Ford Racing 427W X Head header options

[RobW33]

I've searched this topic it seems a million times and I can't find a clean answer. I'm looking for shorty headers that will fit my 427W X Head crate motor that won't interfere with anything in my MK4 build. I've seen posts regarding the BBK 15100 having issues (but they don't seem to be a problem with the 302 based motors). I would like to have a J pipe I can connect the oxygen sensor to. I'm not interested in absolute peak performance, so anything that fits would be nice to know about. I do have the FFR side pipes. I have to believe there are a lot of builders out there with this motor.

It's my understanding that the 351W based motor with X heads has the same mounting as the 302 but I would assume the deck height changes the geometry for the J Pipe. I don't understand how the BBK 15100 header would interfere with this setup and not the 302.

Thanks in advance!
Rob

[skullandbones]

I think the deck height affects the type of intake manifold you use but the head will actually fit a 302 or 351 engine. There is some minor drilling so the heads will accept the larger head bolts/studs of the 351W. So if I'm wrong on this I will be very disappointed as I plan on using my new heads on both types of short blocks (on my 302 and then switching to a new 351W short block). I think you will have no issues with your J pipe fitment.

Good luck,

WEK.

[RobW33]

Thanks for the quick reply. I did a little checking and yes, the X-heads can be bolted to either 302 or 351W blocks so you're right about heads being interchangeable. So any header that fits the 302 should fit the X head as well. I actually have a set of 302 headers I got when I purchased my kit that bolt right up to the X heads but they are the long tube headers. I assume they don't mate up to the side pipes because FFR sells a different part for 351W engines. This is further complicated because I need to install an oxygen sensor and I don't see a good location for this in the long tube headers.

I did happened across a site that describes everything needed to swap a 302 to a 351W and they noted you need to use "351W swap headers" which allow connection directly to the existing pipes in a Mustang. I think these are needed since the 351 is a bit taller after installation on the common motor mounts. For clarification, the BBK 302 headers are part number 15150 (not 15100 like I stated above) and the BBK 351W Swap Headers are part number 15110.

Everything I've read about online implies that the 15110 swap headers interfere with the footbox but most information is from MK3 installations and I'm assuming the 15150 302 headers will be geometrically off a bit for the side pipes. Hence my quandary...

I have to assume there a number of 351W installations with X heads (or GT40 heads) that have a clean solution that doesn't involve custom/expensive parts. If not, I'll just buy the 15150 302 headers and have a custom J-Pipe fabricated, which I assume would be a cheaper route than custom headers.

Thanks,
Rob

[CDXXVII]

Custom Headers. Talk to the guys at gp headers. They may already have a set of headers configured for your setup. You can add double collector like mine or place your O2 sensor in you side pipe after the collector. Either way GP headers build a great product that actually fits correctly.

http://www.gpheaders.com/

Here are the headers they made for me. I had them built to line up with Georgie's Gas-N Pipes with double collectors. My O2 sensor is actually installed on the passenger side. The double collectors are actually really hard to see once the body is installed.

46198