque converter - 30 lbs small block, 31 lbs big block
FMX (without torque converter, unknown fluid level) - 160 lbs
FMX torque converter - 32 lbs
Ford-o-Matic (pre-FMX), cast iron case - 228 lbs


- AOD and C4 weights are as measured by me using a standard bathroom scale.
- FMX and C6 torque converter weights provided by Steve Grossen (also used
bathroom scale).
- Ford-o-Matic weight is an assembly line weight provided by my Dad.
- C6 weight is from "Engine Swapping Tips and Techniques" which also lists
the C4 at 109 lbs.
Many Thanks Corey and Dan as usual a wealth of information.

Actually the application is for friend who has a 1965 mustang with a C4 and a 289 ... I sold him my 351C ... so I;m trying to prepare for this swap in one day ...

If I read correctly and my inspection of the car its not an early 64 -65 motor and trans.

The C4 installed has 6 bolt bell housing.

It appears to be a smaller C4 bell housing 157 teeth - 13 1/4" (11" converter).

Would I be correct in saying the 28oz flywheel out of a 289 will be OK 28oz balance for the 351C ? If that the case then if i use the 289 flywheel the trans and converter should bolt right up?

> Would I be correct in saying the 28oz flywheel out of a 289 will be OK
> 28oz balance for the 351C ? If that the case then if i use the 289 flywheel
> the trans and converter should bolt right up?

Yes. If it is a small case with 157 teeth flexplate, the 289 starter won't
fit unless you roll the oil pan lip or switch to a mini-starter. You'll
also need the corresponding block plate (the 351C block plate will have
the starter hole position for the 164 teeth flexplate). Note 289's had
both 157 and 164 teeth flexplates, depending upon what chassis the engine
was originally installed in.

If the engine is a later 302, the flexplate may have a different balance
factor (depends upon the year).

Dan Jones

Called Alex and he is very helpful also .. the motor and trans are 65 289 w/ C4 ... so using everything ..flywheel, block plate and C4 should bolt up to the 351C. Only thing i find in the reading is the headers / exh manifolds on the steering box...but Alex makes conversion headers ... so i guess i will report back sunday and update you if all went well.

Thanks again

> Actually the application is for friend who has a 1965 mustang with a C4 and a 289
> I sold him my 351C ... so I;m trying to prepare for this swap in one day ...

I swapped a 351C into my 1966 Mustang fastback.

> C4 should bolt up to the 351C.

If he wants to stick with an automatic, he should seriously consider an AOD.
I have a very detailed write up I did on swapping in an AOD if he's interested.
The AOD has overdrive and a lock up torque converter so you can a higher stall
speed and still have it cruise without slippage. I did the 351C/C4 swap and
the 289 C4 torque convertor stall speed was too low (would either stall or lurch
when putting into gear). I installed a higher stall converter but the slippage
and without overdrive the thing would turn high RPM just keeping up with highway
traffic. I dumped the C4 and installed a Tremec TKO 5 speed. So much better.
I've also done AOD conversions in early Mustangs and they work great too.

> Only thing i find in the reading is the headers / exh manifolds on the steering
> box...

You can't install a 351C in a 1965 Mustang with exhaust manifolds at all.
The shock towers are far too narrow. The headers I used were from Tubular
Automotive and have tubes from on bank that cross under the oil pan to the
opposite side collector. The 4V versions have too large a collector but it's
a slip fit so a smaller diameter can be fitted. The '65 uses a one piece
steering shaft. Once the engine is in place, you have to remove the engine
to R&R the steering box. I recommend installing a 2 piece shaft and steering
box from a '68 Mustang (IIRC '67 was a transition year so later ones will also
have a 2 piece shaft with safety coupler). At the very least, have your steering
box rebuilt.

> Alex makes conversion headers

I'm not sure what headers Alex carries but I've there are ones that don't
go under the pan. Either way, the headers have a very sharp turn at the
exhaust port.

Many years ago, I put together some swap notes for '65 and '66 Mustangs.
I've attached them below but be aware that some of the information may be
outdated by now.

Dan Jones

1964-1966 Mustang Engine Swaps FYI

Below, I've put together some information relative to 351W and 351C engine
swaps into 64-66 Mustangs. Since the shock towers of these Mustangs are
quite narrow, engine swap choices are restricted to the mid-sized 351's.
You can forget about big blocks, modular motors, or even a 351M/400, unless
you are willing to do major surgery (i.e. shock tower removal). Of the Ford
351's, the 351W is the most popular. Less popular, but still possible with
special headers and maybe little tower massaging, are 351C swaps.

