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Discussion Starter #1 (Edited)
If cost is a limiting factor, there is no 4.6 DOHC Modular engine donor choice less expensive than a 1994-1998 Lincoln Mark VIII, especially if you plan to run the desirable IRS rear suspension.

The SOHC Mustangs can be a worthy alternative…but…at 2 to 4 times the initial cost of most Mark VIII donors.

With the SOHC Mustang you get a cast iron block that is heavier than the DOHC aluminum Teksid block found on the Mark VIII… plus a modular SOHC engine produces about 50 HP less than a Mark VIII DOHC….

With the Mark VIII you also get the highly desirable…some would say the “best” rear street suspension for an FFR. Everything you need, except the shorter axles, comes on the Mark. The shorter axles are supplied in the FFR IRS kit. The IRS is judged to be a more satisfying street suspension by those who have built both the IRS and solid rear axle cars. A search on IRS will find MANY posts from builders who have stated their preference for IRS handling and ride quality, or have stated that their next cars will have IRS suspension. The straight axle can be made to achieve excellent skid pad numbers, but cannot offer the same ride quality as the IRS. The money saved by going the Mark VIII donor route can effectively pay for the IRS option when ordering your FFR kit.

With the Mark VIII you get the best of both: the more desirable DOHC engine and the IRS…all for substantially less money than ANY Modular Mustang donor. There have been numerous Mark VIII donor cars bought for $535-$1,000. The least expensive SOHC Mustang donor I am aware of was $1800 with many closer to $3K. Late model Mustang DOHC donors are typically $3500 to $9000 or higher. And all except the high dollar Cobra SVT lack the desirable IRS.

For many, the Mark VIII is becoming the donor of choice where good ride, handling, and excellent power for minimal cost is a priority.

In a nutshell you get a DOHC with substantially more horsepower than the best SOHC Mustang and only 15-20 HP less than the 96-98 DOHC Cobra Mustang motor. You get an aluminum IRS rear carrier. You get a radiator and Fan Assembly that is superior to the mustang. You get a car that has not been dogged like many Mustang donors and has likely seen better routine service and maintenance. But the real killer...is that you can find a 50K to 80K mile Mark VIII donor for less than $1,000. Cheaper than even a SOHC Mustang donor...! It is also cheap enough to allow you to buy more new or rebuilt components as you build. Something that becomes harder to cost justify when you spend several thousand more for the donor upfront.

You can buy a good running moderate to low mileage Mark VIII for less than $1000. I have seen one sell for $535 with 76K miles.

The Lincoln interior, wheels, tires, sunroof, electrical components, climate controls, doors, trunk, glass, et al...can be sold for far more than the cost of the donor Mark VIII... What you sell off the Mark VIII will effectively provide a 280-290 HP DOHC Engine, wiring harness, radiator and shroud, transmission, gages, and complete IRS for FREE...!

With what you save over buying a comparable 4.6L DOHC Cobra with equivalent mileage, you can buy NEW gas tank, sending unit, aluminum radiator, spindles, brakes, etc. and still come out ahead. For MANY items I would prefer to have new or rebuilt over a used Mustang donor part anyway.

For the non critical Mustang donor parts where used is as good as new...the local Pick-N-Pull will supply the odd items that can't be used from the Lincoln.

Plus much of the small hardware is common to both donors, and in some cases the Mark VIII parts are superior to the Mustang. Case in point is the radiator shroud and cooling fan. Many Mustang guys seek out the Mark VIII fan and shroud for better cooling.

Keep in mind also that the Mark has the best overdrive automatic that Ford has ever built. With a simple "J" modification and a 2800-3200 stall converter, this combination in many roles is superior to a manual transmission. Don't sell the 4R70W short...it is an excellent trans well suited for high performance...and it comes standard... in the Mark VIII.

Further, most Mark VIII's will be better maintained and far less abused than a Cobra Mustang.

Until the prices of Donor Mark VIII's start climbing...I would contend you can build a combination of Mark VIII Donor car with MANY new parts added for LESS than the $3500-$9000 now being quoted as the going purchase price for 4.6L DOHC Mustang donors.

With the Mustang donor you end up utilizing far more USED parts to keep cost down because of the much higher initial purchase price. Although you can still recoup a major portion of this cost by reselling parts you don't need, you are still into a car that initially cost 4 to 9 times what a Mark VIII will cost. With the Mark VIII it simply becomes much easier to justify buying more new parts.

