Exhaust port mismatch - FFR headers to cylinder head.

[CW_MI]

Has anyone ran into this issue ? These are the 302 headers, and a Dart cylinder head. The headers are a rectangular port, while the cylinder heads are not. A Blueprint Engine pic found online, has the same exhaust port configuration as the Dart.212670212671212672212673

[Jim1855]

I've seen similar mismatch. I believe that the rectangular ports of the headers are more traditional old style Ford ports. The heads have a more current higher flowing port design.

I don't think there's a good way to fix it short of new headers. The heads also have the 2" and 3" bolt pattern. The 3" is way nicer to use, the 2" squeezes the port.

Jim

[Ford & Jeep Fan]

how does the header fit at the top of the port? That is much more important. I would NOT worry one bit about the bottom (AKA Floor) of the port. The port velocity is much lower on the bottom of the port.

[CW_MI]

how does the header fit at the top of the port? That is much more important. I would NOT worry one bit about the bottom (AKA Floor) of the port. The port velocity is much lower on the bottom of the port.
You can see in one of the pictures, its close to a 1/4" on the top of the port, along with the sides, which aren't quite as much.

[8secDuster]

how does the header fit at the top of the port? That is much more important. I would NOT worry one bit about the bottom (AKA Floor) of the port. The port velocity is much lower on the bottom of the port.

I'm not a head porter, and do know the roof is more important than the floor, but.. the floor mis-match would still create turbulence which would hinder flow. That's why everything is port matched, even exhaust ports / headers.
Just surprised there isn't more mention of this on here since F5R offers aluminum headed (square port) Blueprint engines.
Unless it's by design.

[ggunter]

This is a problem for sure with FFR headers as they do not match cylinder head ports very well unless you have old style Cast Iron heads. The close 2" bolt spacing makes it even worse which doesn't allow any room to open them up. Outside of a custom made set of headers using the 3" bolt spacing so the ports can be made to match I don't know of a good way to improve this. I bought a set of Gasn headers and Georgie asked me if I wanted the 2" or 3" spacing on the flange. Looking back I wish I would have asked for the 3" spacing which would at least allowed some room to open up the header ports a bit. I ended up not using them for other fitment issues. Has anyone found someone who makes a custom set that addresses this issue. Of course, when you look at the entire exhaust system on the Roadster it has to be horrible for the engine to breath. 4 into 1 then 4 into 1 before it comes out the pipe. The exhaust has to be very confused.

[CW_MI]

This is a problem for sure with FFR headers as they do not match cylinder head ports very well unless you have old style Cast Iron heads. The close 2" bolt spacing makes it even worse which doesn't allow any room to open them up. Outside of a custom made set of headers using the 3" bolt spacing so the ports can be made to match I don't know of a good way to improve this. I bought a set of Gasn headers and Georgie asked me if I wanted the 2" or 3" spacing on the flange. Looking back I wish I would have asked for the 3" spacing which would at least allowed some room to open up the header ports a bit. I ended up not using them for other fitment issues. Has anyone found someone who makes a custom set that addresses this issue. Of course, when you look at the entire exhaust system on the Roadster it has to be horrible for the engine to breath. 4 into 1 then 4 into 1 before it comes out the pipe. The exhaust has to be very confused.

The only thing I can think of is to replace the header flange. A fabricator should be able to do this. Here is a site where one can order new flanges for the different exhaust port shapes on SBF heads.
http://www.spdexhaust.com/Ford_B.html#

Or order the Gas-N headers and specify which flanges one wants.

[ggunter]

CW that is a great website. I didn't know anyone was making header flanges. That pretty much solves the skinny port situation. All one has to do is cut your old flange off and weld on the new one. At least in theory it looks like that might work.

[ggunter]

Of course the FFR tube are somewhat square, but a little torch work they could be convinced to conform to the new flanges.

[CW_MI]

Of course the FFR tube are somewhat square, but a little torch work they could be convinced to conform to the new flanges.

Yes, hopefully they can accommodate the new shape. A good fabricator should be able to do it.

[bobl]

Most FFR 302 headers are 1 5/8" tube. Those heads need a 1 3/4 tube, with the 3" bolt pattern. Best to order the correct header from Gas N and sell what you have or maybe return them if they are new. By the time you buy new flanges and pay a good welder you'll have spent as much or more than buying new header, plus you have the potential to get them out of alignment when rewelding.

Bob

[Jim1855]

New headers would be the best plan and the easiest.

BTW I designed and had flanges laser cut from 3/8" SS304. Then a friend built 1-7/8" headers to my side pipes. They came out well. Only downside is the project was expensive but the only way I could get what I wanted.

Jim

[CW_MI]

Most FFR 302 headers are 1 5/8" tube. Those heads need a 1 3/4 tube, with the 3" bolt pattern. Best to order the correct header from Gas N and sell what you have or maybe return them if they are new. By the time you buy new flanges and pay a good welder you'll have spent as much or more than buying new header, plus you have the potential to get them out of alignment when rewelding.

Bob

While it shouldn't cost anywhere near $1k to change the flanges, it definitely would be much less of a hassle to not have to go that route.

[CW_MI]

Being that there aren't too many replies on this, and so many people seem to be using the BP crate engines, which have the larger bolt pattern/port shape, are they just bolting on the FFR headers and running with it ?

[ggunter]

Pretty much everyone uses FFR or Gasn headers because they don't reinvent the wheel to get an exhaust system that works, and they are available. I still agree they don't breathe well but the whole exhaust system is a bit funky.

[CW_MI]

Pretty much everyone uses FFR or Gasn headers because they don't reinvent the wheel to get an exhaust system that works, and they are available. I still agree they don't breathe well but the whole exhaust system is a bit funky.

Understood, and that is exactly what my friends intent was. There was no reinventing the wheel. The FFR header is designed for a stock iron rectangular port head, even the BP motors come with an aluminum head with a different exhaust port design. I would think with FFR and BP collaborating, they'd update the header.

[Ford & Jeep Fan]

To the OP, So the entire port on the head is lower than the ports on the headers?? I assumed since you didn't show the top mismatch of the port it was aligned correctly. I have mig welded and ported more than a few sets of headers to make them work in the past. Haven't seen too many 302 heads that far from most headers though.

It really looks like whoever programed the port placement in the best place for flow did not talk to whoever programed the machine to drill and tap the bolt holes.

[CW_MI]

Being that there aren't too many replies on this, and so many people seem to be using the BP crate engines, which have the larger bolt pattern/port shape, are they just bolting on the FFR headers and running with it ?


To the OP, So the entire port on the head is lower than the ports on the headers?? I assumed since you didn't show the top mismatch of the port it was aligned correctly. I have mig welded and ported more than a few sets of headers to make them work in the past. Haven't seen too many 302 heads that far from most headers though.

It really looks like whoever programed the port placement in the best place for flow did not talk to whoever programed the machine to drill and tap the bolt holes.

Picture #3 at the bottom, has a view from inside the port looking out, it shows the roof of the port compared to the gasket, its also roughly the same on the sides.

[Bob Cowan]

This has been an issue forever. The header port being bigger than the head port doesn't seem to be much of a problem, unless you're racing and need ever last bit of torque.

But the gasket can be a real problem. It blocks a lot of the port, and provides very little sealing surface near the bottom. I've tried a number of different gaskets, and they are all the same. Then I started using red silicone gasket maker. Lasts for years, and fits the header flange perfectly.

https://i.imgur.com/fTWHj2o.jpg

https://i.imgur.com/DKCCFSN.jpg