Pipe and header set-up

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MikeConyers

Member
Joined
Feb 23, 2017
Messages
19
Is it better to cut pipe the up to the diameter where slides back and forth on the header or should you just cut the header down to meet the inlet on the pipe?

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Ideally there should be no step between the header and the pipe, and if cut the pipe down so that it slides on the header you've created a step. But I seriously doubt you'll be able to measure the performance difference.
 
Try to keep the header length 2 to 2.5 times the diameter. I prefer to telescope the pipe over the header and sharpen the end of the header to provide a smooth transition on the returning charge from the pipe.
 
I wouldn't cut the pipe. If I'm understanding correctly you are thinking about cutting the pipe where it starts to taper out. The silicone connector would not stay on the taper.
 
I once saw a very custom articulated pipe tied to the throttle. Both the pipe and header were machined with tight tolerances. It was on a rear canard hydro. Very cool.
 
I wouldn't cut the pipe. If I'm understanding correctly you are thinking about cutting the pipe where it starts to taper out. The silicone connector would not stay on the taper.
Exactly! I didn't know if cutting the pipe where it begins to taper out effects back pressure or performance. The way I have it set up now is the pipe is cut to the point where the circumference matches the circumference of the header and then I cut the header down to the desired length. The silicone tubing and zip ties to hold it together.

It seems to me that initially cutting the pipe so that it slides over the header would allow you to test different lengths without ever making a cut again.
 
You don't want the header to stick inside the pipe in the cone area to cause a restriction. On the pipes that have a strait section and it slides over the header nicely just flare the inside of the header ( or chamfer) so it doesn't have a square step or bump. Al Hobbs (AA engines ) has nice 45 and 67 headers for this.

Brad
 
You can also open up the inside diameter of the pipe with a swedge so the header fits inside of the pipe.

Butting a pipe to header usually means you are going to blow a lot of coupler material and of course the stuff always blows out on you at the worst possible time, usually on the bottom where it's hard to see.

When it comes to model race boat mechanics, "if it can go bad, it will go bad". Last weekend I had a carb arm on a CMB 67 come loose. Now I bore out and tap the stock set screw to 8/32 AND bore and tap another hole on the other side the carb arm, use stainless set screws (never use them over) and mount very firmly with Blue Lock-Tite.
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Is it better to cut pipe the up to the diameter where slides back and forth on the header or should you just cut the header down to meet the inlet on the pipe?

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I use a set of Craftsmen 3/8 deep well sockets, most have a gentle slope to help aid in opening the pipe up. Take your time and dont over do it
 
just installed Nova Rossi .21 KEEP outboard i have an Irwin tune pipe what is the best way to to set pipe length and how to measure.
 
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