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  1. #1

    Default Bbk 351w swap headers pointer at crossmember

    Hey guys I've recently installed a 351w in my 79 coupe with bbk 351w swap headers and both collectors are pointed at the trans crossmember. The passenger side isnt bad and I could probably fix it fairly easily but the drivers side collector is nowhere near inline with the crossmember hump. The collector is sitting more towards the drivers side. Anyone else had this problem? Is it possible to stick a pipe in the collector and bend the header towards the passenger side? I have aluminum heads and really don't know if thats even an option.
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    Last edited by 79mustang; 11-13-2017 at 10:38 AM.

  2. #2

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    Following. Im putting 351 in my 84 and have the same headers b


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  3. #3

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    Didn’t mean to hit b


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  4. #4
    Moderator wraithracing's Avatar
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    What motor mounts and trans mount are you using with the 351W?
    ​Trey

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    Love to see a pic from directly below as I have a set of these and a 351 in the garage right now as well. Probably going to have to heat up the header with a torch to bend it at all.
    Last edited by Dr. Matt; 11-13-2017 at 07:15 PM.

  6. #6

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    Motor and trans mounts are both energy suspension. I've got about 4-5 inches between the collector and the crossmember. I was throwing around the idea of trying to either buy some mandrel bends or pie cut some pipe and try to work it around the crossmember. The headers are coated so i really dont want to torch them.

  7. #7

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    Here's a pic of the passenger side just because
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    Last edited by 79mustang; 11-13-2017 at 08:30 PM.

  8. #8

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    I am in the middle of restoring my 84 and plan on dropping a 351w I am rebuilding in it. I have pondered this potential problem and now it seems to be a real possibility.

    Though my plan has been to go with the MAC headers.....
    https://treperformance.com/i-125882-...tang-5-8l.html

    I wonder if your heads could be influencing the angle of the header as well as it flows down along the tranny tunnel.

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  9. #9
    FEP Power Member dagenham's Avatar
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    I seem to recall hearing about this problem before but I dont recall ever seeing a solution to the problem.
    It seems to me that the headers are made for a 302 which is actually a shorter deck. If they were truely made for a 351 then the tubes should be made to drop down farther to compensate for increased deck height.
    You mentioned the motor mounts. I thought they made a specific motor mount just for this swap that drops the engine down a little farther than stock also.
    Last edited by dagenham; 11-13-2017 at 09:06 PM.

  10. #10

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    Something else I was considering was getting a stifflers tubular crossmember. They don't list one for 79-81 with a c-4 but i contacted them and they told me they could make me one. Does anyone have one of these? I'm sure being tubular, it offers more clearance but i dont wanna buy one and still have issues.

  11. #11

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    Looks like the crewmember could move up another 2" without hitting anything on the drivers side.

    Id make measurements of the trans and driveline angle and modify the crossmember. Looks almost like you could just refill the hole for the bolt, but a crush tube in the new hole and have enough clearance for it to not be a problem.

    My guess is the mock up car had a motor plate or aftermarket motor mounts making it sit a bit different. A bunch of aftermarket k members also drop the motor down a bit.

    Either that or beat the snot out of the connecting pipe near the crossmember.
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  12. #12
    FEP Super Member erratic50's Avatar
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    Convertible mounts are shorter. Solid mounts are also.

  13. #13

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    This may be a dumb question but is your cross member in the right way? I can never remember if the bigger hump goes on the driver side or the passenger side. I think its hard to put it on backwards but that doesnt mean it cant be done! The Stifflers piece is nice for sure, pricey but nice. I had hooker super comps on mine for a little while, they were very close to the shock towers and needed a little love by the steering shaft. They cleared the cross member ok. Good luck getting it sorted.

    Mike
    1982 GT 351W, retro hyd roller, ported Pro Comp heads, Tremec, M2300K brake kit, Recaros...needs paint!
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  14. #14
    FEP Super Member mmb617's Avatar
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    I have the BBK swap headers on my car as well, with the BBK H-pipe. I'm running solid motor mounts and had to massage the stock transmission cross member to get enough clearance on the driver side, but it looks like yours is even farther off than mine was. The passenger side clears the trans cross member easily but the header is really close to the firewall/floor junction on that side. It's a balancing act to get the headers to clear in both those areas. I'm able to get away with some very tight clearances with the solid mounts. I can only imagine the problem is even worse when your motor mounts have some give to them, as more clearance would be needed.

    I have to agree with the poster who said it doesn't seem like these headers were actually designed with the taller deck in mind. If they were just an inch longer in the downtubes all would be fine.
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  15. #15
    FEP Super Member xctasy's Avatar
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    Engine mounts are offset and handed on Foxes, you can get the left and right mixed up, or have two left mounts. The poistion of them then causes other problems in addition to the headers. The whole engine can move 3/4" depending on what position they are placed. Replacement mounts, some Convertable ones can get mixed up.

    On Foxes, you have the option of moving the K member outwards and down. Like all Fords, adding caster always causes front wheel arch contact, but if you look at spacing the member downwards 1/2" with these http://www.maximummotorsports.com/K-...ick-P1268.aspx


    You might get a better fit.


