CNC Header Flanges

[markandson]

Another member here mentioned that there were some fit issues with the flange when they made from your template. I can't get Inventor to open the darn thing so I am not really worried about using the other CAD file since I've already created one based off of the 2.4 exhaust manifold I have. If you could send me an IGES file of the model so that I can compare the three designs that would be great.

It is a .dwg file from AutoCad 2004, no 3D model exists, I believe I posted it as a .pdf, maybe the other members did not use mine, I printed a full size one on my plotter and then cut it out with an xacto knife and it fit perfectly. I would have to search for it myself, I don't recall what the thread was. I still have the original Acad drawing, PM me your email address and I will send it to you.

[Paul]

The problem I found was interference with the thermostat housing. The other tweaks were very small adjustments with the bolt clearance holes to improve the ability to get all the manifolds bolts in easily. We're talking .020 to .030 nothing major.

I cut mine on the water jet at work. First, I cut it on 18 ga sheet metal and kept making very small adjustments, checking against the 3 heads I have.... and then cut one out of 3/8 hot rolled plate. I made mine so it would fit a head modified to Bob's street porting article, which should still work okay with the stock head.

[Gumby]

I received Rallybob's version of the flange today. The divider between the two cylinders is about .1" and I also noticed that the thickness of the flange is actually less than 3/8"... The sand blasting removed about .004" from each side.

A few other things I noticed.

This flange has a 1.22" width for each exhaust port but the 2.4" manifold I have various from 1.38 - 1.42". So it is a bit larger. Is there merit to using one size over the other? In either case the width is larger than the exhaust ports.

I can faithfully copy Bob's design or just as easily make any improvements. Is there any census as to which way to go?

[RallyBob]

I received Rallybob's version of the flange today. The divider between the two cylinders is about .1" and I also noticed that the thickness of the flange is actually less than 3/8"... The sand blasting removed about .004" from each side.

Finally! That took forever to get there.

This flange has a 1.22" width for each exhaust port but the 2.4" manifold I have various from 1.38 - 1.42". So it is a bit larger. Is there merit to using one size over the other? In either case the width is larger than the exhaust ports.

Well, even with extreme porting on Gregg's 2.4 head, the header flange I used on my most recent header fits with no issues. I can't imagine having to make the flange holes any larger.

I can faithfully copy Bob's design or just as easily make any improvements. Is there any census as to which way to go?

Whatever is easier for you. If you can make some improvements, I say go for it! Maybe widen the center partition a bit? The fabricator/end user could always grind it away 'if needed'.

Bob

[Gumby]

Well, even with extreme porting on Gregg's 2.4 head, the header flange I used on my most recent header fits with no issues. I can't imagine having to make the flange holes any larger.

I couldn't think of a good reason either. The corner radius on your flange is much closer to the stock ports on the head… the exhaust manifold is more than twice that size!

Whatever is easier for you. If you can make some improvements, I say go for it! Maybe widen the center partition a bit? The fabricator/end user could always grind it away 'if needed'.
Bob

That isn't a bad idea. The stock 2.4l ports are more than .2" way from each other. That would give more material to weld to and make it less likely to warp.

I'll get cracking on the updated model this week.

[Gumby]

It is a .dwg file from AutoCad 2004, no 3D model exists, I believe I posted it as a .pdf, maybe the other members did not use mine, I printed a full size one on my plotter and then cut it out with an xacto knife and it fit perfectly. I would have to search for it myself, I don't recall what the thread was. I still have the original Acad drawing, PM me your email address and I will send it to you.

I received the model just fine via email. I'll compare it against the model I already have and Rallybob's flange tonight.

Paul: Which CIH engine did you have interference issues with the thermostat (1.9, 2.0, 2.2, 2.4)?

[Gumby]

The model markandson sent me was spot on. No clearance issues so far on the 2.4L but I have to get the manifolds off before I can test it on the 1.9L in the GT right now. I'll have enough metal stock to make 18 flanges tomorrow. I hope to be making swarf by next week. Turbo headers are to follow.

Thanks for the drawing Jeff!

[Paul]

I received the model just fine via email. I'll compare it against the model I already have and Rallybob's flange tonight.

