Smoke23

currently in in the process of gathering all the parts for my LSx swap. My biggest issue so far is finding long tube headers. I have a MM k member w/ 03 Mach1 power rack & MM steering arm. I've looked and can't find who has headers that will fit properly. Who here has used the MM kmember.

usdmholden

I can tell you that Accufab / Pro Mustang 8.2 deck headers with LS flanges will not fit on a MM 4.6L k member and mounts in a fox. On the pass side header only one tube fits, sort of, and the drivers side, three tubes fit.

You will have to try the various swap headers to see what fits. I'm just making my own headers.

Smoke23

Only thing I've found close are the 351 headers w/ LS flanges..

v8sten

iTrader: (5)

id say pull that k-member out and put an aje k-member in there and save you all the headache. thats what i would do

streetlegalls1

iTrader: (15)

Hind sight is 20/20 on my swap but i would have went AFCO and Dynatech.Sell what ya have and save your sanity

usdmholden

If you are building a drag car or plan to run skinny tires on the front of the car there is no reason to keep the MM k member. All benefits inherent to suspension and steering geometry which the MM k member provides will be wasted by driving in a straight line and/or not having enough contact patch on the front tires. Used you could probably sell the MM k member and A arms for enough to pick up either the whole LS front end swap kit or the headers brand new.

ReefBlueCoupe

351 swap headers with LS flanges are still the only "good" way to do this.

I've been going back and forth with one of the MM techs, and there is still no off the shelf header for this swap.

I find it funny because BBK already makes a header for a Coyote and MM K-member. There are probably more LSx/MM K-member cars out there than Coyote and MM K-member.

You can go with the cheaper K-members if you just want something easy, but MM stuff is top notch and worth modifying the headers in order to use.. It's really not a big deal. The flanges are cheap, a metal/fab shop can do the work for a few hundred bucks, then you can test-fit to make sure they're good, send them off for coating and you're done.

351 swap headers are cheap and always available used, and most already have the factory-style ball-and-socket flange used with most Mustang exhaust systems.

usdmholden

I have not tried but I suspect you can fit the BRP swap headers which fit the stock k member, use an fbody or Holley 302-2 oil pan, and build your own motor mounts, and it will fit.

Again, I have not tried it. The only reason I have not tried is because I have the 4.6L MM k member and the motor mount stands on the 4.6L k member are extremely large. Doing it over again I would use the 5.0 k member and build motor mounts to fit, which is what I ended up doing on the 4.6L k member anyway.