Problems With 351W Shorty Headers - Need Help

[SCFFR]

Just getting started on the under the car exhaust system on my MKIV and as luck would have it, have run into a significant problem. Researching older posts I read that shorty headers for a 351W in a 79-93 Mustang would work (swapping left side for right). I checked the FFR manual and it referenced the headers from MAC so ordered a set from CJ Pony Parts. I was told it would be 4-6 weeks since it was not an inventoried item and would have to be made. So, after 5 weeks I followed up and was told that MAC hadn’t even started on them (yeah I was upset). I cancelled the order and got my money back and then ordered a set of BBK headers for the same application through Summit Racing. The headers arrived in three days so I started fitting them to the engine. The passenger side fit perfect with plenty of clearance but the two rear tubes on the driver’s side header hit the inner footwell panel. When I say “hit” I mean I couldn’t get the header even mounted on the engine. Looks like the rear tube would stick into the panel about 2".

So, has anyone used/found a set of shorty headers for a 351W engine that does fit?? My two options if I keep the BBK headers would be to cut a hole in the footwell innner panel and build a recess box/panel and rivet it in the opening. Even this might be a challenge since I just did some more close measuring and looks like the header pipe would come through the panel exactly in the same spot where the square support tubing is located.

The other option is to find someone to modify the headers to bring the rear two pipes closer in to the flange. Of course, I have the ceramic coated headers so that would get messed up and I would have to get them recoated...........if that can even be done. Has anyone had a set of headers modified before?

Any help would be greatly appreciated.

[Beal]

I am finishing up a 351 install on a Mark 3. I used what are referred as swap headers which in theory will position the outlet at the same position as in would have been on the 302. I have not tried to install the side pipes yet but I have no issues with foot box clearance. See divers side pic. Passenger side all kinds of room

[SCFFR]

Thanks!

Can you tell me what brand of headers you are using? I will return the BBK headers and get what you have. A part number would be great if you have it.

Ron

[Beal]

I am using Ford Racing swap headers part #M-9430-A58. I found them on Ebay but they have not been produced for awhile so you may have trouble locating the ones from Ford. Several other companies make them, BBK 1511 and there were others. I noticed now you have a Mark 4. Are the foot boxes the same or did they enlarge them on the 4? Good Luck

[SCFFR]

Thanks again.

Will see if I can find the Ford headers on eBay. I have the BBK 15110 headers and they will not work without cutting out the footwell panel.

I think the Ford number listed is the one specified in the FFR manual but I could never find them anywhere. Like you said, they haven't been produced in a while.

Ron

[rich grsc]

You look here?
https://www.yearone.com/Product/DisplayProduct/442205

[MDR]

Like Beal I am working on the 302-351 swap, I bought the BBK shorty swap headers (mkI)
they do not clear the driver side footbox. I removed the footbox panel and used a sand bag and a hammer (plastic round head) from Harbor freight to "blister" the area to allow room for install. A bit redneck but it turned out well and is not that noticable.

Mike

[SCFFR]

Thanks again for all of your replies.

Yes, I did see the headers on both the Year One and Mustangs Unlimited websites. Will follow up with them both to see if they are original Ford Racing parts (i.e., leftover inventory) or some type of knock-off. Most importantly are the headers in stock. I've found that many companies keep items listed even though they don't carry them anymore.

[johnnybgoode]

I've got a 351 in a MKII, it was installed by the original builder but as best as I can tell it has BBK Equal Length Shorty Headers (that must be for a 302 as I don't believe they make them for a 351?) I can take some picks if you wish, I'm pretty sure the J-pipes have been modified for these as I bought a new set and they do not fit the same as the old ones. Regards Scott

[sgspeed]

I have a 302 with BBK equal length shorty headers. They come close, but do not touch the side panel. Do you have the equal length headers.

[SCFFR]

Just wanted to thank everyone for their feedback and input.

Was able to find a pair of NOS Ford Racing headers on eBay that will hopefully fit. They are the part number A58's that have been out of production for some time and are the ones mentioned in the FFR manual so maybe they will clear the footwell panel. If not, I will have to see if I can modify them since the choices are very limited. MAC and Ford no longer make the ones recommended in the assembly manual and the BBK swap headers don't fit.

The Ford headers should arrive next week and I will be able to see how they fit.

Many thanks again!

[SCFFR]

Happy to report that the obsolete Ford Racing shorty headers (#A58) that I got on eBay fit the 351w engine in my MkIV with about 1/2" of clearance between the rear tube and driver's side inner footwell panel. I really lucked out in that I was able to find a NOS set in the original Ford box with gaskets and hardware and the price was $199. Now that the headers are bolted into place, I can start fabricating the under car exhause. Will be using Spin Tech oval tubing and low profile mufflers. Should be able to keep everthing pretty close to the bottom edge of the 4" main tubes.

Thanks again to everyone for their help.

[emac]

Great. Fwiw, my shorty headers are ceramic coated, and the j pipes are not. Just for fun, I took one of those thermo temp scanners and the difference in temps b/n the headers and j pipes was about 150°! The ceramic coating is very impressive. I would consider ceramic coating them.

Edit....I am going to send off my j pipes to get ceramic coated.