Exhaust Primary Tube Header Length...


Active Member
Sep 3, 2018
Monrovia, California
How long should the primaries be on Long Tube Headers? Well, the simple answer is not too short and not too long. Somewhere between 30-inches and maybe 33-inches seems to kind of be the standard. The funny thing is that if they are shorter than that it really doesn't seem to hurt power at all. The only thing about making the primaries shorter than that is that you can no longer call them Long Tube Headers. And so what? When we started building headers, there was no such thing as Long Tube Headers, they just called them "tubular headers". I can't actually remember when the name "Long Tube Headers" first started. Probably when the original Mustang 5.0 headers were introduced, and people started referring to them as "shorty headers". At any rate, Long Tube Headers is what people ask for and that's what we offer for the early Mustangs (1965-1971) as well as the later Mustangs (1979-1995). On the early Mustangs, depending on the year of the car and the deck height of the engine (8.2-inch or 9.5-inch), we offer Long Tube Headers with 1 5/8-inch up to 2-inch primaries, for pretty much any cylinder head you can think of. Are they equal length primaries? Nope. They are as close as we can get to being equal length considering the tight engine compartments, but they are not equal. Nobody can build equal length header to fit into stock chassis. The good news is that it really is not very critical if the primaries are equal length. It's a myth.

This is about as close aw we can get.


If we had all the room in the world under the hood of a Mustang to build headers like this, we could do it, but that is just not the case. Actually, these headers are probably not perfectly equal either. But again, so what? It really is just not that critical. And even if they were equal length, the length is only "perfect" for what RPM? 6000 RPM? 6800 RPM? 7500 RPM? 5000 RPM? Pick one because the "perfect" length is only "perfect for one specific RPM, and is either too short or two long for any other RPM. But, and this is a BIG but, we do not run our engine at only one RPM. We want good performance maybe starting at 3000 RPM all the way up to maybe 6500 RPM, and there is NO "perfect" length for an RPM spread like that. And so, we compromise. By the way, the same holds true for intake manifold runner length. It's not always easy to have equal runner length on intake manifolds, either, and even if we could, what is the "perfect" runner length? Same issue as with headers, there is no "perfect runner length" for all RPM's, only one specific RPM. In the 1970's, when the Can Am sports cars were a big deal, the McLaren's were the hot set up.

They were powered by fuel injected Big Block Chevy engines.

The runners are NOT equal length, on purpose. Sports Car racing engines are constantly going up and down on RPM, going into turns, coming out of turns, straight aways, etc., with the driver shifting up and down dozens of times every lap. The McLaren engineers figured out that the only way they could get the "perfect" runner length, was to compromise and make four runners too long and four runners too short, and somewhere in the middle was the "perfect" length.

Anyway, if you are looking for good fitting high performance headers at a fair price, give us a call at (909) 552-3690. Every header is built one at a time specifically for the customer's car / engine / transmission combination.

George Klass - RCI Custom Headers
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I don't dare do that to my Knob
10 Year Member
Dec 30, 2002
Cornwall, PA
I'll be looking you guys up in the next couple months for a set of headers for my 363 / C4 combo. Really like the look of your mid-length headers as I'm trying to get away from long tubes.


New Member
Oct 2, 2003
Pensacola Florida
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I will be needing a set for a 69 Mustang with MR heads same as CJ heads. Large displacement ~511 so probably want 2/2 1/8" primaries. Is it possible to place all four tubes behind the shock tower or do the forward tubes have to go under the lower A arm?


Active Member
Sep 3, 2018
Monrovia, California
I wondered about that. The answer is yes, we can do that header on that year Mustang, and that combination. And yes, the front primaries do need to go under the front suspension...


Active Member
Sep 3, 2018
Monrovia, California
Let's discuss this on Monday. Give me a call at (909) 552-3690. Have you checked out our website? www.rciheaders.com

The 2 1/8" FE Long Tube Headers require a Slip-On Collector. The standard header with the 3 1/2" Collector is $1,049. If you would rather have a 4" collector, the price is $1,089. Our flanges are 5/16" thick. On this particular header, we use a "step header" design, in which the first few inches of the primary are 2" diameter, stepped to 2 1/8" for the rest of the primaries. We have found in testing that this ads additional mid-range torque without hurting top end power...

George Klass
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