Bullet proof Engine - Part 3

[FRP]

Hi to all and please don't die of shock BC I am getting back to this so quickly! Promised I would !

In this installment we will build the lower end. This will be a little lengthy because it is so easy to make seemingly small mistakes that end up causing big problems or outright failure.

We have all the block prep and machining done and we know our crankshaft is usable. At this point I do a micro polish on the crank, and the block and crank go (one at a time) into a high pressure wash cabinet with a heated solution made by Zep which has anti rust additives so the cylinder bores don't try to flash with rust as you are blowing everything dry. During the wash process I run a series of brushes through the oil galleys and use a special bore brush in the cylinders which helps get all of the micro honing particles out of the bore finish. As soon as the hot rinse water is as blown out of everything the bores are lightly oiled with a micro fiber towel and Marvel Mystery Oil.

Getting the block absolutely anti septic clean is critical to a proper build. This holds true with all of the components which go into an engine. There is no such thing as too clean. I disassemble all new connecting rods and solvent clean them and the bolt threads, new pistons have the grooves and pin bores inspected for any tiny bits of aluminum that could be left from the manufacturing process and are also washed in clean solvent.

Now the block is ready to go on the stand and be taped up for priming and painting. With that done assembly can begin.

First step is installing the main studs which go in only finger tight and should never be bottomed in the thread because bottoming them inhibits them from pulling up freely in the thread bores with no side load. (Remember from the block prep that these main stud holes were prepped with a bottoming tap). If the stock main bolts are retained I still like prepping the threads with a tap as it helps insure even bolt torque.

Now the upper bearing shell can go into the block and it is very important to insure that all of the anti rotation tabs on the back of the bearings engage cleanly with the tang reliefs in the bearing bore. On Audi I5's some of the bearing tabs interfere on main bearing sets with the thrust faces built onto the bearing. This is only on the thrust or number 4 bearing and the interference can be fixed by filing the back of the tang so it fits cleanly into the tang relief in the block.

The lower shells are installed in the main caps, caps are installed and torqued to spec and a final check of main bearing clearance is made with outside micrometers and dial bore gages as outlined in the first installment. With this done we can install the crank. Caps are removed.

Now the upper bearing shells are lubed with assembly lube (I use Redline Assy. Lube) and the crank can be gently lowered into the block. I check for free motion of the crank and install the lower shells in the main caps and lube them. If studs are being used it is easier to put the lube from the stud supplier on the threads before the main caps go on. * A note on thread lube for main bolts /studs, head bolts / studs, and rod bolts - it is imperative to use the type of lube specified by the maker of the bolt or stud. The friction qualities of these lubes vary considerably and it is possible to over or under torque these fasteners with the wrong lube - follow the instructions! Some lubes are too slippery and can lead to over torqueing. The stud washers should be lubed on both sides along with the face of the nut.

Now the main caps are installed and you should make an effort to center them on the crank webs and to pull them down slowly and evenly with a short handle wrench. When they are all snug another check for free rotation is made and the torqueing process can begin.

I always torque in 3 stages, from the center bearing out with a free rotation check as each cap is tightened. It is very important to save 15 foot pounds for the last stage and be sure to pull the torque wrench slowly in a single motion and don't jerk the wrench. If you get hung up then back the fastener off and repeat the last stage.

At this point we stop and use a dial gage to measure crankshaft end play in the thrust bearing. The dial gage goes on the crank nose and we use a medium screwdriver to move the crank for and aft in the bearings. Minimum end play should be .004 and .005 is better. If we do not have this clearance we loosen the main bearing where the thrust is located and then barley snug the fasteners back. At this point use a dead blow plastic hammer and rap the crank nose once toward the rear and go to the rear and rap the flywheel flange on the crank towards the front. This centers the cap which is then re torqued to spec. End play is re measured. If this does not give adequate end play then we address it by honing the thrust bearing to achieve .004 clearance.

Connecting rods must have the big end assembled and bolt threads lubed, placed in a rod vise and torqued to spec. After torqueing the big ends are measured for concentricity and rod to rod consistency of big end diameter. Out of round should not exceed .0002 - if it does the big end can be lightly honed to correct the problem. Rods with more than .001 eccentricity generally must have the parting faces ground and re honed to the correct diameter. This referred to as "re sizing"

At this point rod bearings are installed, rods re torqued and a final check of rod bearing clearance is made. Clearance should be a minimum of .0025 with .003 preferable in high power application. When these minimums are failed to be realized the rods can be loosened by .0005 with extra honing without unduly effecting bearing crush. If more clearance is needed, extra clearance bearings can be sourced for most applications - usually from King Bearing or ACL. * On all of my high horsepower 5 cylinder motors I always install ACL Race Series extra clearance bearings with Calico low friction coating.