Essentially a taller deck version of the 289/302, the 351W is the most
straightforward of the mid-size blocks to swap in. The 351W is taller and
wider, but fits within the general V envelope of the 289/302 engine. The
351W (and 351C) share the 289/302 motor mounts and bellhousing bolt patterns
(64-65 5 bolt 260/289 blocks excluded). Unfortunately, there isn't enough
clearance between the heads and the shock towers to fit the stock 351W
exhaust manifolds. The shock towers could be notched to provide the
necessary clearance, but the usual approach is to replace the cast iron
exhaust manifolds with a set of steel tubing headers, preferably ones made
specifically for the swap.

In some cases, the companies listed below have a specific swap header for
64-66 Mustangs with 351W's. In other cases, they show a generic header for
64-73 Mustangs with 289/302/351W engines. Your best bet is to stick with the
specific swap headers. There's an outside chance the generic headers will
fit but most likely they will require mods to the shock towers and/or header

A long while ago, I did some checking into 64-66 Mustang 351W swap headers
for one of the list members who suffered sticker shock over the JBA swap
header price ($699 for his case). I was suprised to see so few places making
headers 64-66 Mustang 351W swap headers. This is a fairly common swap, so I
expected to see a wide variety of vendors supplying these headers. I actually
ran across more places with Pinto 351W swap headers. Hedmann has recently
stepped in to fill the void with 351W swap headers but make sure they are
compatible with your heads. Some aftermaket Windsor heads have raised exhaust
ports and may not quite fit.

1. Mustangs Unlimited (from their 1995 catalog)
800-243-7278 order
203-647-1965 tech and local

MU carries a specific 64-66 Mustang 351W header (1 1/2" primaries
with 3 1/2" collectors). Part number is ES9.

They also list the JBA 1606 header for $699.95 (1 3/4" primaries,
3 1/2" collector) but note that it will not fit power steering cars
and the equalizer bar from a 1967 standard 289 engine must be used.

Their catalog claims that power steering brackets are required for
any 64-70 Mustang using any style header and power steering.

Mustangs Unlimited also lists 64-66 Mustang 351C swap headers in
their 1995 catalog. For the 2V heads, they have part number ES7
(1 3/4" primaries with 3 1/2" collectors). For the 4V heads, they
have part number ES7A (1 7/8" primaries with 3 1/2" collectors).

2. Sacramento Mustangs
order 800-442-8333
info 916 334-0190

Note: This info is from an old (1989) performance catalog supplement.

They list a custom header for 64-66 Mustang, Comet, Falcon, and 70-76
Maverick and Comet applications. They might be sourcing the headers
from Total Performance (or their supplier) since they show several
other swap headers that TP sell (like the 64-66 351C headers).

They also have a generic listing for 64-70 289/302/351W Tri-Y headers
and list a power steering adapter.

3. Total Performance
44050 N. Groesbeck Hwy.
Clinton Township, MI 48036-1108
313-468-7434 fax

Note: This is from a 1989 price sheet.

Part number 8009 is listed as fitting 60-66 Mustang, Comet, Falcon,
70-78 Maverick and Comet applications with 351W's, 1 1/2' primaries.
Also list 64-66 351C Mustang swap headers in 2V or 4V flange.

4. Tubular Automotive
PO Box 279
248 Weymouth St
Rockland MA 02370

Lots of swap headers for Fords, including 351C into '65-'66.
Darkhorse Performance carries Tubular Automotive headers.

Darkhorse Performance
16617 SE 134th
Renton, WA 98059
425-277-3893 fax

5. Pro Mustang Performance
2070 Del Amo Blvd
Torrance, CA 90501

Custom 351C into '65-'66 Mustang swap headers.

6. Ford Powertrain Applications
Phone/Fax: (253) 848-9503
9am - 6pm Pacific Time - Monday - Friday
Email -

351C and 351W headers into '65-'66 Mustangs.