    Running no mounts is what Mike1157 did on his Turbo250 Glia Monster FairFoxMontMercuryThing....if you've got no other options, look at that, and the 1/2" spacers.

    The vibration of a non Cleveland Ford V8 is manily due to its detriot unbalance, the 351W is much nicer than, say , a Cleveland and it slightly gets worse only with bigger cams. Asside from a fully counteweighed crank, you'll most likely find a 351W quite exceptable with solid, un-mounted engine to k member spacers in iron or alloy.

  16. #16

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    I know a guy thats a Four Eyed Pride member that may be able to weigh in on this. He’s running a windsor and he is meticulous so let me hit him up.


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  17. #17
    FEP Power Member Ourobos's Avatar
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    Stifflers is your easiest solution. Otherwise you geometry is off somehow, I squeezed 3.5" collectors with 2" tubes on my last 418w, stock crossmember
    1986 CHP SSP Coupe

  18. #18
    Moderator wraithracing's Avatar
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    I have never compared them side by side with stock mounts or the vert mounts, but my understanding is the Energy Suspension mounts do cause the engine to sit higher in the K member than the stock mount do. The Aero convertible mounts are supposed to be a bit lower installed height for the engine compared to regular mounts and are supposed to be a bit stronger too. I generally use those on all my builds.

    From what I can see, it looks to me like you might want to consider checking your motor mounts to make sure they are installed on the correct side as that could cause some of your issues. Also you might consider using different mounts to see if that will drop the engine low enough to not require major crossmember or exhaust modifications.

    I used the vert mounts with my 351W many years ago in my 85 GT with Mac long tube headers and didn't have any clearance issues, but I have no experience with the BBK headers. Best of Luck!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
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    1986 GT Under going Wide Body Conversion Currently

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    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
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  19. #19
    FEP Senior Member BMW Rider's Avatar
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    Given that the collector is only a few inches forward of the cross member, it would seem that the transmission mount may have more to do with the misalignment. Lowering the engine mounts might help some, but dropping the tail end of the transmission down would have much more effect.

  20. #20
    FEP Power Member Ourobos's Avatar
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    93+ motor mounts, energy suspension trans. mount, 3.5" collectors with 2" tubes, stock cross member - no issues

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    1986 CHP SSP Coupe

  21. #21

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    My understanding is the energy suspension mounts are modeled after convertible mounts which should sit the motor lower than stock. I need to look and see how much clearance i have between oil pan and kmember. Solid drop mounts may be my best option.

  22. #22
    FEP Member vdubn's Avatar
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    If the engine mounts are swapped, it will cause the engine to sit closer to the firewall by almost an inch, and a bit towards the drivers side. I ran into this very issue in my car, even though its just a 302, I had the motor mounts swapped, and it caused all sorts of issues. I am running an AJE Kmember, and AJE solid motor mounts, with a stock trans crossmember, and an original trans mount that is about 1/2" shorter than the new ones I have been able to find. Even the aftermarket Urothane trans mounts are taller.

    Also, is your trans crossmember from an Auto vehicle, or 5 speed? The hump on the drivers side is closer to the drivers side on AOD cars, which is why the X-pipes are all specific to 5 speed and AOD transmissions, due to the width of the AOD. If you are using a 5 speed trans crossmember, then it would be about 2" narrower than the AOD version. Hope that makes sense.
    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  23. #23

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    I've got the mounts in correctly I'm fairly certain. I did try swapping them but the mounts hung way off the kmember pad when i did. The way I have them installed right now.. the mount stud is in the front kmember pad slot and the mounts are sitting on the pads nice and square. The crossmember is the stock crossmember that was in the car. It's an original 302/c-4 car.

  24. #24
    FEP Member vdubn's Avatar
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    Did you order BBK headers that are "automatic" specific? If so, I wonder if BBK makes them for the width of the AOD, and maybe the C4 is narrower? I don't know enough about the differences between the C4 and AOD, but knowing that most of these manufacturers make these parts for the most common combinations, I wonder if the headers aren't for an AOD, but your trans crossmember is for the T5/C4, which might be the same width? Just spit-ballin, might not make a difference between the two.... maybe BBK, MAC, etc. all make the "automatic" versions that fit for both the C4 and AOD, but if they are more specific to the AOD, that could be part of the issue.
    85 GT Hatchback, T-Tops. 2012 Coyote 5.0L Swap, T56 Magnum, GT550 Dept of Boost kit, with Eaton M122 SC, RAM 11" Powergrip clutch, BBK Long Tubes/OR X-Pipe, Flowmaster Axle Back, Stifflers DS Loop, and Rear X-member, AJE Tube Crossmember with AJE-Mod Mounts, 3.73 Posi 8.8, 5 lug Cobra 13" fr and 12.6" rear disc swap, 2004 Hydroboost Swap, MM SubFrame Connectors, MM Panhard Bar, MM front A-Arms, MM rear control arms, MM CC Plates, MM Coilovers w/Koni dampeners, MM Torque Arm (soon to be installed).

  25. #25
    FEP Power Member Ourobos's Avatar
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    The AOD is wider than the C4, even the 164 tooth C4.. If they fit an AOD, they should fit a C4
    1986 CHP SSP Coupe

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