do the valve covers off of a mark 8 fit a 96-98 cobra? I know they both have the b-head, just not sure if bolt pattern is the same? Also is it worth picking up a teskid block out of 94-96 mark 8? My local pick-n-pull has a few of them, and I was wondering if it would be worth my time to pull one. What else is worth the time to pull off a mark 8?
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i thought they were the same motor part number for part number BUT check that because im not sure ..
they are not the same motor. they are close but not the same. the cobra has a steel crank and the mark doesnt. the cobra and mark intakes are different obviously and the heads are the same casting as the cobra but the cams are not as agressive in the mark as the cobra. im not sure on this but i think the mark only has a 6 bolt flywheel compared to the cobras 8 bolt flywheel.
but to answer your question the valve covers will fit.
but to answer your question the valve covers will fit.
Correct on all counts my good man. Figured I'd stick to the technical stuff for my 1st post.
The valve covers will fit, and as a matter of fact, even the coil on plug style valvecovers use the same bolt pattern. One thing to watch, however, is that they do take different gasket sets. If you get the fel-pro kit, I have to say the doughnut gaskets are vastly superior to the OEM ones in that they don't fall off as soon as you flip the valve cover over. The fit is much more snug and the sealing surface is better.
As far as the Teksid block... really, the standard WAP block will hold up fine unless you're talking 8-900+ HP monster motors. Teksid is also about 5# heavier but thats enough to ignore. The forged cranks have two advantages if performance applications. Firstly its harder and stronger, not that thats an issue in most applications. But if you're building a high revving engine, a more rigid crank will ultimately lead to better bearing life at high RPMs and less harmonics. Speaking of harmonics, the forged crank also lacks the center counterweight that the forged cranks have. Keep in mind this is just something I've heard and can't personally verify, having never put them side by side. Harmonics play a special role in modern engines like ours, with over-the-crank oil pumps. I've heard harmonic issues tend to contribute to premature oil pump failure in high RPM applications with stock oil pump gears. Keep in mind, again, thats just "what I've heard" but it seems plenty plausible and when it comes to your oil system, do you want to take that chance?
One thing to watch is the breather port location, as it will be different depending on which valve covers you're using.
Because of that I ran into an unforseen difficulty on my engine: The "B" head style valve covers won't clear a 1998 Mark VIII intake on the passenger's side.
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The cast cranks do not have the center counterweights therefore are much lighter. If I remember right, the weight difference is 10-12 lbs. The cast cranks are commony used in NMRA factory stock engiens that see 7500rpm and hold up quite nicely.
go ahead and and take the whole motor if its cheap enough. that way you will have a spare block and a spare set of heads to build to minimize down time if you want to port and polish them.
Now theres something I didn't know!
Maybe I'll just have to keep mine after all :coolman:
Keep in mind a competitive team in a NMRA stock class will be doing a tear down one a year and undergo a complete inspection. Further, its important to remember that these cars only drive 1/2 mile at a time: 1/4 mile at balls out, and a 1/4 mile coasting down the return road (plus pit driving). You're talking a couple hundred miles per season max.
So while I agree with na_svt that the cast crank is fine for moderate duty performance applications (all Mustang GT's have cast cranks), I disagree with the comparison to a NMRA/IHRA/NHRA stock or superstock engine setup as an indicator of reliability for a daily driver.
You do make a valid point.
I'm still rolling around options in my head and honestly, I can't afford to not do things right the first time at this point in my life. Which means when I finally get around to tearing this engine apart, I won't be cutting corners. And if the higher revving cars came with the Forged unit from the factory, I'm sure it was for a good reason.
I'm still rolling around options in my head and honestly, I can't afford to not do things right the first time at this point in my life. Which means when I finally get around to tearing this engine apart, I won't be cutting corners. And if the higher revving cars came with the Forged unit from the factory, I'm sure it was for a good reason.
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