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Headers to fit '72 Mach 1 w/400 engine
#1
Hi guys, need some help on this one! Just added another 71-73 Mustang to the family. This is a '72 Mach that someone has dropped a built 400 in to. Because of the taller deck height this engine is slightly wider than a 351C and because the 351M-400 used a big block bellhousing bolt pattern it has the big C6 trans. Any idea if a set of 351C 2V headers will clear? I don't know how much  clearance 351C 2V headers provide normally in a 71-73 Mustang, so I'm in the dark. I think there's clearance to the shock towers for headers but clearing the big C6 is unknown. Appreciate input, this engine is recently built and appears to have had some money put into it, so I'd like to keep it.  Thanks

1971 Coupe - 306ci (circa 1971) - 10:1/750 Holley/RPM Air Gap/Lunati camshaft (221/231@.050)/Comp roller rockerarms/Ford Racing pulleys/Ported cylinder heads/MSD ignition/Patriot Ceramic LT headers/Single Chambers/Carter fuel pump/NOS Sniper/9" diff./4.57 gears/B&M Holeshot convertor/B&M Shiftkit/B&M Z-Gate/CE subframe connectors/Jegs Sport Star rims/Lakewood traction bars/Fiberglass Ram Air hood/Electric fan/Rear seat delete/Relocated battery/Custom graphics

1972 Mach 1 - 400ci/C6/Quick Fuel 750/Weiand Intake/Harland Sharp rockers/Performance cam/Patriot headers/CVF racing underdrive pulleys/Jegs Sport Star rims/Traction bars/Accel distributor/Miloden 8-quart/Jones Full Boar exhaust/Hurst Pro-matic 2 shifter
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#2
(03-19-2019, 07:36 AM)MeanMachine Wrote: Hi guys, need some help on this one! Just added another 71-73 Mustang to the family. This is a '72 Mach that someone has dropped a built 400 in to. Because of the taller deck height this engine is slightly wider than a 351C and because the 351M-400 used a big block bellhousing bolt pattern it has the big C6 trans. Any idea if a set of 351C 2V headers will clear? I don't know how much  clearance 351C 2V headers provide normally in a 71-73 Mustang, so I'm in the dark. I think there's clearance to the shock towers for headers but clearing the big C6 is unknown. Appreciate input, this engine is recently built and appears to have had some money put into it, so I'd like to keep it.  Thanks

Wow, 60+ views, no response. I knew it was an uncommon swap but thought someone would have some insight Sad  

So, let me pose this question instead to those who have headers on their 351C: How much clearance do you have from the shock towers and around the steering box & transmission with your long tubes? Thanks guys!
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#3
You might want to consider block hugger style shorty headers. Your biggest problem will likely be steering box clearance. I believe Sanderson, JBA, Doug, and Patriot make something that may fit.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#4
The 400 C6 should not be a problem since the 429 C6 has the same bell housing bolt pattern. There is that odd ball early (73 Ranchero I think) 400 that had a small block bolt pattern. I don't know about the headers, could be a challenge. Chuck
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#5
Thx, if the dimensions I found are correct, the 400 is only about an inch or so wider than the Cleveland, so my hunch is 351C 2V headers might clear but being taller means floor plan clearance could come into play....might have to take the plunge and just try a set
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#6
If you have oil pan clearance, and assuming you have stock 351C motor mounts, you can lower your engine about an inch by using '73 frame mounts. That should help floor pan clearance, but may make steering box worse. More information and links here:
https://www.7173mustangs.com/thread-moto...tification?

These headers are supposed to fit 400s in Mustangs
https://www.centuryperformance.com/sande...ory_id=280



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#7
Great info Don. Appreciate it. Those headers look very similar to Doug Thorleys
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#8
Sounds cool- I never heard of someone running a 400 in a '71 to '73 Mustang, or any Mustang for that matter. I know that the engine exists, but it always makes my brain think harder because I had two Pontiacs with 400 engines in them, and I don't think of it for Ford right away. Even Mopar has a 400 in some of their 1970's performance cars.
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#9
(03-22-2019, 04:25 PM)donkost Wrote: Sounds cool- I never heard of someone running a 400 in a '71 to '73 Mustang, or any Mustang for that matter......

Me too, at first I thought someone had thrown a Cleveland in it. But I did my homework and found that in many ways the 400 (technically 402) is a larger version of the Cleveland and has great potential. Found several posts of basic engine builds of the 400 exceeding 300 HP and 450+ TQ. The engine in my car has been modified by a PO, and has 4V carb, weiand intake, performance cam, Harland Sharp rockers, extra cap oil pan, Accel dizzy, etc. So I'm hoping to add headers to help it breathe a little better. I plan to scope the cylinders and hope to find flattops Wink
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#10
Well after spending quite a bit of time trying to get a used set of long tubes to work with my setup, I settled on shorty headers. I found a very nice, affordable set from Patriot (H8435) that looks like it's going to work great for me. It appears there aren't many options for 351C shortys for 7173 Mustangs...….and since I have a wider, taller 400 engine, well, I wasn't 100% sure they'd fit, but so far so good! Thanks Patriot!

I'll be posting a separate thread about these headers with pics, for anyone else interested in seeing this product in a 7173 engine bay

Also, thanks for everyone's help and info here Wink
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