The last step with the connecting rods is very important. It is the process of determining and correcting rod side clearance. Side clearance is extremely important and frequently overlooked. It is measured by placing the rod cap with the bearing shell in it on the rod journal and holding it firmly and squarely against the rod journal while measuring the side clearance with a feeler gage placed between the edge of the cap and the flank of the journal. This clearance should be ( and frequently is not) a minimum of .009 with .011 preferable. The side clearance of the rod in its journal is part of the oil bleed rate paradigm of the lower end of the motor. The significant bleed rate is established in the bearing clearance but can be adversely effected if the side clearance is too tight. The bleed rate must be high enough to allow the oil to flow with sufficient volume to efficiently carry away the heat generated within the bearing journal interface. On turbo motors with high bearing loads this is particularly critical - especially as rpm's increase. If the rods need more side clearance they are re assembled (without bearings) and faced on a surfacing wheel on both sides to reduce the journal width until the correct side clearance is obtained.

After these steps the rods are disassembled for a final cleaning in clean solvent.

Next step is assembling pistons to rods. First step is installing one pin clip in each piston. Be very careful with these clips and be very sure they are fully seated in their receiver groove. Pins and pin bores in rods and pistons are lubed with assembly lube and pistons are installed on the rods with the second pin clip installed. I always use a small drift punch through the pin hole and rap the pin back and forth lightly against each clip and visually re examine the clips in their grooves before moving on. * When installing pistons on rods be very careful to follow instructions on pin offset. Many engines have some degree of offset to the wrist pin and it is possible to install them backwards as some pistons don't come marked with arrows or pip marks pointing to the front of the motor - follow instructions.

At this point you want to take a top and second piston ring and place them back side first into the attendant groove of each piston. You need to make sure that the exposed inside edge of the ring falls below the outer edge of the groove land by at least a few thousandths of an inch. This check is done so you are sure the groove is cut to its full depth and that the rings supplied are correct for the pistons.

Now it is time to gap the piston rings. This is a critical process to performance and longevity and should be done methodically and with great precision. Follow the ring / piston manufacturers recommendations for clearance values based on the type of service the engine will be in. Generally the gap clearance ends up being between .005 and .0065 per inch of piston diameter - again use dependent. The more severe the use the greater the clearance. The rings are numbered and placed into the bores and gently rotated into place. A ring squaring device is used to set the ring in the bore for measurement.

The rings are measured with a high quality feeler gage and have their gaps adjusted on a diamond wheel rotary ring filler. I do not recommend trying to file todays high tech ring materials with a file! If you must use a file then make sure it is a high quality fine mill file that is relatively new and sharp, place the file in a vice and file the rings by closing the gap around the file blade and moving the ring so that the filing is done from outside in only. All strokes of the ring around the file should be one direction only - outside in. * It is critical that the ends of the ring remain square during the gapping process. They must be ground or filed so the ends remain square.

Re-measuring must be done frequently to avoid ending up with the gap too large. You can take more off but you cant put it back on. It is very important to de bur the end of the ring where it has been ground. I use metal Revlon finger nail files for this job and it works great. Rings must be installed onto the pistons for the attendant cylinders and the pistons should have their tops numbered to avoid confusion.

Rings may now be installed on the pistons. Follow the ring manufacturers instructions for correct side up and for aligning the rings and their gaps. . Be very sure to place the pip or manufacturer's marks up toward the top of the piston. Some but not all barrel face top rings without a back bevel can go either side up and may not have any mark. Napier Hook second rings must always be installed with the hook towards the bottom of the piston. Be sure to use a proper ring installation tool and never twist the top two rings into their grooves. Oil rings are different and can be spiraled into their grooves. Be sure the oil ring rail gaps are at least 100 degrees away from the expander gap and located on opposite sides of the piston.

The piston and rod assemblies are now ready to be installed in the block. The cylinders should be lightly oiled with Marvel Mystery Oil and them wiped clean with a no lint paper towel. * I do not recommend using anything but tapered sleeve ring compressors. They can be purchased from ARP and piston companies like Wiseco. They are so superior to plier and band style compressors that they are the only choice IMO.

The piston skirts and the oil rings are oiled with a pump oil can with the same Marvel lubricant. Do not pump oil over and into the top two rings and their grooves - leave them dry - they will pick up any needed lube from the oil on the skirt and oil ring. Too much lube in the upper ring pack just impedes ring seating.

