Skip to main content

Welcome to my 400 Ford engine swap adventure!

I want to start out by saying that this swap requires a fair amount of fabrication and might not be suited for everybody. I am going to provide as much detail as I can for anyone else who might be considering the swap.

I also recognize that there might be some who disagree with this particular route to greater cubic inches and I respect your opinions but I also ask that you respect mine in going this direction.

My motivation for taking on this project started when my 351C short block in my Pantera turned out to be done. It was .040 over with out of round cylinders and had the deck o-ringed but was used with a standard head gasket that had blown. Frowner

My original goal was to build a nice mild 300-350 hp 351C and build a fancy stroker later after I was driving and enjoying the car. That changed when I discovered the engine to be bad.
I found a great deal on a 78 400 complete air cleaner to pan for $200. The block is cast in the Cleveland foundry and is STD bore. The machine shop I use gave me a junk block to use for mock up so I decided to park a 400 short block under my 4V heads and intake. I will be building a mild engine as originally planned... only bigger. Big Grin It is my $200 stroker kit.

A lot of people might not be familiar with the 400 Ford or have been misinformed about it so here are some links to help out with a basic knowledge.
I look at the relationship between the 351C and 400 as similar to a 302 and 351W.The engines are of similar design and architecture with some interchangability.
More information is available than what is listed here but I thought this would be a good start to give everyone some familiarity with the 400. Check em out. Smiler

The topic has been discussed here on the PIBB previously.
Comp2 is also doing a 400 conversion and has done a lot of the ground work for this. Here are some links to previous postings on his progress.

Ford 400

Ford 400 Build

1905 Part Duex
Last edited {1}
Original Post

Replies sorted oldest to newest

With that out of the way let’s get started!

As you should know by now the bell housing pattern on the standard 400 block is the same as a 429-460. I say standard because there were a very small number of 400 blocks cast with the small block bolt pattern.

I looked at my options for the adaptation and found three sources:

1. I contacted Precision Proformance as they had done 460 swaps in Panteras to see if I could buy the required bell housing. I was told that they do not sell any of the parts for this conversion and the car would have to be brought to them for the work.

2. I looked at using an adapter plate made by this company:

My concerns with this part were its effect on the input shaft to clutch and pilot bushing distance. I could make a custom pilot bushing and use a thicker billet flywheel as possible solutions. The price at $795.00 was also pretty high for what it is.

3. I found that Quick time had released their 351M, 400,429,460 to ZF bell housing.

This is a SFI approved bell housing and comes in a kit.
This is the route I chose to go I purchased pn. 8012. At $415.00 I could buy it and the intake adapter for less than the plate style conversion. I did run into a problem as the bell housing is drilled to be used in a GT40 application which is 180 degrees rotated from a Pantera. My solution to this problem was having a machine shop re drill the pattern rotated correctly. Here is the bell housing after drilling.


Images (1)
  • 71908_022rs
To start with I re installed my bare 351C block and ZF. I had to do some repair to the ZF mounts and it is covered in the ZF forum here.

After that I tightened down the factory mounts and built a jig that mounted on the front of the block and located its height as well as centering it. It is made out of a couple of pieces of angle and some square tubing. The front of the block is the same between the 351C and 400 in this regard. Here is the jig mounted on the front of the 351C block.


Images (1)
  • 72608_013rs
I bolted the Quick Time bell to the ZF and my mock up 400 block and installed it in the car with the jig bolted to the front of it.
Then I started on the mounts. The design I created made it possible to access the top of the mount for installing the rubber cushions as well as access to the mount nuts.
The lower plate of the mount is ¼ thick steel and the rest of the pieces are 3/16 steel.
The original cast aluminum upper mount was 3/8 thick. When tightened, the rubber cushion was preloaded against a spacer inside the rubber. I machined 1/8 off of the internal spacer to compensate for the thinner steel I am using to maintain the correct preload.
Here are the pieces to the Right side mount cut out before welding.The Left hand mount is the same as this one. I just didn't photograph the pieces to both.


Images (1)
  • 80208_013rs
Last edited by pittcrew
Here is the project as it presently sits.
I have a old set of 4V heads sitting on it for header fabrication.

I will start out using a set of New GTS ANSA mufflers and will tie the headers to them.
I have another set of ANSA's that I will modify for better performance in the future.

