Fresh Rebuilt 240

[pmuller9]

Lets say you want to make peak torque around 3500 rpm with a 90% VE and a cylinder size of 40 cu in.
Using Pipe max or other calculators or Diameter = rpm x CID/88200 you get pipe sizes less than 5/8"

However that is for naturally aspirated engine.
A forced induction engine has far more exhaust volume and the pipe diameter should be larger.

The Hedman header pipe flange is smaller than the port and will cause a problem with flow.
In this case the flange and the entry portion of the primary tube needs to match the rectangular exhaust port shape.
The end of the primary pipe should be formed to the rectangle shape.
The stock cast iron exhaust manifolds are that way.

I would say use the 1 3/4" pipe and form the end.

[THE FRENCHTOWN FLYER]

I hammer form the tubes into the rectangular ports of the flanges.This means stretching out the corners to fit tightly.
A 1 5/8 pipe is sufficient for the street, and it clears the intake ports easier.
Tack weld the tubes on the outside, then fully weld them up on the inside against the head. Dress off any weld beads protrude into the ports. I like to leave the tubes inside the flanges about 1/16" to make it easier to get a clean weld bead.
Mandrel bent tubes work best. You need really tight ones at the flanges - 3" R?

[pmuller9]

That's good to know.
The 1 5/8 will make it easier at the collector end also.

[sandboxer]

Thank you for the feedback FF. I built a hammer form yesterday so I tried to make sure that the flow out wasn’t impeded in any way.

Today I checked the outlet on the EFI header and it matches the exhaust port perfectly (1500sq mm). Ford’s 3 into 1 has no pinch spots at all. I checked the outlet on the Hedman collector and it is a perfect 1500sq mm as well, but as was determined, is pinched from the flange to the exit. I’ll post a few pics soon of my hammer form.

Thanks

[sandboxer]

A few pics:
The exhaust form is protruding about 1” more than needed because I’ll weld onto the flange with a slight anti reversion lip so the width and height will be slightly oversized to the port opening.

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[pmuller9]

Nice form and flanges!
Will you use stainless steel tubing?

[sandboxer]

Nice form and flanges!
Will you use stainless steel tubing?

Thanks!
The flanges were made by Lunatic Fringe.
I’m going to use 1 3/4” .065 mild to start. It has a 1 5/8” opening, which will meet my needs. I’m going to try this header on the dyno against the EFI, and hopefully it’ll come out better. If not, I’ll cut and paste and try again...
3-1 then 2-1 for full scavenging.

Stainless will be for when I have the dynamics figured out.

[54-4x4]

You are doing a very nice job on your pieces.I will be tagging along to learn something here.

[sandboxer]

You are doing a very nice job on your pieces.I will be tagging along to learn something here.

Thank you. It’s definitely quite a learning curve for me. I’ve fabricated before but never to make horsepower, so I’ll tag along too:)

[sandboxer]

My header transition effort. A few more attempts and it might start to clean up a bit...
I’m planning on sliding the tube over top and grinding out the inside after weld up.

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The extra inch on the transition will disappear after I figure out the exit angle.

I’m picking my tubing tomorrow so I’ll hopefully have some progress photos by the weekend

[THE FRENCHTOWN FLYER]

NICE

[54-4x4]

That looks good what you are doing.

[sandboxer]

That looks good what you are doing.

NICE

Thanks gentlemen.
Here are a few shots from today’s work.

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A shot with my intake runner and one with a 1.75” tube ready to be bent.

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[sandboxer]

A little update
Intake runners taking shape.
Debating the use of TRW forged pistons for a 300. These are beautiful but heavy. Obviously not for the 240, but thinking about my .030 rebuilt 240 and putting these in with a 300 crank...
.060 offset.
Compared with a TRW cast piston, it’s quite robust.

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[sandboxer]

Stitching up the runners

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[54-4x4]

You are doing a fine job.I like to do this kind of stuff too.

[sandboxer]

You are doing a fine job.I like to do this kind of stuff too.

Thank you! It’s a good thing I didn’t post pics of my epic screw ups:)
Please share your adventure pics.

[sandboxer]

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...add a little flare...

[sandboxer]

Rough carving my crank before polishing and balancing. Leading and trailing edges...

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[sandboxer]

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All of the casting flash has been removed and the hard edges smoothed out. Given the odd counterweight shapes, I didn’t feel quite right putting this in the lathe and trimming them down.

Can someone advise me whether I should chuck it up and spin a bit off, or should it be left as is?

Or start over...

[sandboxer]

Decided to start carving. No water yet:)

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