1998 Cobra shortblock vs. 2008 Mustang GT shortblock

[Foghorn]

I have purchased a 2008 Mustang Bullitt with a locked-up engine. The car has 117,xxx miles on it.

I have two 32v 4.6s just sitting around taking up space: a 1998 Cobra engine with about 600 hrs. on it (actual mileage unknown), and a 1995 Lincoln Mark VIII engine with approximately 100k miles.

My thought is to swap the 3v heads (with appropriate maintenance) and front dress on to the 4v shortblocks. This will be a DD type car with an occasional HPDE after appropriate suspension upgrades.

Any thoughts for or against? Any major differences btwn the blocks that would prevent this from being a "hand-tool" type evolution?

Thanks in advance!

 

[01yellercobra]

I'm pretty sure the 4V pistons won't work with the 3V heads. You'll want to check piston to valve clearance. Especially the exhaust valve.

 

[Foghorn]

Reviving this thread. I am getting conflicting info on the exhaust PTV clearance. It appears that 01yellercobra is correct WRT exhaust valve clearance.

The 3V pistons have valve notches where the 4V pistons don’t. Some say if I lock out the cam phasers, I won’t have any problems & others say I’ll have problems no matter what. Does anyone have firsthand experience with this?

Does anybody have info on flycutting the pistons like we did when putting TFS twisted wedge heads on the SBF 5.0 ?

 

[01yellercobra]

How much is the peace of mind worth to you? Though it looks like the notch needs to be in the very bottom. You could always do some garage clearancing and send it.

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Why not bolt the head on and check the clearance with the cam advanced and retarded? If it clears at least you'll know which way to lock it.

 

[Foghorn]

Just wanted to close out this thread for now. If I get around to checking the PTV clearance and actually fly-cutting them, then I’ll post results.

I decided to do a gen 1 coyote swap. At the end of the day, it was less work but a little more $$.

 

[01yellercobra]

Probably a better way to go in the long run too.