The short list of things I will soon address include:
Swirl and over flow tank mounting. The brackets had been cut out of my car when I bought it so I had to deal with this anyway.
Throttle cable length in regards to the taller engine.
Engine screen fab and mounting.

I have a hectic schedule so these things will take me a while. The bell housing and engine mounts took about a month to complete.

I hope people find this thread informative and helpful.
If it gets too boring I will have Cowboy from hell post pics of hot girls to keep interest. Big Grin
If anyone wants more pics of something posted let me know.


Images (1)
  • 80208_026rs
Last edited by pittcrew
Awesome Brooke, Awsome! So glad to see others doing it. The 400 blocks are a dime a dozen which is nice and it is nice to see others using it. Amazing to me this engine has not been tapped before. It in itself is basically a stroked Cleveland.

Lary one side has the embosement for a Cleveland mount but you would have to drill it and tap it.

Blazing along at a snails pace I finished the water bottle relocation project.

This is not necessary for the swap. I wanted my bottles moved to give me more room for the headers and clean up the compartment a little.

You do however, need to raise the bottle as the thermostat mounting boss on the 400 is higher and this will make the tube higher than the swirl tank.

I made the bracket out of 1 inch angle steel and a piece of 1/8 thick 3/4 wide flat steel.

I made the round cutouts in the angle steel and then welded the flat steel in half circles to it.The bottles are retained with T clamps.
I will add some rubber or another material for insulation later.


Images (1)
  • 082708_016rs
Here are the bottles mounted in the car.
Later I will modify the engine oulet tube to match the angle of the relocated swirl tank.
I removed the existing bracket for the recovery tank and mounted the new bracket there.

The coolant outlet tube still misses the firewall but it is just barely due to the higher location of the thermostat boss.

Next up on the list is finish the shifter install and adjustment, Fab header flanges to match my port plates and build collectors to mate to the exhaust pipes. Then I can start header fab.


Images (1)
  • 082708_017rs
Welcome to the next installment of my build which is 180 header fabrication!

I originally planned to build undercar headers which I will still do…read on.

There will be a long sequence of posts to present this information. I will do the best I can to present the job as completely as I think necessary to convey the ideas and procedures required.

This job requires a fair amount of skill and specialized tools but the most important thing is patience.

I don’t know when it started, maybe it was Rapids avatar or I was spending too much time on You will not find a higher percentage of 180's per capita than with the GT40 crowd. Whatever it was I became obsessed with the 180 Header design. I decided I had to have 180’s.
I particularly liked the Symmetry of this design.

Here is a pic of Rapids awesome 180's that I shamelessly stole from his thread

The reason I did not originally consider going the 180 route is that I wanted to keep my A/C in the rear of the car and I wanted to use my trunk. I decided that although I could keep my A/C with 180's to meet all of my needs I would have to build two exhaust systems. I will build 180’s and a undercar set for use of the trunk when I need the car to act like a car such as going to the fun rally or other long distance events.With the 180's I will also have to build a heat shield to protect the paint on the decklid.

The 180 design header is not for everyone. Like anything else there are compromises. You have to decide if you can live with those factors before determining if 180's are for you.

I have been modifying and fabricating headers for years. I started in 1993 when I did a engine swap (460 in a 69 Mustang) and could not get a header to fit the way I needed it to. After that I began to modify headers for a better fit or collector upgrades, this way I did not have to settle for header manufacturer's design limitations. The first time I built a set of headers out of thin air(Zoomies for a Supercharged 460 in door car tube chassis) was when I could not buy something to fit a custom application. After that it was just something I did when a off the shelf header was not available or what I could buy was not available in a size or configuration I needed.
I don’t make a living building headers it’s just a skill I have developed over the years.

Before I start any project a little research is always in order. For those not familiar with what a 180 degree header is here are some sites to help with the basics.

Please take the time to look at these links. They will answer a lot of basic questions concerning 180 header priciples.
Here on the PIBB you can see where they have been discussed here before.This is one of those threads.

I primarily want to deal with the construction aspect of the build in this thread.

Here is a cad drawing made by Adam C. on GT40s .com it gives a pretty good visual of the typical layout for a set of 180’s. Adam is an engineer who started fabricating GT40 parts as a hobby.
Adam calls fab “art class for adults.”
I love that quote!
Here is a link to his incredible work.

Last edited by pittcrew
I did a lot of searching here on the PIBB and could not find a thread on headers that showed the thought process and individual steps that go into the fabrication of headers. I thought I would do that here in this thread. I apologize for the redundancy if this had been covered before.