7. Hedman Hedders
16410 Manning Way
Cerritos, CA 90703
310-921-7515 fax

Hedman has recently introduced two sets of 351W headers specifically
designed for swaps into 64-73 Mustangs:

P/N 88660 - Full Length - 1 5/8" primaries with 3" collectors
P/N 88650 - shorty

Note: a couple of guys have had real trouble swaping in aftermaket headed
(Dart, TW) 351W's. Here's what one said:

* Unless you are a masochist, DO NOT put Dart heads on your early Mustang,
particularly the '65-66. They are great heads BUT the plugs are seriously
relocated, enough for you to go to "custom headers" which are more aggravating
than I'd care to discuss. Fox Mustang owners will gladly take your Darts if
you're reading this a little late in the game; they can use 'em all day long.
I recommend Edelbrock Performer RPMs or GT-40 Aluminums for early car folks.
They go right on there, pretty as you please.

I did talk to Bill Mitchell, maker of the Dart heads, recently, and he
admitted that the relocated plugs were giving people problems. He said my
circa 1995 heads were "old" and that the new batch of heads has the stock
locations for the plugs again. So, get the *new* Darts.

One list member was able to make a set of generic Hedman Hedders work in his
'66 fastback ('69 351W with C4). He notched the shock towers in 3 places and
modified the end of the headers where they exit. The job was time consuming
as it involved several iterations of dropping the engine in (without tranny),
putting the headers on, marking where they touched the shock towers, pulling
the engine out, heating up the area with a torch, and notching it in with a
round buck and a hammer. He reported the end result was very professional

A member in the local (St. Louis) Ford club had good luck with the 351W swap
headers from Total Performance (much better than my own experience with TP's
351C swap headers). His swap consisted of a 351W with T5 manual transmission
and air conditioning into a 1966 Shelby GT350.

Hooker may also make a header that will fit the early Mustang chassis. Here's
what one individual (David Cole) on the web had to say. "On the headers: Hooker
Super Comps. Part #6208. These are 1 3/4" headers with 32" tubes. I have well
over 400 rwhp in my 383-W and they are plenty big enough. These are engine swap
headers to let you put the 351-W in an early Mustang. They fit 65-70 Mustangs.
I have them in my 69, but they are designed to fit the earlier cars also. Before
I bought them I called Hooker. They told me that these headers were designed to
be able to fit a 65 Mustang with a 351W and C-6. Anything else is cake. I have
seen them installed in a 65 and a 66 and they fit well. True, plugs are a little
tight to get to, but it is workable. These headers are available mailorder for
around $360. Hedman also makes a set. I had some but refused to install them due
to poor quality."

In all cases, you'll need to verify fit for your specific combination of
transmission (automatic or manual), power steering, air conditioning, etc.

In most cases, early Mustangs with power steering will need to have the power
steering slave cylinder relocated using a swap bracket. One list member
reported the bracket is inadequate to take the load from the power steering
system. His fix was to weld the bracket to the frame with a pair of 1/4"
plate gussets behind it.

Many times headers for Fords are listed as being incompatible with automatic
transmissions but often this applies only to the large bellhousing C4, C6,
and FMX. In those cases, switching to a small bellhousing C4 (and matching
blockplate) and a 157 tooth flywheel (28.2 oz-in balance factor) will provide
the required clearance. When doing this, you may need to roll the lip of the
oil pan back a bit to get proper starter placement. With a 64-66 Mustang,
the C4 (or an AOD if you want overdrive) is definitely the way to go if you
want an automatic transmission. The C6 is much larger and will require
transmission tunnel work to fit.

You may also want to consider switching to the small diameter, late model,
permanent magnet starter that came on some Lincolns and later Mustangs. Once
your headers are in place, you may find it impossible to remove or install
the starter (I did), without removing the headers or disassembling part of
the suspension. The lightweight starter is much smaller and slipped right
through the header tubes. SVO sells them new with a wiring harness and
instructions. These can be had for less than $150. My favorite approach
is to find a core and get it rebuilt with a lifetime warranty. If you go
this route, remember these starters are wired differently. I should have a
copy of the wiring diagram (it's very simple), if you need it. switch to 164 tooth flywheel during Tremec the SVO mini starter no longer
fits. Manual 351C's and Boss 302's use 164 teeth flywheels that have a
different ring gear location than the 157 teeth flywheels and flexplates
ad the 164 teeth flexplates. There are several aftermarket mini starters
that will work. The least expensive was one mentioned on the Pantera email

Aftermarket bellhousings and heads, suspension modifications, steering
modifications (like the Shelby quick-steer kit with longer idler and pitman
arms) can complicate matters as well. In many cases, oil filter relocation
(using a 90 degree elbow or remote filter), will be required or will make
things easier. My swap headers fit with only a little clearancing on my
Lakewood scattershield.

