4.6 2v swapping on 4v heads

Mar 25, 2020
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Springfield,MO
I have a 4.6 2v engine I will soon be starting to build with a 4.75 stroker kit from MMR, and I was wondering if I could just get used 4v heads and get them ported out, and use those. I was wondering what else would be required for this swap in terms of electrical components and anything that would need to change to make this swap work. thanks in advance.
 
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tsemmett

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Jul 2, 2019
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Yes. You also need the front cover from a 4V, in addition to intake and cooling parts and should consider that the combustion chamber size is larger, which will reduce your compression ratio compared to PI heads (they're close to NPI heads though).
 
Mar 25, 2020
72
5
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20
Springfield,MO
Yes. You also need the front cover from a 4V, in addition to intake and cooling parts and should consider that the combustion chamber size is larger, which will reduce your compression ratio compared to PI heads (they're close to NPI heads though).
, do I need a new computer, is it going to require rewiring everything/anything?
 

tsemmett

Active Member
Jul 2, 2019
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Your PCM can definitely run a 4V, though tuning is likely required.

Electrically, if you install all your electronics from the 2V setup on a 4V, you're really only looking at extending a wire or two (as some sensors are in slightly different places). A 4V typically has provisions for knock sensors that a 2V won't (but I believe that's in the block).

Coil on Plug ignition is the only exception; the 4V coils are wired backwards (polarity is backwards), have a different boot shape, and the wiring runs into the valve cover rather that along the top of the head. You would need to buy a set of 4V coils, separate out the COP wiring from the fuel injector wiring, reverse the wires and extend them to run into the valve cover.
 
Mar 25, 2020
72
5
8
20
Springfield,MO
Your PCM can definitely run a 4V, though tuning is likely required.

Electrically, if you install all your electronics from the 2V setup on a 4V, you're really only looking at extending a wire or two (as some sensors are in slightly different places). A 4V typically has provisions for knock sensors that a 2V won't (but I believe that's in the block).

Coil on Plug ignition is the only exception; the 4V coils are wired backwards (polarity is backwards), have a different boot shape, and the wiring runs into the valve cover rather that along the top of the head. You would need to buy a set of 4V coils, separate out the COP wiring from the fuel injector wiring, reverse the wires and extend them to run into the valve cover.
Thanks a lot that really helps! One other question I have is would ported our 4v heads be better flowing and get you more power than trickflows?
 

tsemmett

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Jul 2, 2019
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The flow numbers I've seen on 4V heads suggests that TFS heads are close to stock 4V heads. Ported, a 4V head should be far superior. Bear in mind that C heads (99-05) are typically better, unless running high boost.
 
Mar 25, 2020
72
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Springfield,MO
The flow numbers I've seen on 4V heads suggests that TFS heads are close to stock 4V heads. Ported, a 4V head should be far superior. Bear in mind that C heads (99-05) are typically better, unless running high boost.
I don’t know anything about 4vs, how many different types are there and which vehicles had c heads and which ones didn’t? And what kind of intake manifold would I need? Could I use one from an aviator?
 
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tsemmett

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Mark VIII and 96-98 Cobras run B heads. 99/01 and 03-04 Cobras, 03-04 Mach 1s, Lincoln Aviators and Lincoln Continentals run C heads. Navigators are similar to a C head, but larger intake (not ideal for a 4.6).

Best option would be a late C head (04/05) as they had more spark plugs threads to deal with plug blow out issues (some 2V heads have that issue too).

For C heads, the 99/01 Cobra/03-04 Mach 1 is your best choice for intake, unless you're looking to run a Terminator supercharger, then you'd run 03-04 Cobra parts.

An Aviator intake will work, but I believe it's too tall to fit under a stock hood.
 

tsemmett

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Jul 2, 2019
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While I'm at it, the 96-98 Cobra cams are an upgrade from the 99-05s (which all use the same cams anyway). Supposedly 20rwhp on a otherwise stock engine. Given the cost of 4V cams, it may be worth considering.
 
Mar 25, 2020
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Springfield,MO
While I'm at it, the 96-98 Cobra cams are an upgrade from the 99-05s (which all use the same cams anyway). Supposedly 20rwhp on a otherwise stock engine. Given the cost of 4V cams, it may be worth considering.
Do you know if the spark plug blow out issue is somewhat rare or does it happen more often than not?
 

tsemmett

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Jul 2, 2019
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I've heard of it more from the 2Vs, but it doesn't seem ridiculously common. They do make a repair insert in case it happens, but if you want to be safer, look for later heads.
 

Nightfire

15 Year Member
Dec 1, 2002
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Basic rule of thumb for these motors is do NOT "convert" your 2V to a 4V. The cost is going to be much higher to do than simply sourcing out a used complete 4V longblock.

Im running an 04 cobra motor on my 2V harness/ECU just fine. A few wires need to be elongated and COP polarity needs to be reversed. Other than that, simple swap.
 
Mar 25, 2020
72
5
8
20
Springfield,MO
Basic rule of thumb for these motors is do NOT "convert" your 2V to a 4V. The cost is going to be much higher to do than simply sourcing out a used complete 4V longblock.

Im running an 04 cobra motor on my 2V harness/ECU just fine. A few wires need to be elongated and COP polarity needs to be reversed. Other than that, simple swap.
I’ve read that quite a lot and that’s very true, but I just want to start completely fresh with new forged pistons, rods, crank, and maybe changing the piston dish to increase compression to get good numbers N/A, or regular piston dish and Procharge it, I haven’t really decided yet
 

tsemmett

Active Member
Jul 2, 2019
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I'd shop around for the stuff; I've certainly seen deals on heads and such lately. Lot of Facebook groups for parts sales.
 

Nightfire

15 Year Member
Dec 1, 2002
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TX
I’ve read that quite a lot and that’s very true, but I just want to start completely fresh with new forged pistons, rods, crank, and maybe changing the piston dish to increase compression to get good numbers N/A, or regular piston dish and Procharge it, I haven’t really decided yet

I swapped out the stock cobra pistons for flat top Manley's. Thats how I bumped up compression (also bored .02 over).....and Im procharged lol. Just need the right fuel
 
Mar 25, 2020
72
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Springfield,MO
I swapped out the stock cobra pistons for flat top Manley's. Thats how I bumped up compression (also bored .02 over).....and Im procharged lol. Just need the right fuel
I’m not sure what I want to do in terms of compression and piston dish, because the best kind of fuel we have around here is 91