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Discussion Starter #1 (Edited)
Is there a preferred year of Mark VIII donor to use?


My preference is for the 95 or early 96 Mark VIII because:

They do not use PATS, which was implemented late in the 96-model year.

They have the early style intake manifold, which is reportedly less restrictive than the 97-98 manifolds.

Lincoln changed valve guide seals in early 95 to the same size used on the 96-98 Cobra. The 93-94 seals are harder to find and if the late seal is used with the early head...they will leak oil.

The 95-96 Marks are less expensive as donor cars than the 97-98 later body style.

The 95-96 Marks, being newer, generally have fewer miles than the earlier 93-94 models.

The 96 models have an added advantage over the 95 and earlier Mark as Lincoln went to the same conical valve springs and retainers in 96-98 that were also used in the 96-98 Cobra DOHC. This is a superior valve spring and retainer combination. However they can easily be retrofitted to the earlier Marks.

Having said that, it has been reported that the very first production Mark VIIIs in 93 used forged crankshafts, then went to cast cranks on all remaining Marks. I am not certain this is accurate information, but for me this is a non issue as the stock Cast Nodular Iron crankshaft is plenty strong for up to 600HP...and it has better wear characteristics than a non-nitrided forged steel crank.

The one noteworthy advantage that the 98 Mark VIII models have over earlier years, are slightly improved internals in the factory supplied 4R70W transmission. But most will want to replace or rebuild the transmission anyway to implement the best selection of internal parts. I don’t consider this one advantage enough to offset the other less desirable issues with the 98 models.

Some will point to the slightly higher HP ratings of the 97-98 engines as an apparent advantage. However, the advantage was due to a change in the exhaust system, not an engine advantage. Since the factory Mark VIII exhaust system will not be used on the FFR this becomes a moot point. In actuality, the later, more restrictive 97-98 intake manifold likely produces less HP… that was offset, to a degree, by the freer flowing exhaust system.


Can a Lincoln Continental with 4.6 DOHC be used as a donor like a Mark VIII DOHC?

NO… The Continental will not work unless you have another RWD block and can transfer all engine parts. The Continental has a FWD bolt pattern on the bellhousing and is not the same as the RWD bolt pattern of the Mark VIII. However, the Continental engine uses many common parts with the Mark VIII if your just needing engine parts.


How can I determine if a Mark VIII donor Engine is good?

FIRST...take a 5/8 spark plug socket with 8-10" extension and pull the plugs. Make sure they are dry and relatively clean with minimal oil residue. The ideal plug will have a color on the sides of the center electrode insulation that looks like a 10 year old dried out Hershey Bar... A light tan to medium brown color.

If you can turn the motor over with the starter, do a compression check. Any more than 5-8% variation may be a problem. If you can't, you may still be able to turn the motor over by hand and do a leak down on each cylinder with the piston at TDC on the compression stroke...but be careful. The crank has to be positioned at each TDC position and kept from turning as the compressed air will try to push the piston to BDC...usually with a lot of force. Leakage of no more than 5 - 8% in any one cylinder is good.


Can I use the Mark VIII aluminum driveshaft?

Yes…You may want to shorten it and use it, but because the FFR driveshaft ends up being so short, there really is little advantage in weight savings and shortening an aluminum shaft will be more expensive than shortening a steel drive shaft. You may prefer to sell it on eBay as the Mustang guys will pay $100 for one.


Can I use the Mark VIII radiator, fan and shroud?

The Mark VIII radiator is different than the Mustang radiator, but it can be used. The fan and shroud assembly definitely should be used, as they are better than the comparable Mustang parts and better than 95% of the aftermarket fans on the market.


Can the Mark VIII brakes be used?

Yes and No…The front single piston Mark calipers should be replaced with dual piston aluminum Mustang GT PBR front calipers and 10.8” diameter front rotors or Cobra PBR front calipers with 13”diameter rotors The rear Mark VIII calipers can be used with the stock Mark VIII rear rotors or can be used with larger Mustang Cobra 11.56” vented rear rotors using a simple fabricated mounting bracket. The Mark VIII power master cylinder should be replaced with a hydroboost from a 96 and newer Mustang.


Can I run a manual transmission instead of the Mark VIII automatic?

Yes. You need a flywheel with 6 bolt pattern for the 4.6L, clutch. bellhousing and transmission. FasterPatrick on the FFR forum has done the conversion and can offer details.


Does the Mark VIII IRS come with Traction-Loc?

On this I am not certain. All of the information I have found indicates that Mark VIII center sections were all open rear ends. However, some have reported seeing Traction-Loc on LSC models. But Lincoln states the LSC was a higher final drive ratio...but not Traction-Loc. In any event, a standard 8.8 Traction-Loc carrier can be installed with spider side gears from a T-Bird Traction Loc IRS. These side gears have an added machining operation to allow axle retention clips to be used, which are not found on the conventional straight axle Traction Loc side gears.

Kerry
 
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