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http://www.artsautomotive.com/machineservices.htm

 

Art's Automotive Machine Shop Services

page under construction

Valve Seat grinding:

We charge 0.25 labor hours to grind each valve seat. The valve seats are steel inserts pressed into the aluminum head. The seat to valve contact angle is cut to 45 degrees. The width and contact position on the valve are usually adjusted with a 60 degree "throat" cutter and a 30 degree "top" cutter. Some cars use different angles; we always follow the manufacturer's original specs when grinding the seats. The attention given to getting the seat cut to match the manufacturer's specifications exactly will have a direct effect on how long the rebuild will last. Our machinist, Sandor, has the necessary experience and the commitment to quality to ensure your rebuilt head will perform the same as it did when it was new.

Valve Grinding:

We charge 0.1 labor hour to grind a valve. Most new valves cost between $15 and $35 each. On a 16 valve head, grinding instead of replacing could save you as much as $475. It still makes sense to grind whenever possible. Many valves found in newer cars are tiny, and don't have much of a margin. We only grind valves when the manufacturer says it's an acceptable procedure and we always thoroughly inspect the valve for wear before machining and maintain the manufacturers minimum margin specification. For those of you looking at the picture and thinking, "Wow, that looks like an old valve grinder!", you're right. But old does not equal bad. This is a very well built Snap On unit and works as well today as it did when it was new. We also have reducing collets and can machine valves with stems as thin as 4mm.

Cylinder head milling

This is a Kwik-Way 855-5 head surfacer I put about 40 hours into restoring and converting to a mill. The ways were remachined at Worrell Industries right here in Berkeley and the grinding stone was replaced with a Jamison milling head. The traverse motor was replaced with a DC speed controlled motor, to slow the feed rate down to a barely perceptible creep. This machine now produces a *very* smooth 15 RA finish on aluminum heads using a CBN insert & WD40 as lubricant. Hasselgren Racing did the surface roughness testing since they are the only machine shop in the area who own a prolifometer. We might be able to get an even smoother finish with a PCD insert and specialty aluminum cutting oil, since we've found another shop with a converted grinder claiming a 7 RA finish using the same Jamison milling head conversion with PCD inserts. However, 15 RA is 5 RA better than the lowest surface finish spec we've encountered for engines with MLS gaskets so far.

Cylinder head resurfacing

We use a platen grinder surfacer for cylinder heads. It uses an 80 grit Silicon-Carbide belt to grind the cylinder flat. Since this is a "dry" machine with no circulating coolant / lubricant, we coat the belt with Goodson's Grind Aid. This has improved the surface finish we obtain. This type of surfacing is all most heads need. However, some applications use MLS (Multi-Layered-Steel) gaskets which require a very smooth surface finish. For those heads we follow platen grinding with lapping to obtain a surface as smooth as original. Some heads, like V6 heads with an angled intake manifold sealing surface, need to be milled instead of ground. We do not do in-house milling, so if your head needs milling, we will sublet the surfacing to a machine shop we trust.

Cylinder head Lapping

We charge 0.5 labor hour to lap a cylinder head following surfacing. Engines with MLS gaskets require very low RMS finishes to seal properly. Since 80 grit is the finest belt currently made for platen grinders, we use a granite surface plate (a precision machined slab of granite, ground to .00001" of perfectly flat, originally intended as a base for measuring). We smear some lapping compound on the plate and then slide the cylinder head in a figure eight pattern until the surface finish is very smooth. We were originally concerned that this technique would create a convex surface on the cylinder head. However, we've found no measurable change in the flatness of the cylinder heads we've done so far and no measurable wear is evident on the plate itself. This technique is physically tiring, but produces a beautiful finish.

Valve guide replacement:

We charge $20.50 to replace each valve guide + the cost of the part. If the valve guide to valve stem clearance is excessive it causes two problems: one, the valve seat can not be cut concentric and two, the engine will consume more oil than necessary. The condition of the valve guides can not be known until cylinder head is out of the car and the guides are measured. This means when we find worn guides, we need to call you for additional authorization to replace the guides. Worn exhaust guides are more common than worn intake guides because the exhaust valves get much hotter than the intakes. To remove the guides, we heat the head to 200 degrees (F), then we drive the guides out with a driver powered by a pneumatic hammer. To install the guides, we reheat and chill the valve guides before driving them back in.

Valve guide reaming:

This is included with the price of valve guide replacement. The new valve guide must be sized to obtain the manufacturer's specified oil clearance. This is done by measuring the valve stem, adding the oil clearance spec., and using a sized reamer to cut the guide to size.

Penetrant Dye Crack Checking

We charge $82 for penetrant dye crack checking a cylinder head. This includes hot tanking and cleaning the cylinder head prior to the check. The first step is to clean the cylinder head. Care must be taken to prevent covering cracks by wire brushing. Aluminum is a fairly soft metal and a vigorous brushing can actually cover cracks, making them undetectable with dye. Next a penetrating dye is sprayed on the area to be checked and allowed to soak in for 5 minutes or so. After soaking all of the dye is wiped off using shop towels. Once the head is cleaned, a developer is sprayed on. Cracks will show up as red lines. Just going though the motions of a penetrant dye test does not guarantee you'll find a crack. The key to success is very careful inspection. The dye is just a tool that makes finding cracks a little easier. The real way cracks are found is through the thoroughness and experience of the person doing the test, not the test itself.

