Small Block Chevy Rebuild Article

The Block: Back from the machine shop
Ok, so actually this is classified as a re-freshening (if this is a word) but the actual procedure is exactly the same for a rebuild minus some machine work. This is the block after a complete dis-assembly, hot tank and oil journal brushing, honing, and re-washing sitting here waiting for the assembly. Upon dis-assembly we found a worn cam, and cracked heads (the reason for the failure and subsequent rebuild). I miked the cylinders upon disassembly and found only 3 thousands taper on the worst cylinder, thus the cheap rebuild, ie... we will re-use the pistons installing new rings, and use the old crank since nothing was worn, and the journals are still in excellent shape. All other parts (except for the normal reused stuff is new).
Once the honing is done and oil journals cleaned, we cleaned the pistons removing the carbon especially from the ring lands. Once all re-used pieces are clean and covered, assembly will start. Don't scrimp on clean. A dirty engine will fail fast, chewing up the bearings and puting severe scratches in the freshly machined cylinders. A dirty engine is the same as pouring dirt down the carbuetor of a running engine.
To follow is a step by step assembly, and with a good engine assembly manual, and a few specialty tools, there is no reason why you can't do this yourself. I have built engines easilly in a day, but since there is no rush on completion, I am going to string the actual work out to about a week or longer (hey, it takes time to clean my hands and take pictures between steps).
The steps don't show the cleaning or dis-assembly process, and it is just as important as the assembly.
Mark each Main and Rod cap prior to disassembly with a good set a number punches. Number each main cap according to it's relation to the engine, in other words the cap at the front is Number 1 and sequential to the back.
Same goes for the Connecting Rods: On a chevy, the left (or drivers side) of the engine starts with the front cylinder being number one, followed by odd numbers 3, 5, and 7, while the right (or passenger side) of the engine is even numbered 2, 4, 6, and 8. Get a good repair manual and look at engine configuration to see how your particuliar cylinders are numbered.
Get a set of engine brushes, and clean, clean, clean, until no dirt is present anywhere on any parts used in re-assembly. If your not going to reuse something, throw it away, and don't let it dirty up, and clutter up your work area.


The bottom sideThis a view of the bottom with all gasket surfaces cleaned and brass freeze plugs installed. With the cleaning process on going the engine will be wrapped in plastic until we are ready to install the crankshaft which will ultimately be the first step.









crankshaft out of the cleaning tankFresh out of the solvent tank. This crankshaft shows no signs of wear other than a couple of small scratches that we will buff out prior to assembly.
One important note: When storing a crank, always support it standing up, and never lay it down. If layed down, the crank will become bent in a short amount of time with no support on the journals. Same goes for camshafts. If left in the packing box, they are fine laying down, but if you don't have the box, it must hang from a wire or stand perfectly straight and supported from falling. If you accidentally drop the cam, you will most likely buy a new one, as it will shatter when it hits the ground.
Crankshafts may also break or crack if allowed to fall over.


Our new set of headsAs mentioned earlier, a cracked head was one of the main reasons this engine needed repair.
Here is the two freshly rebuilt 68cc 1.94 intake 1.60 exhaust heads we chose to install on this engine. This will be one step to increase compression (over the cracked 74cc heads) thus generating a touch more horsepower. Other torque and horsepower mods will be mentioned later.



uhhhh, the hole where the cam goesOne step the machine shop did that we can't show is the installation of the cam bearings.
Allot of people make the mistake during the rebuild to re-use the cam bearings with a new cam. These bearings are as critical as the crankshaft main and rod bearings.
Worn cam bearings can throw off cam timing, and cause a loose fit of the timing chain which will change timing, and eventually cause the chain to fail, the cam to fail or both.


Main BearingsThe next step is to install the crankshaft.
Here is a view of the 5 sets of main bearings and the plastigauge that is used to check clearance between the journal and bearing surface.











Bearing installationInstallation of the main bearings is a simple procedure but utmost care and attention should be given.
First, make sure the journal under where the bearing will sit is clean and particle free. Any dirt will cause the bearing to warp upon torqueing the caps and may cause the bearing to come in direct load contact with the crankshaft which is very bad.
Second, make sure your installing the bearing with the lock or index tab in the correct position (see arrow), and Third, make sure the block side bearing has the oil hole and the hole lines up with the hole in the block as both halves are not alike.