If you are definitely going DOHC and IRS...the choice is clearly in favor of the Mark VIII.

What Parts can I use From a Mark VIII Donor?

Over the past several months, I have received a number of questions asking what parts From a Mark VIII donor car can be used in the building of an FFR Modular 4.6L DOHC.

What I have tried to do is to provide the following overview of what will… won’t… or… “may” work with modification. In addition I have added any helpful comments regarding each part.

The following is a list of 1993-1998 Mark VIII donor parts that CAN be used:

The 4.6L DOHC Engine. Many people do not realize that the 1993 Mark VIII was the first all aluminum DOHC 4.6 modular engine produced by Ford. It was the forerunner of the 96-98 Cobra DOHC, which was simply a refined version of the Mark VIII engine, designed for a lighter Mustang with manual transmission. The early Mark 4.6 is rated at 280 HP compared to the later Mark rated at 290 HP. However, don't let the 290 HP of the later Marks fool you. The higher rating was due to an improved exhaust system on the later Lincolns, while the late intake manifold is actually more restrictive and less desirable than the early Mark intake manifold. By comparison, the 96-98 Cobra is rated at 305 HP. This slight power increase was due to an improved intake used on the early Cobra for use with a manual transmission. The early 94-96 Mark uses an intake slightly more restrictive than the 96-98 Cobra intake but less restrictive than the later 97-98 Mark intake. The exhaust cams on both the Mark VIII and early Cobra are identical. The Mark intake cams have about 10 deg less duration with the same lift, to improve low end torque for use with an automatic transmission. With an equal exhaust system, all three engines are very close to each other in output. The Mark uses a different oil pan, with a side reservoir, but either OEM oil pan should be replaced with the much superior Champ pan and baffle.

The 4R70W Automatic Transmission. The best automatic transmission Ford has used in a passenger car. Some would argue it is the best automatic transmission ANY manufacturer has used in a passenger car. However, internal improvements were made after 1998 making the transmission even more durable. If you plan to use the 4R70W and yours is in need of a rebuild, have your transmission shop re-build to the 2001 and later specifications. Or use the original transmission as a core for a later model 4R70W.
Since the Mark VIII never offered a manual transmission, those wanting to convert to manual will have to locate the transmission, bell housing, clutch and flywheel from other sources. “FasterPatrick” on the forum can provide details as he has made the conversion on his car.

The IRS rear Suspension.The Mark VIII donor provides most of the necessary the IRS components. FFR will supply the rest with the IRS package option. Go with the IRS and you will never regret it. Many builders of the 3 and 4 link rear ends have stated that their next cars will have IRS. The IRS is a better match for a “high performance” but comfortable street car.

IRS center section. The Mark VIII uses an aluminum carrier as opposed to the T-Bird or Mustang which uses a cast iron carrier. It is lighter yet strong enough for a serious street car. The one down side is that the Mark VIII uses an open rear end. I have yet to see or hear of a Traction Loc being available as a factory option. However, a standard 8.8 Traction Loc carrier can be installed easily. Just be aware that the IRS requires a different pair of side spider gears to accept axle retaining clips. Side gears for a T-Bird Traction Loc can be substituted or the original side gears can be machined to accept these clips.

Engine and transmission Mounts. The factory engine and transmission mounts can be used, however it is strongly recommended that aftermarket Polyurethane mounts be used to minimize engine movement. Such mounts can be bought from eBay for as little as $79 a set for the engine mounts and $29 for the transmission.

Mark VIII Donor wiring harness and ECM. The primary contribution of the wiring harness is the wire itself, the connectors, engine and transmission power control modules and sensors. The Mark VIII supplies what you need just as well as a Mustang donor.

ABS. The complete Mark VIII ABS system can be used. It is compatible with the Mark VIII power master cylinder or the early Mustang 96-98 Hydroboost.

Rear brake calipers, rotors and hubs. The rear Mark hubs with 5 x 4.25” wheel pattern can be used and re-drilled to the Mustang 5 x 4.5” wheel pattern. One of the forum members offers this service. Just do a search. The rear Mark VIII calipers are actually a better part than the Mustang rear caliper as they have a larger piston with more clamping force. New Mark VIII rotors can be used or larger diameter Mustang Cobra rotors can be used after fabricating a small caliper mounting bracket.

