converting slip joint to flange on side pipes

[olddog]

My headers and side pipes fit together with slip joints. They rattled and leaked. As suggest here I am in the process of converting to flanges.

I made 4 flanges out of 3/8" thick plates. OD of header pipes is 2.005" and OD of side pipes is 2.190." On the side pipes flange, I left 3/16" of meat at the tightest point between the pipes, so there was something to weld to and there will be a seal between the pipes, when I'm done. The pipes were spaced about 1/16" apart before I started. So I did change this spacing.

Now the headers are made with the front two cylinders on one short flange, and the back two cylinders are on a different flange. In other words, the headers are two parts per side.

My plan was to slip the plates on the side pipes. Slip both header halfs into that flange plate. Then slip them together, as they were originally designed. Then I was going to aligne the head flanges to the gasket and clamp to a straight edge. The idea was to get everything aligned up and tack the headers to the flange. Well with the flange plates in place it is difficult to slip it all together, and not possible to pull the head flanges into position to aligne it with the gaskets.


Any body have suggestions on the best way to make sure my side pipes line up correctly after I get it all welded together?

I'm thinking I will have to cut the header tubes off flush to where they would but up to the side pipes rather than slip in. But how do you get the flange plates all perfectly square?