The secret world of the machine shop.
OK here is a rundown on the secret world of the machine shop. I just spent an hour or so here cleaning up some of my parts. Here are some things to keep in mind when talking to, and to looking for one to use. I’m using Rex Hutchison Race Engines.
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Rex Hutchison has been building engines since the flat head was king.
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One of the problems with a shop is the lack of time spent on an engine. When you take an engine to a shop take a look around
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and see just what kind of money is sitting there.
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I mean the type of engines and equipment. Is it just stock blocks or are there a 4 or 5 big money engines there under construction.
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With Rex there are engines that range from stock to 11000 Horse Power costing around $80,000 bucks or more.
What are the steps your engine will go through. First thing that needs to happen after washing
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is to magnaflux every thing. For most places this is a standard practice. The two main types of testing is Dye and Powder.
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Now one big thing the shop must use is an ultra sound thickness gauge. They will need to take at least 2 readings. two measure the bore. Top and bottom.
http://www.mightyram50.net/d-50/rexm...linderwall.jpg
One problem with a block is there is no way to easily measure the wall thickness of a block. Before you bore a block you need to find out how thick the cylinder wall is. If you bore it over .030 you might have too thin of a wall and the engine can crack a cylinder or get hot spots when running. Once you use an ultra sound on the cylinder you can find the thinnest cylinder wall and rough size the bore accordingly. Making sure to have plenty of cylinder wall left.
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Just because a block has never been rebuilt doesn’t ensure that it is a good block.
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Next comes the line bore for the main bearings.
Now comes the wet hone
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Normally they should be done in four steps. (NOTE the next picture has an adapter bolted on to keep the fine hone in line with the bore so you can get the top edge honed correctly.)
http://www.mightyram50.net/d-50/rexm.../fine_hone.jpg
This will put the cool little lines in the cylinder. These lines are very important. With out them the piston rings will never seat and will leak compression gas and oil. These lines must intersect at a 60-degree angle. During this hole process the cylinders must be repeatedly checked for taper and proper bore size. Bore size is determined by the new pistons that are going in and the ultra sound test. Here is one of my new pistons for my V6.
http://www.mightyram50.net/d-50/rexm...TRW_piston.jpg
You must hone out to the final size. This takes quite some time to get it right. Every time you go to a finer stone you must take out less and less material and sneak up on the final bore diameter.
http://www.mightyram50.net/d-50/rexm...king_taper.jpg
Onto the heads. Heads will always be checked for cracks. But if you are going for some power you will need the shop to port the heads. First they CC the combustion chamber then cut the deck or just check for twist depending on what compression ratio you want to get. Then we replace the valves and seats.
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Then we perform a vacuum test to check our work.
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Now they will work on porting and run them on a flow bench.
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So now it’s time to work on the crank. They will polish it if possible,
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if you had spun a bearing or lost oil pressure they must grind down the bad journal.
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Now it can be rechecked for journal run out.
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Last but not least of the fun stuff is the spin balance. In this step we must know a couple of things. First is the weight of connecting rod. This is combined with the weight of the piston and the rings. To simulate the pistons and connecting rods you clamp on these adjustable weights.
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Now we can spin it up to speed.
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During this test we can find out where the heavy spots are. There is a meter on the balancer that shows witch end of the crank is heavy and how high from center is the heavy spot. There is a strobe light that flashes on the crank so you can reference the crank to find the heavy spot to drill.
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We must not forget about the flywheel and pressure plate. If this is out of balance then all the work done on the crank was a waste of time and money. So give them all of your parts.
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One thing that they will do before starting to balance the flywheel and clutch is they should resurface the flywheel. Here is an 11-pound flywheel being ground. The small shiny circle about 1 inch wide is the surface for the clutch.
http://www.mightyram50.net/d-50/rexm...heel_grind.jpg
Well it’s time to put in the cam and start to work on the valve train. One of the biggest things a shade tree mechanic will do is go out and buy the biggest roller rockers they can find then wonder why the engine runs like crap. When setting up the valves you need to get the correct rockers. The rockers must match the cam profile you are using. I just saw a guy bring his car to Rex and asked them to look at it. First thing wrong was the engine had no breather. It was running under a vacuum. Next they has 36 degrees of advance. They put in a cam and rockers on stock compression and heads. I hope this helps to clear up what a machine shop does or does not do.
Welding and my shop area.
