Why is the intake runner so darn long??

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drzomber
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Why is the intake runner so darn long??

Post by drzomber » Sun Mar 16, 2025 10:09 pm

I'm new to T's (I have had a bunch of A's in the past) and don't understand why they make the intake runner so long. Even on aftermarket intakes (except for the Winfield) it seems excessive. I guess I could understand it if they were building a high revving engine but given the application it seems really odd to me. Can someone explain the reasoning to me??

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Ed Baudoux
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Re: Why is the intake runner so darn long??

Post by Ed Baudoux » Sun Mar 16, 2025 10:20 pm

I believe that the length of the intake drop is intended to allow enough drop for the gravity fuel system. Some earlier body styles had a longer drop.
Grayling Michigan
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Tadpole
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Re: Why is the intake runner so darn long??

Post by Tadpole » Mon Mar 17, 2025 8:25 am

If you think Ford was bad, look at Chevrolet’s!
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TXGOAT2
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Re: Why is the intake runner so darn long??

Post by TXGOAT2 » Mon Mar 17, 2025 9:22 am

Longer, small bore intake manifolds work very well on low speed engines with mild cam profiles. Short, large bore intake runners with no manifold heat would give very poor results on a stock Model T engine, especially with the gasoline commonly available in the 1920s. An intake manifold can be "tuned", much as an exhaust header can be "tuned". Modified T engines that run at higher speeds with high lift, long duration camshafts and larger carburetors can take advantage of shorter, larger-bore intake runners.


Erik Johnson
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Re: Why is the intake runner so darn long??

Post by Erik Johnson » Mon Mar 17, 2025 7:38 pm

As Ed posted above, the gravity flow fuel system is the reason the carburetor sits so low and the intake is so long.

My father's 1910 IHC Model F roadster has overhead valves and has a much longer intake than a Model T Ford.


got10carz
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Re: Why is the intake runner so darn long??

Post by got10carz » Mon Mar 17, 2025 8:13 pm

Here's my theory. The firing order is wrong. The model T is 1243 as are most early 4 cylinder cars. This requires the front 2 cylinders and rear 2 cylinders to suck 1 right after another. The long manifold has more fuel stored in the manifold. A better firing order would be 1324.

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Craig Leach
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Re: Why is the intake runner so darn long??

Post by Craig Leach » Mon Mar 17, 2025 9:52 pm

The firing order on a T does as I understand causes a flow issue that would be rectified with a 1423 or 1324 configuration. Reversing the ports
has been tried with some success as I understand. Now that cams are being manufactured again maybe someone will bump the program & make
some. Kirk Wright built a 6 cylinder out of T engines & somewhere there are pics of him making the crank & cam. A stock came could be cut up
& put together to do this also. Didn't Winfield's 2up 2down engine have a modified firing order?
Craig.

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