Another tip is to install a torque strap to limit engine rock under
acceleration. This can keep the headers and air filter case from making
contact with inner fenders or hood. I also suggest you wait until you've
made a trial fit and any needed modifications before you have any sort of
coating applied to the headers.

Over the years, the shock towers on early Mustangs tend to sag towards each
other. This can complicate a 351W or 351C engine swap. The proper dimension
for 64-70 Mustangs is 40" from inner fender to inner fender (at the Monte
Carlo bar mounting points). You may need to use a port-a-power to spread
them apart. Once you have the engine in, install a Monte Carlo bar to keep
the shock towers from flexing under load and causing clearance problems.

Hood clearance will be tight. Early '65 style motor mounts, with the big
stud pointing straight down, allow the engine to sit lower. Late '65 and
'66 with the bolt that passes horizontally through the mount, places the
engine higher so hood clearance is tighter but ground clearance is lower.
Low profile intake manifolds and air cleaners are generally required if you
don't use a hood scoop. Remember to leave enough clearance to account for
the engine rocking in its mounts. I originally used an Edelbrock F-351
intake and 14"x3" drop base K&N air cleaner on my 351C and it had room to
spare. For taller intakes, a remote air filter may solve the clearance
issues. A local club member with the 351W in his Shelby GT350 used both
Performer and Torker II intakes with a low profile Mopar open element air

In many cases, sparkplug access can be tight, so some general sparkplug tips
are in order. The first tip is obvious but easy to overlook. Many sparkplug
sockets have flats on them so they can be used with an open end wrench,
instead of a ratchet handle. Sometimes the wrench will need to be bent to get
the proper clearance. The second tip is handy when it's difficult to get a
socket on the plug. Cut a U-shaped opening into the side of the socket. This
opening can be aligned with the plug to gain clearance. Since the opening
will weaken the socket, try to remove the minimum amount required for
clearance. In some cases, you can also trim the overall length of the socket
for additional clearance. Eastwood also makes a telescoping spark plug
socket that might fit where others don't. Also, Accel makes plugs that are
approximately 3/8" shorter than standard plugs. If you still can't get a
socket on, try heating and bending a box-end wrench to fit. The final tip can
help get the plug started in tight spaces. Push a piece of rubber hose over
the end of the sparkplug and use it to position the the sparkplug at the hole.
Simply spin the hose to start the plug.

Specially modified tools can also come in handy elsewhere. I bent and
trimmed some box wrenches to make it easier to do home alignments.

If you're still running points, you may want to switch over to a high energy
electronic ignition to extend sparkplug life. However, I'd stay away from
platinum plugs. Under the right circumstances, platinum plugs can have
remarkably long service lives, but they seem to be susceptible to rich
mixtures and can foul easily.

The 351W is approximately 65 to 75 lbs heavier than a comparable 289/302.
A 351C is another 25 lbs more (see the engine weights and dimensions chart
below). You can compensate for the increased front end weight by installing
stiffer and/or taller springs in front. You may also want to increase rear
spring rate or add a traction device to handle the increased torque. See
the Early Mustang Suspension FYI for details.

Of course, you can also lighten the load by using aluminum heads, an aluminum
water pump, a lightweight starter, tube headers, a fiberglass hood, relocated
battery or by deleting heavy accessories like air conditioning and power
steering. On the 351C in my '66 fastback, I have no power accessories, an
aluminum intake, tube headers, a lightweight starter, and a relocated battery
(trunk mounted). I expect my front end weight isn't that much different than
a '66 289 Mustang with cast iron intake and exhaust manifolds and maybe a few

The magazines have featured 351W swaps a number of times:

1. "Windsor of Change", Mustang and Fords, September 1993.

This article details a 351W swap performed by Dyno Don Nicholson into a
friend's 1966 GT fastback. JBA swap headers were used. The shock towers
on this car had sagged and had to be port-a-powered apart. The 351W was
dyno tested with both Torker II and Performer intake manifolds. The Torker
II, with a one inch spacer, made the most power but would not fit under the
hood so the Performer intake was used instead. The car was fitted with power
steering and a C4 automatic, both of which are not supposed to work with the
JBA headers. Power steering bracket lengthening was required. A four core
radiator was used.