Here is a view of the block with all bearings installed and double checked to see that the tabs are in the correct position and the bearings flush with the block.
Install the bearings in the caps at this time and also look for and clean any dirt or particles from the caps. Remember: A dirty engine is a ruined engine.
Don't lube the bearings yet!






Installation for clearance checkVery carefully install the crankshaft making sure not to rotate the assembly while dropping the shaft into place. The crank should slide into place easilly and no tapping, pounding, or rotating is needed. If the crank don't go in easilly, a problem may be evident like a bent crankshaft. If in doubt, take the crank to a machine shop and have it checked. If the crank still don't fit, have the block checked for block shift. The block may need line boring, or in worst cases, the block will need replaced.

PlastiguageNow the tedious job of installing the plastiguage. These little thin pieces of plastic can be tough to get in the right location on the journal but with a little patience, they will stick in the middle of the journal and stay there long enough to put the main cap on. Sit the cap on and just finger start the bolts until all plastiguage is on every journal and every cap is in place, then screw the bolts on snug but not tight, infact a general rule is finger tight to start.
Extreme care is needed to make sure the crank doesn't rotate. If it does, pull the cap and re-plastiguage the journals.

TorqueNow the caps need to be torqued.
Again, don't rotate the crank during this step.
In the case of our small block with 4 bolt main caps, the torque specs called for torqueing the inner bolts to 80 lb.ft. and the outer bolts to 70 lb.ft.
Start with half the specified torque. I used 35 as a standard to torque the caps starting from the inside bolts and working to the outside bolts. Once the 35 lb.ft. was set on all caps, I reset the Torque Wrench to 80 and did the inner bolts on all caps, reset to 70 and did the outer bolts.
Again, work from the inside, outward.
Once all bolts are torqued to specs, loosen and remove all the main caps, again makings sure the crank doesn't rotate at all.

Checking the PlastiguageThe small paper container the plasitaguage came in is also the guage for checking the crush on the plastic. I cut each section the length I need with scissors when I install the guage, then use one cut section to measure each journal.
Here the guage shows .002 on this particuliar journal. The specs show a clearance of .001 to .003 as a safe journal to bearing clearance, so we are fine on this journal for assembly. If your plastiguage doesn't fall within .003 or doesn't crush at all, it's time to mike the crank and find out what oversize bearings or possibly a new crank is in order. If you skip the plasiguage step, as some amateur mechanics tend to do due to it being time consuming, you take a big gamble as to whether or not clearance is correct. To tight will cause the bearings to seize and spin and fail, while too loose will cause the engine to knock, have low oil pressure, and the quick failure of the newly installed bearing.

Rear Main Seal InstallationWith all the journals checked, remove the crank and install the rear main seals found in the gasket set.
Very Important: Make sure the lip of the seal points inward and NOT toward the back of the engine.
If you get this backward, an almost instant rear main seal leak will happen when you start the engine the first time.
The last thing you want to do is remove the pan from underneath the vehicle, pull the oil pump, rear main cap, and replace the seal, this time in the right direction.

Assembly lube on the bearingUsing a good engine assembly lube, put a good puddle in each journal, and cap and sit the crank in place for final installation. Some engine mechanics opinions differ on whether to remove the plastiguage once the clearance is checked. My belief is the plastic is non-abrasive so I don't worry about removing it. The first time the crankshaft rotates after assembly, most traces of the plastiguage are gone.



Also important is to dip each bolt in oil upon final assembly. This aids in proper even torque load on the bolts which will prevent the bolts from possibly coming loose or breaking due to binding during the final assembly process.









Final assemblyAssemble and torque each cap same as done when plastiguageing.
Each cap has to go back, in the same place as it was when dis-assembled for rebuilding. Get a set of number punches and mark each journal on the same side of each cap. Also note that most blocks including chevrolets have arrows that must be pointed toward the front of the block.
Once all caps are in place, torque and recheck (Yes I go over my assemblies twice and sometimes three times) to insure you didn't miss a bolt, rotate the crankshaft to make sure it moves freely.
No severe drag should be encountered. Check for any binding, or dragging during any part of the rotation.