Paul: Which CIH engine did you have interference issues with the thermostat (1.9, 2.0, 2.2, 2.4)?

It was on a 1.9

I don't remember if it was interference or I just was concerned that it might have been real close....I'll go back and pull my sheet matal templates out and recheck this weekend.... however my home computer crashed last night, so I might not be able to post results until Monday when I get back on my work computer....

[Gumby]

It was on a 1.9

I don't remember if it was interference or I just was concerned that it might have been real close....I'll go back and pull my sheet matal templates out and recheck this weekend.... however my home computer crashed last night, so I might not be able to post results until Monday when I get back on my work computer....

It checked out fine with the FI thermostat housing. I'll be pulling the manifolds on the 1.9L this weekend so I can make sure it fits properly. Jeff's model is almost exactly the same as Rallybob's so I don't think there will be any issues.

[Gumby]

UPDATE:

After a slight delay last week the metal stock is sitting next to my mill.

So far my count is this:

7 mild steel flanges
2 stainless steel flanges
1 mild steel turbo header
1 stainless turbo header

Right now I have material to make 11 mild steel flanges and 6 stainless steel. Obviously I have more material than has been purchased so far. This is the sad reality of keeping material costs within reason. If you want an extra or a spare now is the time to speak up! I'll be posting the availability of the flanges on a couple of other Opel forums later this week. I am willing to ship overseas.

For those who have stated their interest please send me your area code so I can get working on shipping quotes. I'll give everyone a week to send that to me after which I'll start bugging you about it.

As soon as the first one comes off of the machine and is proven to fit both engines I'll start accepting payment via PayPal or check. Locals can drive down and pick them up (save on shipping).

For anyone who wants to make their own turbo header I'm also making the flanges needed to bolt the manifold to the turbo available. Just keep in mind that these flanges are available from other sources if you don't want to buy them from me.

Rallybob: I'll be sending your mild steel flange back to you with the first stainless flange to come off of the mill. Did you want one or two SS flanges?

[Nathan Acree]

Maybe I missed it but,

Is there a price schedule available? I might be interested in a mild steel (non-turbo) flange.

Thanks,

Zip is 87124

[Geek]

Mark me down for a mild steel turbo header please. Zip is 20104, and I'll send you money for materials as soon as you like.

[RallyBob]

Rallybob: I'll be sending your mild steel flange back to you with the first stainless flange to come off of the mill. Did you want one or two SS flanges?

I'd like two stainless flanges if possible. If you're sending via USPS, then my zip code is 06063. Same address I mailed the flange to: Is that okay to send a check?

Thanks,
Bob

[Gumby]

Maybe I missed it but,

Is there a price schedule available? I might be interested in a mild steel (non-turbo) flange.

Thanks,

Zip is 87124

$40 for a mild steel flange and $80 for 304 stainless.

I'd like two stainless flanges if possible. If you're sending via USPS, then my zip code is 06063. Same address I mailed the flange to: Is that okay to send a check?

Thanks,
Bob

A check is fine. Same address as before. If you need me to resend you my address let me know.

Mark me down for a mild steel turbo header please. Zip is 20104, and I'll send you money for materials as soon as you like.

Got you marked down. The headers are going to be a while yet. I've got to get the flanges made first

[BQS4]

The flanges, be it mild steel or stainless, can be used as a start for either a header, turbo header or possible tubular sprint? Is this correct?

[Gumby]

The flanges, be it mild steel or stainless, can be used as a start for either a header, turbo header or possible tubular sprint? Is this correct?

Correct. You'll just need the flanges to mate the header to the exhaust system or turbo.

[BQS4]

Then I will take one of the stainless flanges. I already have a mild steel one from Bob's earlier batch.

[Gumby]

Then I will take one of the stainless flanges. I already have a mild steel one from Bob's earlier batch.

Got you marked down. What is your zipcode?

[BQS4]

Got you marked down. What is your zipcode?

OOOPS, my bad....30078

[Gumby]

Stainless steel flanges + manifolds are currently spoken for. I was able to get a deal on the metal stock for the flanges so I can't repeat that order with out a lot more interest. Mild steel flanges and turbo manifolds are still open to more orders.