Let’s get started.
First thing I did was to make a “wish list” in other words: What criteria do I want to incorporate into my design?
My list is as follows.
1. Headers must allow the use of rear mount A/C unit
2. Headers must be two piece with the only slip together joints present at the collector.
3. Must have descent access to header bolts
4. Must have descent access to spark plugs.
5. Must not have a large primary length difference from one cylinder to another.
6. Must match my MPG Port Plates at the flange.
7. Headers must be easy to install.
8. And most important, they must LOOK COOL!

My headers will be a rifling design where the pulses in the collector rotate in a clock wise or counter clockwise motion. I will mention that I was not able to find a single dyno test comparing a rifling design to a non rifling design. The original GT40 designs that I studied are only rifling on one side.
I am incorporating rifling into my design because I agree with the logic.

Here is a illustration from GT40s .com showing a rifling firing order in the collector. Keep in mind it is not the exact position that is important here it is the order. This order also determines which direction the rotation occurs.

My primaries will be oriented in this order 3258 and 1764
8—3 ----------6—4 Top
5—2----------7—1 Bottom
This makes both sides a clockwise rifling motion with the 13726548 firing order.

Given the modest projected power level of 375 emission legal horses for my 400,
my headers will be 1 ¾ primaries exiting into 2 ½ inch collectors.
My car will be a street use only car. No ORR racing or Track events. As such my engine will be built with a emphasis on bottom and midrange power. I feel the added primary length of the 180 design will compliment this goal. I will chassis dyno my car upon completion of its restoration to validate or invalidate my decisions and make the necessary changes.
Last edited by pittcrew
We will start by fabricating the collector.
These will be a standard 4 into 1 style collector. They will have a 5 inch taper. They are not a true Merge collector but will incorporate some of the internal features of that type of collector. As I understand it a true Merge collector has a much steeper angle.

Here is a great thread on true Merge collector fabrication.

I use a straight edge on end to mark the center of a tube. The tube dia is 1 7/8. This is the slip diameter for a 1 ¾ tube.

Then I lay my template over it lining up the centerline marks and tracing it. It needs mentioning that the template is not a true cone shape as one might think. It flares out drastically at the bottom.

Here are the 4 pieces cut out. I use a high speed cut off wheel to cut them out of the tube.

This is the alignment tool that I use to keep the pieces square. It is available from
This makes the ends of the taper line up with the slip rings that will also be welded in this alignment tool.

Last edited by pittcrew
Here are the pieces tacked together and the ends being shaped for the 2 ½ tube on the end.
I made the jaws out of some ¼ inch steel and welded them to some vise grips.

Here is the 2 ½ end tube tacked in place.

While that is still tacked I start on the slip rings. It is important to sand the ridge from the seam weld flat or it can cause a leak at the slip connection.

Here are the rings installed in the alignment tool and tacked together. They will stay in this tool throughout the rest of the process.The rings are 1 7/8 dia and 1 1/2inches long.

Last edited by pittcrew
Now I start building the Merge bullet assembly. These are the individual parts.

These are super cheap and are available also from
The website also has a great tutorial on the welding of one of their collectors.

Here are the pieces in the aligning tool.

Here is the part all welded and the edges sanded smooth sitting on top of the collector rings waiting to be tacked.

Here is the bullet welded to the collector rings.

Here it is with the finish sanded smooth.

Last edited by pittcrew
I check the fit of the taper assy and the collector rings for alignment then finish weld the taper assy.

Here is the taper tacked to the rings ready for final welding.

If you end up with two pieces that look like lunar landing craft you did it correctly.

Here is a view from the end.I used a 220 grit sanding roll and polished the entire inside of the collector.

Last edited by pittcrew
Header Flange Modification
The header flanges I purchased from Speedway Motors pn# 418-1142. They are 5/16 thick.

I will be running MPG port plates in my 4V heads. The purpose of these plates is to raise the port floor to increase velocity. The problem with the port as cast is the drastic drop off after the short side radius.
It didn’t make sense to me to spend money to correct a problem only to re-introduce it again at the header flange with a drastic drop off into the tube.
Here is the difference between the plates and the flanges.

I went to the Hardware store and bought some square key stock. I then cut it to the shape of the lower opening in the flange.

