Vertical exhaust

It has not been tested in combat yet but should work and also allows me to simply unscrew the muffler section from the coupler and remove the hood when needed.

The ram tuning only works within a narrow RPM range.
Also you'll want a relatively freeflowing exhaust with individual pipes going to each cylinder. The idea is to time the "reflected" pressure wave from an exhaust pulse with the opening of the exhaust valve so that negative pressure exists at the exhaust valve as it is begining to open. As rpm changes, so does the timing of the pulses and at some point you have positive pressure and inhibited exhaust flow. I guess if you could invent an exhaust pipe that changes length with RPM you could make it work over a wider range!

With a typical cast iron manifold that dumps all the cylinder more or less into a "log", the ram tuning effect is basically lost.

I haven't really paid attention to the manifold on an F-12, I'll have to notice next time I see one.

Your not going to hurt anything by cutting 3" off the top of that mufler. I've had 8" off my SA for years, mainly to keep it from catching trees when mowing. Just use a hack saw and smooth it with a grinder afterwards. If it's just a matter of getting through the shed door, throw the damn rain cap away, that will give you 3" extra clearence, and the 3" of pipe will do you more good than the rain cap. One thing I don't like with my SA with pipe cut off, if wind is right direction, it blows fumes in one's face. Without the raincap very little of that oil mist will hit your paint job. If the tractor is just going to sit out one night overnight it wont take on enough water to fill a thimble even in a 3" rain fall, providing there is not a high building or tree deflecting water down the stack. If it's going to sit out long term, soup can is the best raincap. I've seen those raincaps up in rain and wind, and actually deflecting water down the stack.

I've also seen raincaps catch on tree limbs and break the manifold or exhaust pipe on small tractors. They do last quite well on a diesel, however gassers burn rain caps up in 600 hours. Just a waste on money in my opinion.

This is what Gene is talking about, I just picked
up the elbow at my local auto parts store.

Gene's got a B out there in Iowa with 16" rear tires. I tell Gene, I'm going to take my Woods and a V6 buick engine I have here and build my own zero turn. There is a guy in Newfoundland, claims he has a 454 Chevy 4 barrel in his ride on mower.

I believe there are two factors at work here, fist being few rain gauges are 6' - 9' off the ground, secondly wind hitting the tractor creates an up draft causing much of water to blow right over the tractor. So many people park their tractor in the shelter of a building or a tree, that will put water down a stack probably twice the rain fall. Another bad one is the rain cap blown open by wind, deflecting water right down the stack. The very worst is an exhaust pipe or manifold leak, those catch much of the rain that hits the hood.

In contrast, I got caught once 300 and 560 both on flood plain, neither pipe was covered. It rained 9" in 24 hours. Flood waters came up, however trctors were on a high knoll, drawbar deep in water and we couldn't get to them other than by boat for 3 days. Didn't even try as the ground around them would have been soft from all the rain. On the 4th day We got out there, started them, they blew a bit of black soot, definitely nothing in the cylinders.

This is what sparked the debate at our farm on just how much water actually get down a stack, and what conditions make it worse. My dad argued that with tight exhaust in a an open field situation, very little water will get in the tractor. There were about 6 of us in that discussion. A few weeks later dad came in the barn one morning after a rain. He had a condom in his hand, course everyone got on his case as why a 60 year old would need that. However this was his proof on water down the stack, he had placed this in the stack of the 130 before the rain. There was water in it, but certainly no where near the rainfall we had. He had checked the rain gauge and figured about 10% got down the stack.