Testing home built headers for leaks

[WSSix]

Now that I am in the process of making my own headers, it has me thinking of what I can or need to do to test the headers for leaks. I plan to coat the headers once finished. The last thing I want to do is cut up freshly coated headers. Anyone have some suggestions on ways I can test for leaks? I'd like to actually drive the car around a bit before coating them so I can verify that my clearances with the body etc, which are tight, are good enough. Will this affect the coating process later? I'm hoping I can just have the headers cleaned and sand blasted to get them back to a point where they can be coated correctly.

Thanks

[69hugger]

I would think you could fairly easily make a system to pressurize the tubes. use a flat plate over the head flange & make or buy a collector flat plate. Drill a hole in the collector plate & install a pressure valve (maybe just a rubber tire valve). Hit it with 20 or so psi & see if it holds pressure. Might have to use gaskets or silicone to get a seal. You can always spray soapy water to find pinhole leaks.
A bit of a hassle, but as you said, good to check them before coating.

Good luck!

Bill

[Che70velle]

Trey, once the headers are built, I'd bolt them to a spare cylinder head, with a good gasket. The head must have exhaust valves and springs installed. You can also use a block off plate, designed to close up the exhaust ports of a cylinder head during storage, or shipping, but it's more probable that you have a set of heads lying around. If you don't, then you can make the block off plate yourself.
Cut up a piece of innertube, or similar material, and stretch it across the collector side, and well up the collector, then use a 3" hose clamp and snug it around the innertube on the collector. This will seal both ends.
Attach a pressure gauge using store bought fittings, to the o2 port, and put 10-15 lbs. on it, and monitor.
If you don't have an o2 port, you can integrate a threaded port onto your block off plate, on a tube.
Whatever you do, DO NOT use water inside the headers! Rust inside a header KILLS performance.
Coating used headers is no problem. The coater that you use will sandblast them before coating anyway. Lots of guys have headers re-coated many times.
Hope this helps...

[WSSix]

Thanks for the responses, Bill and Scott. Those are good ideas. I do have a second set of LT1 cylinder heads that are assembled. I think I'll definitely incorporate them so I can also check the flange's flatness.

Thanks

[parsonsj]

I pressure test headers as I go. Check each tube as you finish weld (use the same parts you use to back-purge the welds).

If you wait and pressure test when you're done, you may find a leak in a spot you can't reach with your welder.

When the heads are done, just clamp them to a flat surface and use compressed air to provide 5-20 psi. Again, just use the adapters you used for back-purging the welds. Even 2psi will be adequate for finding leaks.

Soapy water will find any leaks even if you can't achieve a tight seal on your test scaffolding.

[WSSix]

Thanks John. That's a good idea, too. I appreciate the feedback.

[MeanMike]

Are you mig or tig welding them? I've never pressure checked mine, but I tig weld them and it's easy to spot a hole. The collectors are the hard part, but if you follow the right process for the style of collector they are easy to keep leak free.

[IMPALA MAN]

1. Install a pipe plug like this in the collector
http://www.newmantools.com/petp/143_2.htm

2. Make a plate to bolt the header flange to.

3. Drill and tap a hole in the plate to install one of these
http://www.timsautosupply.com/shop/d...lugs-14-in-npt
Or one that matches your air hose.

4. DO NOT USE LINE PRESSURE. 10 psi is more than enough. Typical pressure inside a header in use is very rarely over 3 psi in extreme cases.

Whatever you do, DO NOT stand in the way of the rubber plug and do yourself a favor and point it towards the ground.
We are not trying to make a potato gun here, if you know what I mean.

[WSSix]

Mike, I'm MIG welding the headers. I went with parts from Cone Eng so the collector fits tightly over the primaries. I also will have merge bullets on the ends of the primaries.

Thanks for the links Impala.

Thanks