I then fit them individually into the openings. I made them a little lower than the port plates to that I didn’t have to flatten the bottom of the tube to fit the opening and it allowed for a good transition. At the time the Hardware store only had 3/8 square stock so I had to grind them to fit the 5/16 thick flange.

Here they are all welded up. I will be running a 4V sized header gasket. The opening is below the weld so there won’t be any problems with leaks.

Ready to run some tubes yet?

The tubes I purchased from Speedway Motors, it is their 1 ¾ combo mandrel bend pn# 91013872. I purchased 15 pipes.
The only thickness they come in is 16ga. At about $14 ea they are a good deal for the amount of tube you get and that it includes both a U bend and a 90 degree bend.
Most companies want $15 for just a U bend. I also like how these tubes do not come full of grease like some companies tubes do. This saves having to clean all the pieces with solvent.
They are bare steel that is covered in a light oil that wipes off with Brake cleaner. I also prefer bare tubes to aluminized ones. This saves having to sand the coating off of all the ends to get a good weld at the joint.
16ga tubing has a .062 wall where as the more common 18ga has a .049 wall. This makes the 16ga tubing heavier. I am not concerned about the added weight on my car.

As part of my design, I use the most direct route for the cyl’s that are the farthest away from the collectors. As the cyls move closer to the collector I run the pipes in increasing longer routes to offset the diminishing distance. This will help keep the pipes to a more similar length.

I made a simple tool out of a piece of 2X4, a deck screw and 1/16 TIG rod. This enabled me to mark the tubes for cutting at different degree angles referencing from the center of the radius.

It is difficult to run tubes if you don’t know where to run them to. I made this Erector set looking fixture to mount the collectors so I would have a target to run to. Because I am going to exit at a angle to clear the A/C condenser I positioned the collectors close to the engine. This makes the bends tighter around the block. If I were to exit out the rear of the car I would have moved the collectors much closer to the rear of the car to get a more sweeping motion with the primaries

Here are the collectors mounted in the fixture.

Last edited by pittcrew
*Edit* I wanted to make note at the beginning of this segment that I am not building these tubes to any certain design length.I realize that might sound crazy given the amount of work I am about to do.
I am running them port to collector freehand using the routing I designed and will see where they end up for length. I have not built a set of 180's before or measured a existing set so Im not sure where the dimensions will fall.
I know the currently available undercar headers for a Pantera feature unequal and very short primaries. I am hoping to be able to gain some length with this design.
When my car is done I will chassis dyno it and then have a real number to reference if I need to make a header change. I am not trying to make these equal length because I do not know what length the engine needs. This will be accomplished by the chassis dyno testing.I also do not know how a 180 is affected by a unequal primary. My goal is to keep the discrepancy minimal (less than 8 inches)given the design and the room I am working in. *End of Edit*

I start by mounting a header flange to another 400 I have in the shop. I am not using starter stubs because of the lack of room between the header and the car. I run the number 1 pipe back to the general direction it needs to go. I am using a metal strap to locate the end of the tube so that I don’t run it too low. The Right hand bank cyl’s 1-4 will be the bottom tube set. The LH bank cyl’s 5-8 will be the upper tube set. In order to keep the primary pipes and flanges one piece from side to side I am going to construct them in this overlapping fashion.

I do the same for cyl #2

And #3

I then mount the flange and pipes into the car. I remove the #3 tube to have better access to run the #1 and #2 tubes.
I run the #1 tube first. Where cyl #1 is the furthest away from the collector I run it to the closest collector opening.

I run cyl#2 to the closest opening in the other collector. Since this side of the engine will be the lower bank of tubes I angle the pipe downward as it exits the collector. I need to give myself plenty of room for the pipes that will go on top.

Last edited by pittcrew
Now is when it gets complicated.
I run the #4 tube from the collector to back alongside the #2 tube. I do not connect it to the flange at this time. The reason for running the #4 tube back to there is so that I know where to locate the upper bend in the #3 tube to go over it.

I make the collector ends to the #6 and #7 tubes so that I can see where the #3 tube has to be routed to clear them. Remember the LH cyl bank will be the upper set of tubes.

I then finish the #3 tube

Lastly for this side I run the #4 tube the rest of the way to the flange.

I start the RH bank the same way as the LH side by running the starter tubes while the flange is mounted to another 400.Here is cylinder #5

And #6

I mount the flange with the starter tubes into the car and finish running #5 to the collector.