Radiator and Electric Fan / Shroud. The Mark VIII radiator is close enough to the Mustang in size to make using it feasible. In my case, the radiator was damaged so I bought a new Mustang radiator online for about $100. The fan and shroud from the Mark VIII is actually superior to the Mustang and is highly sought after by Mustang owners and off road 4 wheel drive vehicle owners.

The Driveshaft. The Mark VIII aluminum driveshaft can be shortened and used, but because the aluminum shaft is highly sought after by Mustang owners, it makes more sense to sell the Mark shaft for $100-$150 and buy a new shortened steel drive shaft from a vendor such as Breeze for $275.

The fuel filler neck and gas cap. Since only the upper portion is cut and used from the Mustang filler neck, The Mark can supply this portion of the filler tube just as well as a Mustang. Note that the new LeMans Gas Cap supplied by FFR no longer needs the upper Mustang filler neck, so this part on newer kits can be disregarded.

The following are Mark VIII parts that CANNOT be used without major modification and should be replaced with Mustang components:

Fuel Tank. The Mark has a different shape and size that is not adaptable to the FFR tank location. New Mustang fuel tanks can be bought off eBay for less than $100.

Front Spindles are totally different. Should be replaced with 94-95 Mustang spindles and hubs. If you are planning to run ABS, be sure to get spindles having the ABS rings installed.

Front Brake Calipers and rotors . Plan to buy new Mustang rotors and rebuilt calipers . Either late GT or the larger Cobra rotors with aluminum PBR dual piston calipers will work well.

Front Lower Control arms. Will not interchange. Order replacement M-3075-D LCA’s from Ford Racing for as little as $137 a set with new high durometer bushings and new high quality ball joints. Or the tubular arms from FFR for about $500.

Automatic Pedal Box. It is shaped completely different than a Mustang pedal box. However, I found an automatic 94 Mustang pedal box on eBay for $.01 plus shipping. $15.01 total. Something to note is that the automatic Mustang parts go CHEAP on eBay. If planning to run a manual transmission then a Mustang manual pedal box will be needed. An identical 94 Mustang Manual pedal box sold for $26 from the same seller.

Power Steering Rack. The Mark VIII rack is approximately 10 " shorter overall than a 94 Mustang rack. In my case I found a Brand New 94 Ford Mustang PS unit on eBay for $85…!! However, the Mark VIII rack may serve well as a core if you buy a rebuilt Mustang unit from your local auto parts store.

The following are Mark VIII parts that “May” be used with some adaptation or modification by the builder.

Accelerator Pedal. The Mark rubber pedal is slightly different but the assembly will work. Keep in mind that the Mustang gas pedal has to be modified and MANY do not like the modified Mustang pedal when done. A better solution is to buy an aftermarket pedal for $100 and sidestep the issues of modifying and using either OEM pedal.

Master Cylinder / Hydro Booster. It looks like the Mark PS mastercylinder may fit, but it is larger than the Hydro booster and may interfere with the FFR chassis. I have not tried to trial fit one. In any event, a used 96-98 Mustang Hydroboost can be bought for as little as $35 from one of the yards on Car-Part.com

Instrument Panel Gauges (modified similarly as the Mustang instrument panel) It appears that some if not all of the Mark VIII gages can be made to work when cut and modified as called out in the builder manual. However, I have yet to convert these gages. The modification process would be similar.

Alternate Parts Sources

Keep in mind that MANY parts you want will be remanufactured parts from Napa or AutoZone, etc., where you can return used Mark VIII cores when buying the rebuilt Mustang parts. Many stores don’t care, just as long as a rebuildable core is received, although it would be best to first discuss with the store to insure they are agreeable. This allows you to buy many needed Mustang parts in rebuilt condition, using the Mark donor for cores. This is especially helpful for items such as brake calipers.

I Need Your Help and Input

I have tried to be as accurate as possible, but please use this information at your own risk. Keep in mind that this guide is an ongoing document that will be revised with new information added as we all learn more about using the Mark VIII as an alternate donor to the Mustang. I would ask those of you who have chosen Mark VIII donors for your builds to PM me on any useful information with details that I can add to this list to make it more accurate and more helpful to other new builders.

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