Mrs. Clean-------Mrs. CleanThe next step on our assembly is to clean pistons and rods (since we are reusing ours) and remove any carbon and build-up from the ring lands. For those that went to the machine shop and had the old pistons pressed off, and new pistons pressed on, nows the time to inspect the pistons for crackes around the piston pin, and make sure rods are installed in the right direction (yes even machine shops make mistakes).
Since we will re-use the pistons for this project, we soaked the pistons in the solvent tank for a couple of days, removed any excess carbon, inspected each piston for burning or defects and got ready for re-assembly.
The picture above shows Ida doing the dirty work.


While Ida finished cleaning, I opened the box that contained the Piston rings.  Depending on manufacturer, rings can come in a box (as the picture shows) or in individual packets, or envelopes but all should be marked bottom, middle, and top. Pay close attention during disassembly to see where each ring sit in their respective grooves. 



Installing the ringsWith the first piston cleaned, the job of installing the rings begin. Start with the bottom oil rings and install the grabber (or little serrated looking non-spring ring) and then install the two wiper rings to lock the grabber ring in position.
Rings can be broke if put under the slightest load bind so extreme care is needed.  The procedure is hard to explain, but you want to carefully slip one end of the ring over the edge of the piston while keeping the other end sitting on top of the piston then carefully screw the ring around the circumference until the ring is in it's groove. You should practice with an old ring to perfect this installation process before you try it with a new one. If you can't understand what I am getting at, go down to your local autoparts store and purchase a ring installer. The installer grips the ends of the ring and spreads them for direct install. While this works fine, I prefer the twist or screw method since it's doesn't stretch the ring out of shape.
Once the oil grabber and two lock rings are installed, the middle compression and top compression rings is next.  Most ring manufacturers place a dot on one side of the ring.  This signifies the top or this side up of the rings.  Always look for this dot, and make sure it's facing up.
Also make sure not to get the second or middle ring and the top ring mixed up when installing.  Most middle rings are alloyed different and will burn up if placed on the top groove directly against the heat of combustion.
BE ALERT!!!

Setting the Ring CompressorHere's another purchase item you must have or borrow to do the job since there is absolutely no other way of doing this.  This Ring Compressor is a compress type spring steel collar that compresses the rings by clamping down around the piston with the use of a locking clamp built in to the compressor. While many styles are available (including some cheaper versions with regular hose clamps) this style is the one (and in fact the same compressor) I have used for the last 20 years and have never once broke or chipped a ring.  Make sure the compressor is tight all the way around with no gaps between the piston and compressor.  A slight tap with a hammer around the compressor will insure the rings are seated in their grooves and ready to install.

Here is the assembly with ring compressor, rod bearing and bolt protectors installed and ready to be slid into it's respective cylinder. Make sure the rod bearing is installed correctly since it's hard to change or install once the piston is in the bore. The protectors on the bolts keep the rod studs from scratching the crankshaft throw during assembly and should be included in the kit.  If the protectors are not in the kit, get two 3 inch lengths of 3/8 fuel line and put over the studs.


Lube the cylinder with assembly lube.  Be generous here since this is the lubrication the cylinders will use until motor oil gets sloshed up there during start up.











Here is a view of the installation of the piston into the cylinder.
Notice I am using the rubber handle end of a ball peen hammer to tap the piston through the compressor and into the bore.  Also note the direction of the piston as the index mark or notch in the top of the piston needs to be facing toward the front of the engine.  Make sure the compressor is tight against the cylinder so the transistion between the compressor and bore is smooth.
The last thing you want to happen here is for the ring to slip out at the bottom of the compressor and snap off as you give the piston a firm tap to send it into the bore.
Also notice we are building this engine outside.  We could have moved into the shop in a nice sterile environment for this, but since we wanted to suit the build for everyone, we chose to do this out under mother nature.  If extreme care to cleanliness is observed and with a good concrete floor under your feet, you can build an engine anywhere as long as high winds and dust aren't around while you have the engine uncovered.  Afterall, the outdoors is allot cleaner than allot of shops I have worked in, all kidding aside.

Use extreme care once the piston is in the cylinder, and keep tapping the piston until the rod journal seats with the crank throw.
Make sure the piston is not twisted and goes in straight as a crooked or turned rod can nick the crank journal and cause you to do some deburring of the crank which is not a fun job.







