Custom header parts

[BlownMGB-V8]

You've done some good fitting work there Nick, and at 1" you're probably closer than 95% of the headers made today. Looks like you may have a challenge on a couple of the welds, probably have to take the tube out, weld up the joints and put it back in. I found torch welding to be extremely well suited to building headers, as often I needed little or no filler rod as I went around the joints. Tig would be the same but costlier unless you already have the welder. Some builders like to weld the tube to the open side of the flange and then braze the back side for crack resistance, which is a pretty good practice. Coating the headers is an extremely good idea. Use a first class outfit who can reliably do both inside and out and will stand behind their work and will guarantee it against salt spray. You want it to last and it's worth a little extra.

Jim

[BMC]

I'll second what Tony says. We have had quite a few headers done there and plenty of our powder coating too. Personally, I have only good things to say.

Also, headersbyed- I still have not tried them but believe he is just exceedingly busy. You can find his contact info on this site at the very last paragraph in this article:
http://www.britishv8.org/Articles/MGB-V8-Headers.htm

-BMC.

[Wotland]

Look really great Nicolas.

[NixVegaGT]

Those are your flanges, Dimitri! Sweet.

So far the primaries are 37" long. I could take an inch or so off based on my updated cam choice. What do you guys think? I guess I'll wait to decide until I get the final specs on the cam.

I was thinking about renting time on a TIG welder but maybe I could use my brother's acetylene/O2 torch. I haven't welded with one of those since I was in high school. I remember really liking the control I got from the slower process. Jim, are you saying weld the port side of the flanges and then braze the primary side? I've never brazed before. Any special advice?

I'm definitely taking the pipes off the flanges to finish them up. Do you think I should worry about warping?

Thanks Team.

[BlownMGB-V8]

Nick, you should alternate your welding and check often to control warping, you'll get the hang of it pretty quickly. Correct on the brazing. No real tips, just practice some and make sure everything is clean. I like bare rod and can flux for more control of the amount of flux and fill but that's just me. It's like soldering, get the base metal hot enough to melt the rod and make sure it wets properly. On your collector length, the advice I've heard was to run up the engine before coating the headers and look for a band of heat discoloration on the collector  and that's where you cut it because that's the end of the standing wave. Maybe so, I took it all the way to the glass packs at that size. As far as the primaries, the longer they are the more they shift the powerband down, and that's played off against the diameter which shifts it up as diameter increases. What is your cruising rpm? I'd put that dead in the center and then adjust upwards for redline. If you tighten up on the diameter the length should decrease and vice-versa.

Jim

[NixVegaGT]

OK I finally finished mocking up both sides now. It was actually a little tougher on the right side. I had to run the tubes over the starter and that constrained things a little. I also had to turn them to clear the heater box. I ended up putting the rear tube over the third tube near the flange and down the middle to meet up with the first and second tube to run back. This caused it to be a bit longer. Here's a pic showing the end.



In this picture I've used the same romex wire I've been using for length. You can see that the previously mentioned tube is almost 2" longer. I'm a little bummed about that. Do you guys think this will be a problem? Also now that I have the final specs for the cam do you think I should make the overall length shorter?



Here's the final pix:

[BlownMGB-V8]

It looks pretty good Nick. I wouldn't worry too much about that 2". Ed told me one time that about 90% of the headers made had worse mismatches than that so about the only thing getting closer than that buys you would be bragging rights. You've got a fine looking set of headers there.

Jim

[Dan Jones]

> In this picture I've used the same romex wire I've been using for length.
> You can see that the previously mentioned tube is almost 2" longer. I'm a
> little bummed about that. Do you guys think this will be a problem?

Vizard has tested headers for primary length variations and says that while
180 degree headers are sensitive to a few inches of variation bank separated
4-into-1 headers are not very sensitive.  Vizard also says that in his
testing average primary lengths between 24 to 36 inches yield similar results
(area under the curve) for bank separated 4-into-1 headers.  At 37" inches,
you're a little on the long side.  You might want to trim an inch or two.
Collector lengths between 12 and 20 inches should be goood to 8000 RPM.
In testing on small block Ford Windsors (small port and valve like the
Rover/Buick), 9 out of 10 times longer collector length, up to 25 inches,
will translate into increased performance regardless of cam or RPM.
If the choice comes down to lengthening the primary or lengthening the
collector, go with the longer collector.  There will typically be a
noticeable burn pattern inside the collector which will indicate the length
the engine wants (once the engine is properly tuned for fuel and spark).
In my own testing, the mufflers were even more important than collector
length.  We've lost as much as 50 HP through mufflers.  Straight through
designs like the Magnaflow were nearly as good as open pipes.

Dan Jones

[NixVegaGT]

What about distance to the x-pipe? Is this part of "Collector" length on a full exhaust system?