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Discussion Starter · #1 ·
I want to swap my 3.8 for a 4.6 dohc. I am looking at the mark 8 4.6 since it has aluminum block, and that is a lot lighter than the iron blocks of the cobra. So, is it possible to drop the mark 8 engine into my car? I know I need a wiring harness, and ecu, but is there anything I need to change, or do? I'm not sure of the laws here in PA, but can I put an older engine into my 99 legally with emission tests?
 

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Well, there are a few things to consider. First, it would be a good idea to research your local emissions and inspection laws (if there is any), to see if swapping in an older engine would be illegal. In some states, with strict laws, its very illegal. Secondly, are you pulling the engine yourself.. or are you buying it? If you have access to the car... yank EVERYTHING you can get your hands on. All the wiring harness, the ECU, sensors, brake booster, lines, radiator, hoses, AC, EVAP, fuel system and tank with its wiring.. all of it. This would make the swap alot easier. Now ofcourse, you dont NEED all that stuff, but if you decide to use it... you'll have it. What you do absolutely need is the engine with all its sensors, cooling, exhuast manifolds, front accessories and wiring harness. The ECU in the Mark 8 will be programed for an automatic trans, so you if you want a 5 speed, find a 96-98 GT or Cobra ECU.

The Mark 8 engines use the Teksid aluminum block, which is the most desirable block of all the cobras. Its definately lighter than the iron blocks, but not by much. You'll need a k-member to swap the 4.6 in. You'll also need to reconfigure the brakes to hydro-assist (which i believe was used on the late 98s only, i could be wrong) If there isnt a hydro-assist, you can stick with your power assisted vac brakes. You'll need to reconfigure your cooling to work with the 4.6, and exhaust will need to be modified (H-pipe) to work with the manifolds on the 4.6.

If you stick with an auto, you need to reconfigure your transmission lines to work with the Mark 8s (this is assuming your 3.8 is an auto). If your car is already a 5 speed, and you want to keep it that way, you need to find a T3650, or T45 to work with the 4.6 bolt-pattern. Likewise, if your car is an auto now, and want to swap to a 5 speed with the 4.6, you need to find a complete pedel box assembly, with clutch hardware (includes qaudrant, cable, adjusters etc.) You can make this work, its just alot of work. I havent even mentioned the fuel system modifications. Its likely that you can use your 3.8 fuel system, because it works in return-style configuration.. which is how the Mark 8 motor works. You may have to change out the fuel pump though. Realistically, the car will be down for a few months if your doing this on your own budget, and own time. So be prepared to spend alot of time, and make sure you have another beater car to drive around.
 

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Discussion Starter · #3 ·
I thought the 3.8 was returnless after 99? and i have a 310lph fuel pump, so, that shouldn't be a problem. I plan on keeping my auto trans since it's cheaper. I might have a lead on a mach 1 engine and trans though, so, now my options have increased. Thank You for your help.
 

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It would be cheaper to jut BUY a GT. Unless you have a COMPLETE DONOR car, and are going to do every bit of the work yourself.

I think you've been in the 6er section long enough to know this isn't worth it 98% of the time.
 

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I thought the 3.8 was returnless after 99? and i have a 310lph fuel pump, so, that shouldn't be a problem. I plan on keeping my auto trans since it's cheaper. I might have a lead on a mach 1 engine and trans though, so, now my options have increased. Thank You for your help.
Somehow i missed where your car was a 99, sorry. I should say now that SSStang is making a fairly good point. Price wise, and lack of hassle.. buying a GT or Cobra would be a better road to go down. But, if you have your heart set on keeping your 99, and doing a swap... i'll help in any area you have trouble with, ive been down this road more than once.
 

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And Correct me if I'm wrong but the auto mach 1 motor got the shaft somewhere.... I just can't remember where right now.

It can be done don't get me wrong but. Swaping out 1 motor, swaping in the mach 1 motor, wiring, harness, ecu, gauge cluster, rear end, etc.... Headache. the fuel sytem, the AC all that good stuff.

And then after all that work your probably still gonna hate yourself because the stock mach 1 motor won't be any faster or minimally faster than your s/c v6.
 

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Discussion Starter · #7 ·
well as of now, my car does not run. the belt has decided it does not like being on the alternator pulley and jumps when it feels like it. it's becomming a headache with that as well. I am about 2 minutes away from pulling that s/c off my engine, that's how much it's pissing me off. I have everything I need for the mach 1 engine (if I get it) but ugh. if I could sell my car they way it was, I'd go for a cobra.
 

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well as of now, my car does not run. the belt has decided it does not like being on the alternator pulley and jumps when it feels like it. it's becomming a headache with that as well. I am about 2 minutes away from pulling that s/c off my engine, that's how much it's pissing me off. I have everything I need for the mach 1 engine (if I get it) but ugh. if I could sell my car they way it was, I'd go for a cobra.
From my experience with Mod-swaps... this would be a good idea. Much easier on your wallet and self esteem.
 

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well as of now, my car does not run. the belt has decided it does not like being on the alternator pulley and jumps when it feels like it. it's becomming a headache with that as well. I am about 2 minutes away from pulling that s/c off my engine, that's how much it's pissing me off. I have everything I need for the mach 1 engine (if I get it) but ugh. if I could sell my car they way it was, I'd go for a cobra.
Alternator pulley?!
Weird, what size belt do you have, and what size pulley(vortech). Your alt pulley is stock sized right?
 

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Discussion Starter · #10 ·
yeah, its a stock pulley. it ran perfectly fine until I got it back from the tuners, now it slips off all the time. its a stock alt pulley and a 3.60 vortech pulley. The belt is the reccommended size from vortech.
 

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yeah, its a stock pulley. it ran perfectly fine until I got it back from the tuners, now it slips off all the time. its a stock alt pulley and a 3.60 vortech pulley. The belt is the reccommended size from vortech.
Did you buy the kit directly from vortech?
 

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Discussion Starter · #12 ·
kit? you know my kit was used and I had to get the parts that were missing from vortech... it's the belt they recommended for the 3.60. I'll get the numbers for it tomorrow, I'm in lazy mode right now.
 
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