Once the rod is seated insert the other half of the bearing shell in the rod cap, plastiguage each bearing as you install each piston and torque the cap (on this engine we torqued the caps to 45 lb.ft.).  Check the plastiguage and if within limits, coat liberally with assembly oil and install and retorque the caps.
Repeat this for each cylinder as you do each cylinder so as to not forget a step or accidentally forget to torque a cap.  Again, I double and triple check my work to make sure I didn't forget something.

Since the person that origionally dis-assembled the motor used a punch on the cap to mark each cylinder, we took the time to correctly number stamp each rod so that the next person (in the far future) that dis-assembles this engine already has cylinder orientation to the pistons.
Stamping each rod before dis-assembly takes allot of headache out of trying to figure out where each piston and rod goes for re-assembly.  Remember, utmost care is critical in the successful rebuild of an engine.

Finally as we end this session, make sure (no matter how clean your environment) to bag the engine in a couple of large garbage bags.
Seal the open ends with coated wire or wire ties or anything that will seal.
This will ensure your engine will be as clean as you left it the next time your ready for more assembly work.






With all the plastiguaging behind us things speed up now as we strive to finish this project with about 4 more hours of labor on top of the 3 hours we already have invested.
Here the Victor Head Gasket is fitted and readied for the head.








A little touch-up with the die-grinder was in order. We used a gasket cleaning pad that is non-abrasive and it's only enemy is gasket material. Don't use sand paper as it could create a fisher or scratch large enough to cause a leak.










With the head in place, dip the head bolts in clean oil and install each one for a total of 17 (that is on a small block chevy).  There are 3 lengths of bolts but it will be easy to figure out which ones go where.  Tighten the bolts just finger tight for now.










This is a good time to clean out a small pan or in this case cut the bottom out of an old antifreeze jug and clean it out and I mean clean.  Put your lifters in this container and completely cover with oil (in an antifreeze jug it takes just under a quart) since this step will be next after the heads, and this moment of preparation gives plenty of time for each lifter to soak up oil for assembly.  Pictured is the Cam, Lifters already soaking, and the Cam Lube which prevents the cam from abnormal wear on startup.

On this engine the correct torque for each bolt is 65 lb.ft. in sequence which will be shown in any good shop manual.  Remember to use half torque for the first sequence and then retorque to the correct value.  Allot of engine builders will come back once the engine has been run for an hour or so and retorque the heads but that is not necessary in my opinion, but I will give the initial torque of 65 about 15 minutes to set in, then come back and retorque the bolts again in sequence to 65 again.  I find I get another nudge out of each bolt by doing this and although it slightly increases the bolt stress it will not cause any problems since the bolt torque specs on these grade 8 bolts is allot higher than the stress we are putting on them.  Repeat this step for the other head.

CamshaftAs we install the Camshaft a generous supply of Cam Lube is poured onto each lobe and main surface as we slide it in, being extra careful not to slam the lobes against the bearing surface and using gentle pressure to guide the cam in, and if at any time the cam has to be forced, into the bore, something is wrong and the cam should be removed and surfaces checked.  Don't worry about this stuff dripping off since it's as thick as grease and sticks to everything including your hands and is tough to wipe off.

Installing the liftersWith the cam in place, pump each lifter with a pushrod a couple of times while still in the oil to dislodge any air bubbles that may be present and then put a lifter in each lifter hole and make sure each one will seat easily without having to force them.









Timing Chain InstallationNext we install the Timing chain and gear set.  We chose the Cloyes double roller set with advance/retard crank gear which allows you to advance or retard the cam 4 degrees.  Advancing the cam increases torque and cuts horsepower while retarding the cam increases horsepower and cuts torque.
We chose a 0 degree or straight up setting since we had chose a RV2 high torque cam and no advance or retard was recommended.  Install the crank gear first, align the marks straight up and then install the cam sprocket and chain, making sure the marks line up.  Install the 3 bolts in the cam and tighten to specs.
Note: Incase your not famaliar with oil galleys, check to make sure they are all plugged before this step as you don't want a cam sprocket in the way of driving the half inch plugs into the lifter galleys, infact this might be a good time to check to see that all the galley plugs are installed, which you should find in that good shop manual you purchased to show you the things I can't on this webpage.

