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Question: I am looking for a quality set of exhaust manifold gaskets for the 345 engine in my IH scout. I have tried several different brands and they all leak. OK, I have headers on it of an unknown make, and everyone tells me that header gaskets always leak. I really don't want to get rid of my headers.
Answer: The first thing to do is take the headers off and put a straight edge across the flange. You want to make sure that the sealing area is flat and true. I can tell you right now it's not going to be, but what you're looking for are high and low spots on the flange. If you're careful, these can be ground out with a flat belt sander. If they are warped upward at the ends, you're in for a bit of work.
What I have done in the past is clamp them down to my welding table by the ends and place some 1/4-inch flat stock across the center two outlets. This way, you're forcing the header flange to bend in the opposite direction. It will most likely take a bit of discretionary heat in the proper places to get it to bend. There is a lot of guesswork here as to how much to bend in the opposite direction as there will be some movement back.
Let's assume that you got the flange pretty darn close to being true. Now for a gasket: There are a lot of different gaskets that claim to be leak-proof, but I have been impressed by those from a company called Remflex (360/492-3100, www.remflex.com). These gaskets are made from flexible graphite and have a 50 percent crush value to handle any imperfections in the flanges. Well, maybe not any, but they do a good job of sealing. They even make them for IH motors under PN RF5001, and the cost is about $32. Yep, that seems like a lot of money for a set of gaskets, but maybe not so much if you have already replaced them several times.
Question: Can you guys explain how a stall converter works? I've heard of people using them and I want to know how they work, and why people choose to use them.
Answer: All torque converters slip to some extent, even when they reach their "stall speed." Stall speed, in theory, is when the driven part of the torque converter is rotating at or close to the same speed as the driving part. The fluid movement "stalls" and no slippage occurs. Most late-model vehicles have what is referred to as a lockup feature that mechanically locks the converter so no slippage takes place when the ECM (computer) determines certain conditions exist, and usually only in high gear.
It's not recommended to do, but if you put your vehicle up against an immovable object, shifted to low gear, and floored the throttle, the stall speed of the converter would be the maximum rpm the engine could reach. Most passenger car and truck converters "stall" in the 2,000-rpm range.
The stall in a converter is often used as a tool to allow an engine to reach its maximum performance. For instance, if a race motor idles at 2,000 rpm and makes its power from 3,500 rpm and up, then a converter that stalls in the 3,000- to 3,500-rpm range would be used. In fact, even if the engine made good low-rpm power, a higher stall-speed converter, combined with the right axle ratio, may gain better dragstrip performance, but the converter may not reach stall while driving down the highway. Do keep in mind that the more slippage, the more heat is developed.
Picking the proper stall-speed converter is pretty tricky and best left to those companies that build them. They take into account the axle ratio, tire size, vehicle weight, transmission used, engine cubic inches, fuel delivery system, camshaft specifications, and most important of all, vehicle use.
Question: I have an '01 Super Duty with the 7.3L diesel. I seem to have an oil leak at the rear of the engine. My mechanic said that it was coming from the oil-pan gasket, which he changed-but I still have the leak. It did seem to go away for awhile, but now it is back. He now thinks that it's the rear main seal that's leaking. He says that there is a lot of labor involved in this and it will be expensive. Would I be better off selling the truck and buying something with fewer miles on it? The truck now has 171,000 miles.
Answer: Yes, replacing the rear main seal does involve a lot of work. Sell this truck and buy a new truck? Only you can answer that question, as a lot has to do with how much you like this truck, and its overall condition.
Then again, you may not have to sell it. There is a pretty good chance that the oil may be coming from the high-pressure oil-pump outlet fitting or maybe the end plug. It then can run down the back of the engine, which will mimic an oil pan or crankshaft seal leak. I would clean everything up and then start watching to see where the oil actually comes from. This is a repair that you might want to delegate to your local Ford dealership.
Question: I have a Ford F-150 with the 5.4L V-8 engine. So far, I have added headers and an after-cat exhaust system to it. I still want more power. What else can I do to make more horsepower without putting out a bunch of money? When I went to 35-inch tires, I really lost a lot of power. It seems that I have to drop a gear lower than I used to when pulling any kind of a grade with my boat trailer behind me.
San Francisco, CA
Answer: I think you figured out where the power went. The taller tires raised the overall gearing and put the engine speed below the rpm where engineers designed it to work best in.
Your best bet would be to swap in some lower gears in the 4.10:1 to 4.56:1 range. OK, that's expensive and a lot of work, so be content with just shifting the trans to a lower gear.
Edelbrock (310/781-2222, www.edelbrock.com) has recently released a larger throttle body for the '91-'03 Ford 4.6L and 5.4L V-8s. Best of all, each model is CARB-approved and is 50-state emissions-legal. While it won't gain back what you lost in tire height/gearing, it will make a performance difference.