S&S Manifold Length Calculator

Sine, Cosine, Hike!

We know you were day dreaming about sex when the triangles were floating about the blackboard, or for those of you who were already warped, you were doodling motorcycles while the teacher droned on about sines, cosines, tangents. Now all these years later when you finally got the money to build your dream bike by ripping off some other poor fool in the stock market, all you can do is thumb through catalogs hoping to find the right manifold for your V-Twin.

Points in Two Dimensional Space

Well, you can use trig for all sorts of useful pursuits...In this case trying to figure out what TC88 or EVO S&S manifold to order for your bored, stroked and milled big twin. For our RSR Closed Loop Fuel Injection system we modify S&S inlet manifolds for either two or four injector systems and heliarc on a new billet o-ring flange for our 56mm (2 3/16") throttle body. We order S&S Super D large throat manifolds using this calculator and then set them up for turbo or normally aspirated engines. All 113/120/135 ORCA Motors start out with SA inlet castings that we machine and reconfigure.

Sine 22.5 Deg = .382683424 is where it all starts.

Special Application Heads

Big valve S&S Special Application heads like we use in our 113/126/132/139 ORCA Motors have raised ports which effectively raises the inlet casting. If you are using regular S&S Super Stock cylinder heads the port is not raised. We use special order S&S 16-3619 manifolds that we custom order for bore size and specify the length with this calculator.

S&S SA/B1 and S&S SA/B2 heads are different and require different manifolds. Besides changes in valve size they have different bolt patterns and the angle between the ports is different. You can order B2 heads for EVO style single cam engines. We use B2 heads on the 139 ORCAs.

Roll the Dice

Like the man always says...check it twice and check it once again. S&S has had a lot of trouble with people ordering the wrong manifold so they've changed their policies and the part numbers now reflect a specific inch dimension. S&S sells fixtures that you use dial calipers to determine the manifold number to order. You assemble the engine, you buy the fixture, you measure and you order. It's yours to keep.

A stock TC88 manifold is a 410 which equates to 4.100" between some point in space between your inlet ports. All this is supposed to end up with you having a manifold with .015" clearance on each head or a total of .030" to allow for expansion.

S&S makes literally hundreds of combinations as they have different heads, carburetors etc to deal with. 50 years of history to keep track of.

We use this calculator ourselves but use it at your own risk. They make nice paperweights. The S&S SA/B1 manifold pictured below is destined for a 113" ORCA Fuel Injected Turbo. S&S List price before we start our machining is $259.85 OUCH! We're on the wrong side of the counter!

Points of Confusion

When you order a manifold S&S will ask you to call out a center to center dimension of the inlet port. At one time you could call out the short distance between the edges of the inlet port. There is a chance they will machine the manifold and use this number as the distance between the shortest edges of the inlet port or manifold. The manifold they make you will end up a lot longer as the length will not be on the center of the port but the short edge of the port.

S&S has the old number system (7, 8 9 etc) and two other methods....center to center distance and short edge to short edge distance. Take your chances. Throw the hoop over the toy and win a prize.


Your manifold geometry or length is defined by the following five variables which are defined as:

    • Case Height-- Centerline of crankshaft to top of bare engine case bore (no gasket).
    • Base Gasket-- The thickness in inches. TC 88 motors do not use a base gasket. If present typically .020 inches.
    • Cylinder Length-- The distance between the aluminum base and top of the cylinder (no head gasket).
    • Head Gasket-- Thickness of head gasket in inches. Typically .040 inches.
    • Cylinder Head Deck-- Zero (0.00 inches) if the head has not been milled to increase compression.
    • Result Manifold Length-- S&S calls for you to measure your engine before your order a manifold. If you order a specific length it's yours to keep. Clearance should be .015 each side or a total of .030 inches to allow for expansion.
    • Special Application SA/B2 Manifolds-- S&S makes 16-3619 Round Inlet Port Manifolds: 2.250" o.d. and 1.875" i.d.; 16-3629 Oval Port Manifolds; and 16-3629 "Baisley" Manifolds.

Inlet Manifold Length/Number Calculator: S&S Big Twin TC/EVO

Case Height inches Centerline of crankshaft top of engine case. TC88 6.000; EVO 5.375; Special Application EVO cases up to 6.375; Special Application TC88 cases up to 7.125; EVO Sportster 5.375; 113 EVO ORCA 5.875; 139 EVO ORCA 6.375
Base Gasket inches EVO engines .020; TC88 engines do not use base gaskets i.e. 0.00; ORCA motors do not use base gaskets i.e. 0.00
Cylinder Length inches EVO engines stock 5.550; TC88 engines stock 4.937; Stock EVO Sportster 4.650; 113 EVO ORCA 4.995; 132 EVO ORCA 5.178; 139 EVO ORCA 5.178; 126 TC ORCA 4.33325; 139 TC ORCA 4.552
Head Gasket inches EVO and TC88 typically .040; ORCAs do not use head gaskets i.e. 0.00
Cylinder Head Deck inches Un-machined S&S and stock heads 0.00; If you mill the heads to increase compression enter the amount milled. Example: .020
Inlet Port Diameter...round inlet port inches Round inlet ports: Stock Inlets 1.625: S&S Supersport 1.780; S&S SA/B2 1.875
Cylinder Head Type inches Stock and S&S Supersport heads enter 0.00; S&S Special Application B1 (EVO) Heads enter -.550; S&S Special Application B2 (Twin Cam) Heads enter -.480

Note: S&S recommends you measure each engine individually using the measuring fixtures they sell using a dial caliper. If you order a specific length or part number it is yours. Alternatively they can sell you a "long" manifold that you machine to length.
S&S Manifold Number An expression i.e. 410 equals 4.100 inches (TC88 Stock). Center to center inlet ports.


S&S EVO and Twin Cam Manifold Numbers

Engine Application
Old Manifold Size Number
New Manifold Size Number
Stock Height V2 XL 883, 1100, 1200, 79"
91" Sportster

79" Retro Big Twin
100" Sportster
100" Retro Big Twin
89" Sportster
100" V2 Big Twin
88" & 100" V2 Big Twin
111" Super Sidewinder Plus

100" Twin Cam

93" & 113" V2 Big Twin
117" Super Sidewinder Plus

Stock Height V2 Big Twin & Twin Cam
107" Twin Cam

98" Big Twin
124" SSW+ & Twin Cam

103" BT & Sportster V2
116" Twin Cam

139" ORCA V2 (2C heads on V2 SA case)
113" ORCA S&S SA/B1 heads