Clean the timing cover, find the gasket in your kit, add a light coat of gasket sealant and install the timing cover.  This is the first piece of sheet metal which indicates we are getting closer to completion.











Here is a view with the timing cover in place. Be sure to double check the timing chain and gears for proper alignment and the cam bolts are tight to specifications.














With the timing cover in place it's now time to install the Harmonic Balancer.  Do not soak this part in solvent or immerse it in anything other than soap and water to clean off the grime.
Solvents and oils will soften the rubber that insulates the balancer and allows it to do it's job and the balancer will slip or worse, fall completely off causing allot of damage.
The balancer is shown here being pressed on and set to 0 degrees putting number 1 cylinder at Top Dead Center (TDC).

Valve adjustments can be one of the toughest things to get right on any engine and careful attention to the shop manual should exercised.
On our small block, the specs show a 0 lash against the hydralic lifters, so with each lifter at 0 lift we tighten each rocker till tension is felt in the pushrod and then give the rocker nuts and additional 1/2 turn, which gives some preload to the lifter but doesn't bottom it out in the lifter bore.


Here is a view of the back of the motor showing the shiny cam plug.
Also note the two block holes that don't have freeze plugs installed yet.  If you wait until the engine comes off the engine stand like I do to install the last two plugs, just don't forget to do it, infact I have seen some mechanics that tape the plugs to the flywheel just to remind them that it needs to be done.




Before we make the engine too top heavy on the stand, it's time to roll the block over and install the oil pump.  With a new pump out of the bag, we installed the oil pick-up, aligned the screen parallel to the pan bottom, then tack welded the pick-up to the pump to guarantee that the pickup don't end up twisting up out of the oil due to vibration, or just Murphy's Law inflicting a suprise on our assembly.



With the oil pump installed and the bolt torqued to spec, it's now time to clean up and install some more sheetmetal.













With the pan cleaned and gaskets installed the pan was on and bolted in place in no time.
Care should be taken when cleaning the inside of the pan to clean all the grime out of the windage tray which is the area under the flat peice of sheetmetal that covers part of the bottom of the pan.







With the engine upright the mating surface for the intake manifold was checked and wiped of oil as needed and the intake gaskets placed and ready for the Intake Manifold.











The intake manifold is carefully set in position as to not to disturb the gaskets and 12 bolts installed and torqued to 30 lb.ft.
Make sure the end gaskets don't slip out during the installation and gasket sealer should only be used around the water jackets and at the corners where the front and rear seal mate with the intake gaskets.






Final assembly is finished with the installation of the Valve Covers.
Plenty is left to do with a coat of fresh Chevy Orange Paint, the installation of the Carburetor, Exhaust Manifolds, Water Pump, Fuel Pump, as well as Distributor, and all the other final prep for installation into the truck.
While this series is just the basics, it should point the basic "shadetree mechanic" in the right direction to building the engine and saving a few bucks on labor.
Nothing is more pleasing than to hear the fruits of your labor start up and purr like a kitten, and give you many miles of trouble free service.
Just remember to follow the manual, get the right tools for the job, and if you get stuck, seek help from a reputable mechanic.  Remember, he started out doing what your wanting to do, and should have no problem with giving you advise on your project.
Good luck on your mechanical endeavors.

And finally we masked off all gasket surfaces still waiting for something to be bolted to them and gave it a fresh coat of Chevrolet Orange Paint.  We then added the Fuel Pump, Chrome Valve Covers, and Exhaust Manifolds as well as the Harmonic Balancer Pulley.
Before we stick it in the truck we will add the Water Pump, Carburetor, and have the Distributor all rebuilt and ready once the engine is bolted in, then comes the task of finding where all the brakets go, misc. wires and hoses.
About another 2 to 3 hours of work and the truck will be running.
One more overlooked item to do prior to installing in the vehicle, is to prime the oil pump and run oil through the oiling system.  Hook an oil pressure guage to the pressure tap at the back of the engine and monitor oil pressure while priming, and make sure it's good and steady.
Check around for a primer, since most mechanics have a busted or converted distributer for hooking to a drill and doing this job, which makes the whole task allot easier, but nonetheless do prime it, and give your engine the extra lubrication it needs on start-up to prevent premature wear.
 

 

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