2. "Old Favorite", Super Ford, November 1991.

This article covers a 351W swap into a 1966 fastback using JBA headers and
a T-5 transmission.

3. "'Stang With Sting", Hot Rod, date unknown.

Another 1966 fastback with 351W, this time with Doug Nash 5 speed tranny.

The 351W swap is, for the most part, straightforward. The 351C swap, on
the other hand, is more involved. The Cleveland heads are wider than their
Windsor counterparts, making the shock tower clearance problem more
difficult. Special swap headers or shock tower modifications are required.
Sparkplug access will be tight. The swap headers will have a 90 degree
bend coming out of the port so exhaust flow will be hurt some. On the plus
side, the 351C has a lower deck height, so hood clearance will be a bit
better. The 351C also has better flowing factory heads and strong
crank, rods, and main caps. It will take more work than a 351W swap, but
the results can be impressive.

Three list members have voiced their experience with 351C into 64-66 Mustang
swaps. Here's what Darius Rudis had to say:

"My best friend stuffed a 351C (yes Cleveland 4V) into his 1966 coupe.
This I would say physically fits, but not really. By the time the shock
towers were sludge hammered out it looked pretty sad. The car is fast as
hell, and a real sleeper. The hardest part of driving it is not switching
lanes as you shift the toploader cause of all the torque and tire spin it
is difficult to drive hard. The 351W, I am not sure how hard it would be
to stick that in, but I know it is a lot less difficult than the 351C.
Plus there are companies who sell headers for the swap."

Here's how Dave Williams responded:

"-> My best friend stuffed a 351C (yes Cleveland 4V) into his 1966 coupe.
-> This I would say physically fits, but not really. By the time the
-> shock towers were sludge hammered out it looked pretty sad.

When the front end finally gave out in my '70 Torino I yanked the
11.2:1 351CJ and put it in a 1966 notchback. It was *not* a happy swap.
I had to sledgehammer the shock towers, grind the A-arm bolts, and grind
on the manifolds. A couple of places sell headers which are supposed to
work with that swap, but I don't know how they'd run them. The engine
had about 1/16 inch clearance on each side, and I got rid of it before I
had to worry about changing spark plugs. The only practical way (short
of pulling the motor) would have been to cut holes through the

-> > exhaust system. I've been told that the only headers available are
-> custom > made by JBA and have a list price of $899.

Cyclone used to sell some, Hooker still does. They're substantially
cheaper too.

If you really, *really* want the Cleveland in there, check into the
Crites big block conversion. They sell modified A-arms and shock tower
plates. You carve out the stock towers and weld in new suspension
pickups, a'la the Fairlane Thunderbolts. The Crites kit was, as I
remember, in the neigborhood of $300 a couple of years ago. It would
give you plenty of working room around the engine."

My results were much better than either of these. I used special swap
headers (from Total Performance) which ended up requiring a lot of re-work,
but the final product is very strong. The headers are individually flanged
and slip-fit into the header collectors, with two of the tubes passing under
the engine and into the opposite side collector. The swap headers are a bit
big (1 7/8" diameter primaries, 3 1/2" collectors) but they are the only size
available for the 4V heads (1 3/4" primaries are available for the 2V heads).
The approach is sound but the fit quality was pathetic. Initially the
headers were bolted to a spare block for a trial assembly. Bolted to the
engine, the primaries were not even close to fitting into the collectors.
There was steering linkage and oil pan interference, as well. After several
trial fits, all the tubes were re-bent and a couple of sections grafted on.
Still, the shock towers had to be slightly massaged (heated with a torch and
tapped with a body hammer, repainted and undetectable) to get everything to
fit. When I called Total Performance to express my displeasure, I was
informed that 5 out 10 people get them to go together without too much
trouble, 3 out 10 have trouble but eventually get them to fit, while the last
2 just give up! Besides Total Performance, others have swap headers that
will do the job. Their telephone numbers are listed above.