Cylinder Head Pressure Testing

Pressure testing is the best method of testing for cracks because cracks in areas that are not visible can still be found, areas like under the valve seat or half way down a head bolt hole. This is an Axe pressure tester we purchased used. It does not require a special plate set for each new head. It uses 20 universal deck plates and universal port block off plates in various sizes. It covers 95% percent of all heads and 100% of the heads we repair here at Art's. To check for cracks, we block all of the cooling system ports, then we pressurize the water jacket to 40 PSI (about 3 times normal cooling system pressure). We then submerge the head in heated water to bring the head up to its normal operating temperature, and to make leaks easier to spot by following the bubble trail.

Flywheel Grinding:

Art bought this flywheel grinder in the 1990's, and it's more than paid for itself. Buying an expensive single use machine can be a little risky for an independent shop. However, the being able to continently machine the flywheel on every clutch job has allowed us to offer a better quality clutch job in a single day without driving to and from the machine shop and worrying about whether the machinist will get the flywheel done in time.

We have just switched from silicon carbide stones to diamond cutters and we're very pleased with the results. The diamond cutting wheel cuts flywheels much faster and leaves an attractive sharp step on the flywheel and a very nice finish.

Brake Rotor and drum resurfacing

We offer 3 welding processes:

Oxy / Acetylene - which we mainly use for heating, stress relieving, and cutting.

GTAW (TIG) - which we use for aluminum, or when a more attractive weld is needed, or when welding very delicate parts.

GMAW - which we use for welding steel. It's the easiest and fastest process and produces smaller more attractive beads than Oxy Acetylene.

Welding repair can save a lot of money over buying new parts, and in some cases, the part's strength can be increased over the original. We now own a Lincoln Electric Precision TIG 375 soon, and are offering more aluminum welding, including cylinder head repair.

 
This is a picture of the flex joint we welded into the catalytic converter of a 49 State Camry. The old flex joint had cracked and was leaking. A new converter cost $1100, just for the part! Since the rest of the pipe was in relatively good condition, we were able to weld in an aftermarket flex joint for about a third the cost of just the new part. We used the TIG welder for this job since this area of the exhaust is highly stress and we wanted to be sure our work held up over time. The TIG welder uses a high frequency pulse to start the arc and can sometimes damage sensitive electronic equipment (although it is very rare). Since this car is loaded with electronic control units, we tacked the flex joint in position with the MIG, then did the TIG welding off the car.
This is a cast iron exhaust manifold that had cracked in several places. I use the TIG welder and pure nickel filler rod to weld cast iron. Cast iron is a difficult material to weld because it is very rigid and will crack rather than bend. When it is melted (as it is when welding) it will expand. When it cools and contracts, it will crack in areas adjacent to the weld. The solution is to preheat the entire casting slowly and evenly, weld, then allow the casting to cool slowly and evenly. Unfortunately our oven does not get hot enough for proper cast iron preheat, so my experiences welding cast iron have been mixed. I tend to have far better luck with welds on an edge or corner of a casting, rather than in the center.

 

Plastic welding

Plastic welding is *real* welding. It's not like epoxy, crazy glue, or a hot glue gun. The parts to be joined are heated until they melt (about 450 degrees, depending on the type of plastic) with a hot air torch. Plastic filler rod made from the same type of plastic as the base material is melted into the joint. The result is a part that is about 90% as strong as the original part if machined to the original dimensions, or potentially stronger if the part is built up or reinforced. Not all things that look like plastic are plastic though. Fiberglass, Bakolite, some glass impregnated nylons, and some blends are unweldable. A product called Fiber Flex can be used to braze some non-weldable plastic or plastic-like parts. However, a brazed part will not be as strong as a welded part.

This is a driver's door master switch cover. That has been discontinued.

This is a broken plastic lug on the underside of the cover that holds the switch to the cover. Without the lug, the switch falls into the door panel.

The first step in plastic welding is to determine what type of plastic the part is made from: PE, PP, ABS, PVC, HDPE, Nylon, etc.. The easiest way is to find a mark or recycling symbol on the part. If there is no mark, attempt to weld each type of rod to the part until one sticks and won't pull off. This part is ABS.

Next I grind down the remaining part of the lug with a wide flute carbide die grinder bit, leaving a flat surface. Once the surface is prepped I add plastic filler in small coils, cooling the plastic with water after each coil. This solidifies the plastic already deposited, making it easier to build on.

Now the rough shape of the lug has been built.

With some careful die grinding, the lug is returned to its original size.

There was also a crack underneath the lug. The crack is ground out (just as you would when welding metal), then groove is filled. On this job I ground extra deep to reach the center of the lug on the other side. This will make sure the lug is well attached.

Now that all the cracks and damage have been repaired, and new screw holes drilled and tapped, the part is ready for re-assembly.

 

I

It's ready to be put back into service. Since all of the damage was in non visible areas, it looks as good as new.

Spray cabinet washing
Pressing operations

This next list contains machine shop operations that we outsource. All of these operations are better performed by those willing to invest in the specialized equipment necessary to do the job properly.

 

Block decking

Connecting rod servicing

Crankshaft grinding

Cylinder boring and honing

Align boring

Cylinder head straightening

 

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