I then do the same with cyl #6. This side differs from the other side in that cyl#2 went to the opposite collector at the bottom and #6 runs to the opposite collector at the top. Because of these differences one side is not a copy of the other.

I then run cyl#8 from the collector to the front of the engine. I do this so I know where cyl#7 can come up and cross over. I do not take cyl #8 all the way to the flange at this time.

Last edited by pittcrew
I take cyl #7 from the collector to where is starts angling down towards the flange. I have to be aware of how close it is to the fuel tank shield and the gas strut mounting tabs.

#7 gets ran to the flange. Then I route #8 to the flange

Now the headers are ready to be removed from the car and the joints solid welded. After that they will get fit to the car again and the tubes hard tacked to the flanges.
I'm not done yet, lots of work still to do and more collector tricks. Stay tuned for more pics and info to come..

Last edited by pittcrew
Brooke Awesome photos and awesome work. I can't tell you how many things I have picked up from your photos. I really like the collector construction.

I think you should consider writing an article for Car Craft. It would be a great non standard exhaust construction article!

Sorry I have not been writing more. I have been flying my ass off; which is good! We have a couple pilots out and our crews are a little thin. It should ease up late fall.

Thanks for the Comments!

I went back in this morning and added some more pics that I had forgot to post last night. I also did some tweaking to the text.Never ends..

I realized that the way I presented this segment made it appear like these "built a car in a week" reality shows where everything just goes together smoothly.
I want to say that at the point of the last pics you are seeing a months worth of construction time.
Some of the pipes I redid 3 and 4 times to get them right.
It is very tough to build in the middle where you have the beginning and end tube established because the transition has to match perfect.

The cluster at the collector where Cyls #3,6and 7 come together took me 4 hours.

Joules: Getting the primary lengths the same is a debate that has raged on for years in the header community. Sides For and Against are very passionate about their views.

*Edit* Joules, As I reread my above answer I realize that I didn't answer your question at all.Here is my view.

As I understand it,the side for equal length believes that equal length primairies are important to achieve the best scavenging characteristics.They believe this to be from the pressure wave timing being the same from cyl to cyl. They also believe that equal length achieves better cylinder to cylinder balance as the individual cylinders don't go in and out of tune at different RPM's. They believe this also has a positive effect on the intake side of the motor.

As I understand it, the side against equal length believes that the discrepancy broadens the torque band which is benificial to a street car. They also believe that two tubes both 34 inches but one having more bends than the other will not time equally anyway. They also believe that no one knows the correct length to build their headers to so everyone builds them equal to the wrong length.

You can decide who you think is wrong or right for your application. *End of Edit*

My thinking was simply to get them to a similar length to reduce the cylinder to cylinder imbalance and to aid scavenging.

From a construction stand point building a equal length header is very very difficult.
I have done it but I didn't do it here.

Gary, I wondered where you had gone.
1905 is feeling neglected....
Last edited by pittcrew
Here are the pipes out of the car and mounted to a 400 block and heads on a dolly. I can’t bolt them to a engine on a engine stand because they hit the arms on the stand.

This is the RH side header I am very happy with how this one turned out. I want to point out some design considerations on this side of the engine. The header flange bolts are diagonally staggered with the upper bolt to the front. This makes it easy to lay the pipes back towards the rear of the car and still have good bolt access. Because I moved my water tanks this also gives this side more room to run pipe and is easier to build with spark plug clearance. You can also see that the pipes take a longer route the closer to the rear of the engine they get.

Here is the LH header. I don’t like this at all. Frowner The space is so cramped to work in because of the fuel tank shield that you can’t see how it looks very well.

I cut all the pipes off so I could take and tweak that side. It’s better to take some time to fix something that is bugging you now than to have it bother you forever.

Here is Ver2.0 for the LH header. I like this much better. This side the upper header bolts are staggered to the rear of the engine so the pipes exiting the port can’t lay back as far and still have good bolt access. With the fuel tank shield you always have to be aware of how wide the header is during construction. You need to leave room to slide the header out away from the cylinder head for removal from the car.

The other problem the fuel tank shield makes is that the plug access is worse because you can’t run the #5 cyl pipe as wide as you can run the #1 pipe on the other side. The #8 plug will have to be reached from the bottom.Remember I am building these on a 400 which has a taller deck, a 351 will have more room here. Note that I have full access to all my valve cover bolts.

Last edited by pittcrew
Link copied to your clipboard.