A re-located oil filter was necessary, as was a larger radiator. I used a
larger 3 core unit from a V8 Maverick with A/C. This radiator has different
mounting points so I had to move the pick-up points. This set-up provided
adequate cooling for a previous 351W powered '66, but has proven to be
inadequate for my 351C. It worked okay when I had the stock converter, but
when I installed a high stall speed converter, it was immediately apparent the
heat load had increased. I added an auxiliary tranny cooler but it hasn't
helped much. It sits in front of the radiator and just seems to super-heat
the air flowing past the radiator, reducing its effectiveness.

There are several manufacturers of replacement 3 and 4 core radiators for
64-66 Mustangs, but they are all constrained by the physical size of the
radiator support opening. One of the vendors also makes a late model style
cross flow unit which requires cutting the radiator support opening to match
the (much larger) radiator dimensions. I've not pursued this much since I
plan to switch to a Tremec 5 speed manual, which should reduce the heat load
considerably. If, after the tranny swap, I still have cooling problems, I
plan on opening up the radiator support and and fitting a late model style
cross flow radiator. Wrapping the headers with Thermo-Tec might also help,
but they can turn the headers brittle over time.

switch to a better radiator. need to add info on using Howe or Griffin
cross flow radiators>

One other radiator note. The stock 289 radiator has both the inlet and the
outlet on the same (passenger) side. 351C, 351W, and late model 5.0 engines
all have water pumps inlets that require the bottom hose to be on the
driver's side. Any competent radiator shop can move the lower radiator hose
neck to the driver's side to match the water pump inlet.

One other problem I ran into is the steering box. The '65-'66 Mustangs
have an integral shaft steering box and there's no way to remove it with
the 351C in place. Instead of pulling the engine, I just used a cutoff
wheel and cut the firewall area above the steering shaft. Pulled and
replaced the box then Mig welded the piece back. The trickiest part was
keeping the interior from catching fire (used a helper with wet towels
to keep things cool). Before swapping the engine in, you may want to
rebuild your steering box or, better yet, swap to the non-integral shaft
set up of the '67-'70 Mustangs.

I've re-worked the suspension to match the increased power of the 351C-4V,
so I didn't have any of the traction problems Darius Rudis described
under riders and panhard would probably do the trick but a torque arm is
my preferred approach>. Subframe connectors, Monte Carlo brace, and
export brace are highly recommended.

The 351C really fills the engine bay, but the layout is quite clean. There
are no messy emissions hoses or accessories to clutter up the bay. With a
few customized sparkplug wrenches, the sparkplugs can be changed *without*
loosening the motor mounts and jacking up the engine (unlike my Dad's 428CJ).
I can also remove and install the starter without removing the headers or
disturbing the suspension.

Engine Weight and Dimension Comparison

The following numbers come from an early Ford SVO catalog and are for
"typical" engines. The dimensions include such things as air cleaners, oil
filters, water pump fan, etc., but not bellhousings.

Engine Width Length Height Weight

289-302W 24.0 29.0 27.5 460
302 Boss 24.5 29.0 28.5 500
351W 25.0 29.0 29.0 525
351C 25.5 29.0 29.0 550
351M-400 26.0 29.0 29.0 575

This is consistent with my experience (and other published numbers). As a
check, I weighed several sets of heads and got the following weights:

50.0 lbs 289/302 - complete including rockers
56.5 lbs 351C 2bbl open chamber - bare
58.0 lbs 351C 2bbl open chamber - complete except for rockers
60.0 lbs 351C 4bbl closed chamber - bare

Adding 2 to 3 lbs for valvetrain weight to the 4bbl closed chamber heads,
yields 12 to 13 lbs more per head than a small block Windsor. For the
pair of heads, figure on 25 lbs extra for Cleveland heads. A Cleveland
block may actually be a bit lighter than a Windsor block, since they have
a lower deck and thinner cylinder walls. Thus a 351C should be about 25
lbs more than a 351W (525 lbs vs 550 lbs). The 302 Boss weight estimate
seems high compared to a 302W, especially considering it's aluminum intake.


>Dave told me that he tried to get a 351C into a pre-'67 Mustang and
>that you could even jump up and down on the thing and it wouldn't go
>into the engine bay. Now as I'm wanting to put a Clevor in said space, I
>have to wonder if it won't be the same brand of fun.

If I remember correctly, Dave tried to put the engine in with the factory
iron manifolds. You'd have to hack the hell out of the shock towers to
make it fit that way. With the swap headers, it will slide in, assuming
your shock towers haven't sagged towards each other. I saw one 351W swap
where they had to port-a-power the towers apart for clearance. The biggest
drawback with the swap is the headers have to make an abrupt 90 degree bend
at the exhaust port. It's got to kill exhaust flow but it's the same with
351W swaps I've seen. I've also heard that guys with aftermarket Windsor
heads on 351W's have trouble with the commonly available swap headers.

