ENGINES DONE RIGHT  

THE CMRE WAY

Engines arrive at CMRE by air freight or truck. Each engine is then disassembled carefully, paying close attention for any signs that might show problems that would need to be dealt with to make the end product superior. If an engine comes in broken we want to know what broke and why it broke so that we can improve that component.  Engine disassembly is never taken lightly at CMRE.                                                                                                                        

The next step is cleaning and inspection. Blocks and their related components will usually spend three or four days in a cleaning vat @ 180 degrees and then are pressure washed. Even though it is more work for us we feel that the hot vat method does a better job on blocks cleaning the oil galleys. Blocks are then pressure tested to make sure there are no hidden cracks. All cylinder heads receive this cleaning and pressure testing, even new ones. Line bore and cam bores are also checked at this time.                                                           

The next order of business is checking the block's deck heights and milling them square with the crankshaft centerline. We do this operation on a Winona VN 2000 vertical milling machine that uses a bar that the main saddles set on as a register to align the deck with the crankshaft centerline. At this time our main objective is to get the deck square so that we can reference off it to bore our cylinders. The engine block is then bored to within .005 of it's final bore dimension.

Cylinder honing. The block now goes into our custom built power hone and gets it's head bolt holes thread chased. Next one of our many BHJ race model honing plates with a head gasket that is the same as the one to be used on the finished engine is installed. Bolts are torqued in the same sequence and to the proper torque as they will be in final assembly. Blocks are rough honed .002 with a 70 grit Sunnen stone set, .0015 more with the next stone set, and.0015 with a finer stone set. Next a special stone set is used to give the final plateau finish that is free of folded, tom material and burnishes. Cylinder bores are held to .0003 taper, top to bottom and .0005 out of round that's a half of a thousandths. The hair on your head is three thousandths. By the way, proper honing is truly an art, that is why all blocks are honed by Coy personally. It took many years to perfect this procedure. This is also a very time consuming task. We have had reports from race customers of zero leak down after many passes and that is what makes it worth every minute of the time required to do this job right.

Now we will take a look at connecting rods. Most competition engines normally will use new aftermarket race type aluminum or steel rods. We are equipped to rework stock OEM type rods for limited type engines or engines that run in a class that doesn't permit aftermarket rods. These rods are magnafluxed, shot peened, and then are resized on a Sunnen rod honing machine after ARP or SPS rod bolts are installed. The pin ends are normally machined for bronze bushings, and the center to center lengths are corrected at this time on a Becker vertical milling machine. Rods are balanced to within one half gram on both ends.

       The next component that we look at will be the crankshaft and as with the rods, most competition type engines will normally use after market crankshafts. When stock type crankshafts are used they are vat cleaned and oil galleys are rifle brushed. They are then magnafluxed and checked to make sure they are not bent. Cranks are then set up in a Winona CG 280 crankshaft grinder for indexing and regrinding. Tolerances are held tight for proper bearing clearances and the oil holes are chamfered. They are then micro polished and the bolt holes are thread chased. We also offer offset grinding and cross-drilling services.

Now we're ready to balance the rotating and reciprocating assembly. All of the pistons and pins are weighed on a Toledo precision computer scale that will weigh to within one tenth of a gram. We normally get the pistons half a gram from the heaviest to the lightest. Pistons are machined on a vertical mill under the pin boss area, so as to not take away from their strength. Rods are weighed and corrected in the same manner on both ends and again we try to hold them to within half a gram. The rings, bearings, piston pins, and pin locks are also weighed. Now we will make up bobweights to place on the crankshaft to simulate these components and spin the crank on our Winona XL 2000 computer balancer. This machine is capable of balancing to one tenth of a gram, we normally go for one gram. (NASCAR standards are three grams) We also can install Mallory metal in the counter weights to internally balance engines that ,were factory balanced externally, and we highly recommend this for high rpm engines and durability.

The cylinder heads are where we spend more time than any other component involved with the average engine program. Competition engines will normally use new aftermarket type racing heads. When factory type head cores are used they are disassembled and cleaned. Then they are pressure tested to make sure there are no hidden cracks. New heads are also pressure tested. Now for the next operation. The heads are set up in a Winona CMC 30 cylinder head machining center where the valve seats are formed with Serdi type mutable angle & radius cutters, and the seat depths are equalized to two thousandth of an inch and the bowl area is machined to complement the valve seat configuration. The runners and chambers are also rough shaped by machine. At this time we prefer to hand finish the chambers, bowls, and runners. Bronze valve guides or liners are installed before any seat work is done. This hand work takes a lot of time but we feel this is the best way to do the job right.  Yes we know that the buzz word right now is CNC. Coy has looked at a lot of CNC programs and has found very few that are truly ready to run, and they are very expensive.

Used heads are also flat milled on a Winona VM 2000 before any seat work is done because we reference off of the guides for the valve seat centerlines and the deck for valve heights. Spring seats can also be machined if larger springs are to be used. We also machine the guides for Teflon seals, because we want to keep the combustion chamber as clean as possible. Oil won't make good power.

Countless hours are spend on our computerized SuperFlow 600 flow testing to find the valve and seat configuration and chamber, bowl and runner design that will make the engine achieve both maximum flow and velocity for optimum torque and power.

After all machine work is complete the engine is ready for pre-assembly. This consists of checking and correcting piston to deck clearance, setting ring end gaps, checking and correcting bearing clearances, degreeing the cam shaft, checking piston to valve clearance, and any other clearances. After all of these important tasks are done the block and components are cleaned for final assembly.

All engines are assembled by Coy in the CLEAN ROOM, and there is no hurry at this point. After assembly, engines go to the CMRE state of the art dyno cell and put on a new custom built 2000 HP SuperFlow computerized engine dyno for testing and tuning.

This is our general procedure, but there's a lot more involved and it would take a whole book to cover this topic in detail. We have spent many years perfecting our engine building skills and buying the required equipment. Besides, if we told you everything we would have to kill you. Just kidding!