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assembling a WELD-ON cone engineering conical MERGE COLLECTOR

Begin by assembling the merge bullets.  The top left photo shows what one set of bullets looks like.  Start by standing them together as shown in the top right photo and slip the round assembly tool over the top as seen in the bottom left photo.  The notches in the tool should line up with the sides of the merge bullet


Now you’re ready to tack-weld the bullets as shown in this next group of photos. 

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Remove the assembly tool and make your finish welds.

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After welding, a little cleanup should be done to optimize air flow.


Here is a comparison of  what the welded merge bullets look like before and after cleanup.

Now that we’ve finished the prefabrication, let’s finish up the headers. The primary tubes need to be square and flat before the merge bullets and collectors can be welded into place. To keep the tubes aligned and square, we created a series of jigs that slide over the primaries: Weld-On Collector Header Tube Alignment Tool. click here >>

To start your collector fabrication, just slip the jig over the primary tube as you see below. You can do this without the jig, using clamps and a square, but the jig makes it easier and faster. The jigs are also reusable; they’re great for building slip fit collectors and can also be used to assist in designing and fabricating the header primaries while in the vehicle or on an engine stand.


You have the tubes nice and square so now they can be tack-welded together.  We do this before grinding them flat so that they stay in position while grinding.  Place your tacks in the center of the primaries to make it easier to slip the jig off.  Nice light tacks will do, since it’s just to get through this next couple of steps where the real strength will be added.  Once you’ve made your tack welds make sure the primaries are flat and square.  A square or even a flat table helps make sure you did a good job grinding the primaries.

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Once you have confirmed that the primaries are flat and square, the bullets can be welded into place.  In the first photo, the previously assembled merge bullet has been aligned and tacked into place.  Our merge bullets are designed to the specific tube diameter so that you will get a nicely matched joint.  You’ll generally want to make your welds on opposite sides to help compensate for material shrinkage.  In the second photo you can see a finished weld as he is working on the last port. 

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Here you can see the welds being cleaned up and blended.


Our next step is to slip the collector over the primaries to make sure we have a good fit.  The first photo gives you a good look inside the collector to see how it all fits together.  If you have any large gaps you can use clamps and some metal wedges to pull the collector down closer to where you will be welding them to the primaries.  The second photo shows you another great trick - drop a small bead of weld into the area shown being cleaned.  Doing this before welding on the collector is a lot easier than after you have tacked it into place! 

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We’re entering the home stretch!  Now we take our collector and slip it over the merge bullet onto the primaries. Since we had already laid a little filler under the corners in the last section, we are ready to tack the collector into place and make our finish welds.


There it is!  The finished header with the collector installed!  On this particular build you can see that we also added a transition cone to help increase exhaust gas velocity.  We had also added a 3-bolt flange to mount up to our exhaust system. 

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