Hedman Hedders for 3x00 Configuration as RWD

[WhiteRaider]

I was thinking about purchasing a set of these to cut up for my engine swap. Screw California and their silly laws. The 3100 will get much better emissions than my carbed 87 4 banger! I'll just keep the thing registered in Texas.

Anyway, a guy on an Isuzu 4x4 forum put a set of these headers on his 3.4l iron head in his trooper. The Isuzu guys have the starter on the drivers side (drilled and tapped for that side) so I figure that these would work for me. They are Hedman 69250 .



Raven had mentioned in another thread that it would be possible to just notch the mounting holes to install them on the 3x00 heads. Before I buy them, I just want to make sure that the runners will line up with the exhaust ports on the aluminum 3x00 heads though. If not, it might make more sense to build totally custom headers.

Anyway, can I just notch the mounting holes, or are the holes so far off that I'll have to cut off the flanges and weld new flanges on? Do the tubes line up on the aluminum 3x00 heads? Either one is no biggie, assuming that the ports line up.

[Guest]

RE: Hedman Hedders for 3x00 Configuration as RWD

You will also need to change the shape of the port. I thought I mentioned that.

The genI and genII uses a round exhaust port, the genIII uses a D-shaped exhaust port.

If you are planning on staying N/A, I'd probably start with that set, and make the small modifications to them, as building complete headers can be a PITA to do.

[WhiteRaider]

You will also need to change the shape of the port. I thought I mentioned that.

You did. I just forgot about it.

So, what are we talking about as far as work goes on that? Some filing and grinding to make the flanges into a D shape, or will I have to cut off some tubing and add larger tubing directly behind the flange as well?

[bszopi]

I wouldn't say it's 100% necessary. TOG makes headers for the 3x00s and they use round ports. They are larger than the port opening, which may make a difference.

[Guest]

I wouldn't say it's 100% necessary. TOG makes headers for the 3x00s and they use round ports. They are larger than the port opening, which may make a difference.

Yes Brad, that is the difference here. The Hedman Hedders have the same size port as the genI/II ports, and will cover part of the genIII ports when used.

Basically this is how I'd do it, I'll try and explain it.

Use a due grinder to open up the flang itself to the proper shape, the stock gasket is a great guide for this. Then you will notice that there will be some material that needs to be added, using some small diameter tube, maybe 1/2" to 3/4" cut some triangular piece length ways with the tube and use that to fill in the new port shape to round tube.

[WhiteRaider]

Use a due grinder to open up the flang itself to the proper shape, the stock gasket is a great guide for this. Then you will notice that there will be some material that needs to be added, using some small diameter tube, maybe 1/2" to 3/4" cut some triangular piece length ways with the tube and use that to fill in the new port shape to round tube.

That's definitely doable.

Another idea I've been thinking about today was to purchase a set of flanges for the 3x00. I'd cut down the outside dimensions Hedman flanges and then weld the 3x00 flange directly ontop of the existing hedder flange. That would solve the bolt hole problem and then I could file the inside of the hedman flanges so that the transition would taper into the 3x00 flange a little smoother. This would also give me a little more space between the starter and the exhaust. Thoughts?

[Guest]

Use a due grinder to open up the flang itself to the proper shape, the stock gasket is a great guide for this. Then you will notice that there will be some material that needs to be added, using some small diameter tube, maybe 1/2" to 3/4" cut some triangular piece length ways with the tube and use that to fill in the new port shape to round tube.

That's definitely doable.

Another idea I've been thinking about today was to purchase a set of flanges for the 3x00. I'd cut down the outside dimensions Hedman flanges and then weld the 3x00 flange directly ontop of the existing hedder flange. That would solve the bolt hole problem and then I could file the inside of the hedman flanges so that the transition would taper into the 3x00 flange a little smoother. This would also give me a little more space between the starter and the exhaust. Thoughts?

That's also an idea.