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Temp DOHC Exhaust Manifold(s)

1K views 5 replies 5 participants last post by  dDUBb 
#1 ·
As I've brought up before, I'm slowly working on getting a DOHC 4.6 in my Cougar. I currently have a stock motor from an 05 Aviator on the stand. The thing is I want to swap the motor in briefly to make absolutely sure I have everything I need for the swap, and more importantly, make sure my wiring is all correct, since I'm not coming from any stock harness, but a MN12 Chassis harness that has been heavily modified to accept a 99-04 Mustang PCM and a modified Mustang Engine harness. As such, I had to modify a Mach 1 harness to get it to mate up with the body harness. Because of this, despite pinout tests, I want the engine in the car running for a brief time to be SURE everything’s right before I tear it down for a real built motor.

The main hang-up is the exhaust. I will end up with true dual exhaust, and ideally longtube headers, or at least mid lengths (Yes, I know SCP is the only place to get the Kooks mid length and Longtubes are really only possible by modifying MAC Mustang LTs), but for the brief test run, I do not want to modify the stock exhaust as after a successful test, the SOHC would go back in for the duration of the build since it will take time and I want the car drivable.

I have both Mark Manifolds, but the problem is I don't have a complete DS manifold as the yard hacked the converter off so I do not have the flange, so I can't even attempt to make a custom fab. In theory, a complete non-LSC mark Y pipe should fit the car, so if I could find that and a complete DS manifold, that would be an option, but it's something I don't want to spend a lot of money on as it would be (very) temporary.

Now, here's my hair brained idea/question... In looking at the DOHC & SOHC Manifolds, I've noticed that the bolt pattern is identical, and the SOHC flange (barely) covers the entire DOHC port. Would using the SOHC manifolds on the DOHC heads function for a brief time without damaging anything? Obviously, it would be a huge restriction and one would in no way want to run this for any extended period of time, but would it be safe to do for a brief function test of at most a short drive, possibly not even leaving the driveway?
 
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#2 ·
I can't answer that question, but if you have the driver's side manifold, even without the cat, you could weld a flange onto it, and test that way. Also, if you want to keep your car on the road while you build the motor, I would suggest getting another car to do your test fitting. You could pick up a 4.6 MN12 with a blown motor, or major rust or something for a few hundred bucks, and do all your test fitting on that car, then when you are done, transfer everything into your car, and not have to bother with multiple engine swaps in your car.
 
#4 ·
I can't answer that question, but if you have the driver's side manifold, even without the cat, you could weld a flange onto it, and test that way.
Where would I find a proper flange? The DS Manifold I have is stainless, not cast, so welding it shouldn't be a problem, but finding a flange I can weld to it could be... I've been looking in the local yards for a Mark that hasn't been processed yet that I might arrange to get the flange cut off the cat for me, but no luck so far.

Also, if you want to keep your car on the road while you build the motor, I would suggest getting another car to do your test fitting. You could pick up a 4.6 MN12 with a blown motor, or major rust or something for a few hundred bucks, and do all your test fitting on that car, then when you are done, transfer everything into your car, and not have to bother with multiple engine swaps in your car.
The problem is the physical fit isn't my concern. It's the electrical 'fit'. My car is one of a kind with the PCM and wiring modifications, so getting another car wouldn't help as far as testing it in my car.
 
#3 ·
No.
 
#5 ·
Since the 2v has a flare on the LH side, it should seal up on a ball type flange, which an exhaust shop should have in stock or could at least order for you. You can always just get a 2 or 3 bolt flange and weld it in on either side and use an appropriate gasket. You can get those from the same places.
 
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