Now a final check of ring gap orientation (clocking) is made and the piston and rod assembly is placed carefully into the sleeve and the sleeve is pulled carefully up over the ring pack until the bottom of the sleeve is just below the oil ring. The rod bearing shells are fitted into the rod and its cap, assembly lube is applied to the bearing shells and the piston / rod assy. is lowered into its appropriate cylinder with the rod journal at bottom dead center.

A note here on the piston bore and its top treatment for ring installation. I saved this step for here because it is critical to piston installation; When the block is being bored and honed the machinist must perform a beveling operation on the top of the cylinder at the deck surface. It is done with a cone shaped, hand rotated, beveling tool which leaves a small bevel at the top of the bore which is critical to the rings entering the cylinder without damage.

The piston and rod assembly is now carefully aligned, the sleeve is tapped down square against the deck and the piston is tapped through the sleeve which is being held firm against the deck with your free hand. The piston and its rings should pass the threshold smoothly without hanging up. Tapping the piston through the sleeve must be done firmly but also somewhat gently. If there is any hang up stop immediately - examine the rings, re apply the sleeve to the piston and repeat the procedure. (Never install rings you suspect may be damaged. Call the piston supplier and get a replacement set).

The piston / rod assembly should now push slowly and smoothly to the bottom of the bore and carefully engage the rod journal. Be very sure of piston orientation and make very sure the rod meets its journal slowly and squarely to avoid nicking the crank journal. Rods with bolts in the upper half should have guides covering the bolts before piston install. **If the piston does not slide smoothly down the bore or if anything beyond very light scuff marks appear in the bore finish as the piston is installed then remove the piston and find and correct the cause. With proper block prep and sleeve style compressors these types of problems are very rare. Just don't get lazy or think "it will be ok" . If you think there is a problem there most likely is!

The motor can now be flipped on the stand and the rod cap installed. Always be ultra careful to place the rod cap on with the tangs on the same side. I always number the upper and lower half of each rod cap on the tab side so I can see visually that the caps are correct - post assembly. Most after market rods are pre marked with a production number on both haves. * Make sure and fully lube the bolt threads with the lube specified by the rod / bolt manufacturer and lube the spot faces of the rods where the bolts seat. Install the bolts and tighten them slowly and evenly from side to side with a very short handle ratchet. Once the cap is seated firmly, tighten the bolts to about 20 ft. pounds and shake the rod back and forth in its side clearance. The rod should move slickly and freely side to side and click click freely against the journal flanks. If the rod end is bound up you must disassemble it and find the cause of the problem. Repeat with the remaining cylinders until the block is filled.

With the block filled tighten the rod bolts to spec, one rod at a time and mark the bolts with a marker. With the typical 3/8ths ARP 2000 bolts, torque the bolts in two stages to within 15 pounds of the rod maker's spec and make sure the final torque is applied in a single slow smooth pull.

*** A note on rod bolt torque and torque wrenches. It is much preferable to torque rod bolts with a stretch gage that measures bolt elongation and pre load. Depending on bolt material, the correct stretch is between .005 and .0065 of an inch. The use of a stretch gage also lets you check the free length of the bolts to determine if there are any outliers that may have been over torqued during manufacture which happens far too frequently on less expensive rods. With regard to torque wrenches - use a high quality "click style" 3/8 ths drive wrench. I stay away from half inch drive wrenches because I feel they lack sensitivity in the lower ranges. And by all means don't trust electronic beeping wrenches!

Next installment will be oil pumps, pans and crank balancer installation.

[varia]

Again, excellent

Do you think, it would be possible to add a few pictures for the bigger steps?

[scubagli]

Nice write up!

[Mcstiff]

It is becoming clear that for a "one off" build I'd be sending a block to FRP ;-)

[alxdgr8]

It is becoming clear that for a "one off" build I'd be sending a block to FRP ;-)

+1!
I imagine he does this all off the top of his head too which is amazing to me. Love the detail!

[loxxrider]

It is becoming clear that for a "one off" build I'd be sending a block to FRP ;-)

[FRP]

I'll be sure and add a series of pics before this article is finished.

[Urtorsen]

Hats off to you sir, thank you. I think some people are paying for this kind of advice and know how.


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[Repaair]

Hey Jeff,

What kind of engine machining equipment are you using for the boring, honing, decking, and line honing at your shop?
Do you do balancing in house? If so what machine?

Thanks