You'll need a big radiator to keep 430 cubes cool. The stock radiator
is tall and narrow but the grill opening is short and wide. Dump the
stock radiator and cut the radiator support out to the width of the
grill and mount up a Howe or Griffin circle track radiator.

The extra deck height *and* the wider Cleveland heads may make for
trouble. I bet you'd be looking at some re-work of the headers. Things
are tight to begin with.


>Dan, there's always a lot of questions about this swap. I think your
>personal experiences would be quite helpful posted here. I know that I
>would be interested. I've never attempted this swap, but get a lot of
>questions about it.

Okay, I've posted my swap info below. It includes notes about both
351C's and 351W's. Some of the info is outdated now and I've put in
notes to myself to update it here and there where I need to add updates
but you should be able to follow it.

>One misconception is that the Cleveland doesn't fit without cutting the
>shock towers. I've seen at least two of these swaps, using stock exhaust
>manifolds, that required no cutting.

The only ones I've seen that did not require notching the shock towers
were the ones that used custom headers. No way mine would have gone
in with stock manifolds. One big variable is shock tower sag. I've
seen one 351W swap that needed the towers porta-powered back apart before
the engine would go in.

The Mustang Illustrated article that I mentioned earlier mentions they
will be swapping the 351C into a '65 or '66 Mustang using swap headers
and a swap kit from Pro Mustang Performance. It will be interesting to
follow that story.

Dan Jones

Tom at Dawson Racing Headers says he'd make a large primary header for big inch
Windsors in early Mustangs if someone in the SoCal area will use their car as
the mockup. If there's enough interest to make a bulk order so he can do a run
we'd get a buy too! His e mail is and his page is

Hooker already makes a 1 3/4" 351W swap header for 65-70 mustangs. It's part

You can go to and click your way to the Hooker site to get more

What I would like to see is a 1 3/4" header for a 289-302... Seems easy enough,
but nobody I know of makes it.
Motor Mounts: 64 Falcon (early 65) 3 peice mounts or make your own solids.

> Darkhorse tells me that I do NOT need to notch the towers. Is this possible?

Yes it is possible. If the towers have sagged, you'll need to spread them
apart though.

> I think Dan Jones did that a long time ago

Yes, a long time ago. At the time, the FPA headers were not available.
One of these days, I'll get around to updating it.

> Tubular automotive makes a header that routes a couple tubes under the engine
> from side to side. Is this an easy fit or do yo have another style.

I have headers from from Total Performance which are similar to the Tubular
Automotive parts. They are individually flanged and slip-fit into the header
collectors, with two of the tubes passing under the engine and into the
opposite side collector. I run a Shelby quick-steer kit with longer pitman and
idler arms, along with relocated Global West control arms and had some issues
with the tubes hitting the steering linkage.

> Is there anything that I need to watch out for

Run a mini-starter and fit the Monte Carlo bar to see if your shock towers
have sagged. Make sure your steering box is in good shape as you won't be
able to remove it with the 351C in place, due to the long one piece steering
shaft. If I had it to do over again, I'd install a '67 type 2 piece steering
shaft and box.

> and can you recommend the actual header that you used that made it a fairly
> easy swap.

I can not as the Total Performance headers had very poor fit. Bolted to
a dummy block, outside of the car, they wouldn't even go together. Lots
of trial and error fitting involved.

> I know I need the export brace and shock tower (Shelby type) brace if I
> remove the crossmember under the oil pan,

You need those and subframe connectors even if you retain the crossmember.

> so I'm wondering if removing this crossmember is a necessity, or can I
> leave it with certain headers.

The Mustang unibody is not very stiff so it's necessary but it doesn't
necessarily need to be in the factory location or of the stock design.

> Also, is access to Plugs and wires a problem, or just a little tougher.

It's tougher than a 289 but easier than say a '69 Mustang with 428CJ.
I found that buying and modifying several spark plug sockets helped
speed spark plug changes. Specially modified tools can also come in handy
elsewhere. I bent and trimmed some box wrenches to make it easier to do
home alignments.

Dan Jones
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