I guess it’s time for an update. The temperature is a warm 98 today. So I will just get caught up on the build until it cools off. The main part of the cabin is near complete. I have the seat mounting bars set in place, and the seat belt bars are in. For the guys that want to use a 5-point harness in your truck there are basic things to keep in mind about belts. First use a 3-inch belt. Avoid the 2-inch belt at all cost. They can do more damage to you in an accident then the stock belt. It comes down to simple weight distributions. The more surface the better. A 2-inch belt will bend into taco shape and now you have a ¼ inch rope for a belt. Not a good feeling. This is why they have banned them in nearly all forms of racing. Second DO NOT mount the shoulder belts above the Scapula of your back, Or shoulder blades. If it is to high then you can crack your spinal cord or sever your head during a crash. This would make for a good story on the 5 PM news. Head flies off during roll. Witness says, it looked like he said “holey shit” as it flue over. During a crash you can experience up to 165Gs of force. So keep in mind a seatbelt must not be pinched or have anything that can cut it with in 2 inches of it at all times. You should also think about the direction of forces applied to it. Keep bends and curves flowing not sharp.
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Now here is the main cab structure with some gussets installed. The cross bracing has yet to be installed. So far I have used 60 feet of 1 ½ inch .095-wall tubing and 20 feet of .120 wall tubing just to get this far.
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I have had a couple of people ask what it takes to build a good roll cage. Well here I go.
If you want to build a cage for your truck there is some tools you will need. First is the welder. Go out and find a good 220 Volt mig welder. You can use Argon Co2 mix or just Co2. Don’t use flux core. Straight Argon is for Aluminum I have used Co2 for many years and have just become accustom to how it works. A large tank can last me up to 10 years or more at home. I just replaced one of my tanks after 15 years of use. It went through 5 of the big rolls of .030 wires. Co2 burns hotter than Argon mix and you can burn through thin wall steel. It just takes time to get good. I will get into welding later on.
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Now you need to find a mandrel bender. DO NOT get a pipe bender. There are some ratcheting low cost ones that work OK and make nice bends. You can find them here.
http://www.tubing-benders.com/?gclid...FQ4iawod4Gxx3A
But if you really want to do the job right then you can expect to spend around 1200 bucks for a good quality tool. Here is a good source for tools and lots of other things you will need to do the job. Keep in mind if you buy something good you only need to buy it once. They still make and sell the tools I picked up back in 1997. You can get a low buck tubing notcher.
http://www.irvansmith.com/scart/index.php
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Now when it comes to tools you get what you pay for. I have spent the last 20 years filling up my box. Yard sales, auctions things like that. I set a goal and then collect parts until I have enough to get going on it. Here is my garage and some supplies that people have tossed out that I have found over the years. My nut and bolt collection was a major score.
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Now lets talk a little about welding.
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"When welding tubing you need to keep an eye on the fit of the tubing." If you have a large gap then you will “burn through” You can fill the gap but it takes time and every time you start and stop the fusion of the metal you take a chance of O2 getting into the weld and producing a pimple or “zit hole”. If you have the gas flow up to high wile using Co2 you can over heat the steel. I run around 12 Cubic Inch Hour. At this rate I can get a good Spray of metal. There are times when it can be an advantage to use a Globular transfer method, manley when filling a large gap between to parts. If the gap is large or the parts are thin there is the option to noodle weld.
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Make the fit on your tubing as tight as you can. Spend the extra time and do it right, there is no shortcut in frame building. Remember the forces that will be applied to the cage.
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Let’s talk about getting heads ported. My heads have been ported and are ready to be assembled. You will have many people tell you about valve seats and angles. 1,2, or 3 angle grinds. But when you look to improve performance you only need to look as far as the first 2 inch down the ports. Most improvement to air flow is right below and next to the valve. The head on my engine is within .020 of the intake gasket hole and the intake manifold porthole. When it comes to porting a head you need to open up the area right below the valve seat. The exhaust valve seat and valve has a radius seat. Not an angle cut. This allows for better flow of gas out of the combustion chamber. The intake has a 3-angle grind. This allows for a better seal so combustion gases can’t escape into the intake and cause a backfire.
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One thing I have seen people do is put larger valves in to a head. This can create larger problems and is more costly to do. The only time you need larger valves is if you are building a blown engine or top fuel car. But if you are dead set on larger valves then just go out and pick up heads that are built with them. It will save you in the end. One thing you should do is look to see how close the valve is to the wall of the combustion chamber. On some heads the valve is very close. So by just clearance that area you can greatly improve the flow. Here is a head that has been clearanced to allow for greater flow. It was opened up by .050 that may not seem like a lot but when you deal with 1000s of an inch it is a lot.
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Rear frame is now DONE..........
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