Technical information, instructions and procedures for engine re-assembly on a 1960's era Chevy 235 cubic inch 6 cylinder.

Part Four of a Six Part Series.

Engine Re-assembly Section 1 of 2.

Tech Series Logo Version 3 for Moonlight Engineering Moonlight Engineering Professor Tech Speaks Logo for Technical Articles.

Rebuilding a Chevy "Stovebolt" Six  Engine Part 4

Engine Re-assembly Section One

SkaRoody the disenfranchised sheet metal screw. SkaRoody the sheet metal screw with a split personality. SkaRoody the drug addict sheet metal screw. SkaRoody the meth head sheet metal screw. SkaRoody the drunken sheet metal screw. SkaRoody the nympho; designed for quick screws.

Part Three demonstrated how internal measurements can help you determine what work needs to be done on your Stovebolt engine. Part Three explained ways to check for cracks in the heads and block plus it suggested methods as to how one goes about identifying a good machine shop. This last step is especially important because the dialogue you establish with your machine shop, and the quality of work the shop delivers, will go a long way toward ensuring a smooth running and long-lasting Stovebolt engine performance.

Dual PisstonFangers give your Stovebolt Teeth!

You will want to discuss with your machine shop such things as to whether or not to install hard valve seats in your Stovebolt engine's head, whether or not to install special, no-lead valves, and whether or not to install bronze valve guides. Chances are, unless you only drive short distances under light loads you will want your old valve seats machined out and modern valve seat inserts pressed-in. These hardened valve seats are designed for use with no-lead fuels unlike the OEM seats which deteriorate without the use of leaded fuel. Alternatively, you may want to install no-lead valves. You don't need to replace both the new valve seat inserts and no-lead valves, because either one of these will provide the protection needed for daily driving using unleaded fuels.

Build it right and bring a Car Toon to life.

Generally speaking, the installation of new valves is the less expensive way to go. Furthermore, some engines have rather delicate valve seats that cannot be machined to install inserts. Your best approach is to consult your machine shop as to which is preferable for your application. While your at it, don't forget to inquire about BRONZE versus IRON valve guides for your application. The softer bronze guides may be preferable for Flathead engines; where the Flathead oil system has trouble getting enough oil to that portion of the engine. Overhead valve engines, which do not have the oil flow problem of the Flathead, harder iron valve guides usually are preferred because they have a longer life, before showing signs of wear, when compared to the bronze valve guide.

DooFuss Dingus is really fussy on how engines are put together, and that's a good thing.

Regardless of whether you have checked the head, deck, and bearing saddles for cracks, your machinist should also conduct a Magnaflux test, just to make sure nothing was missed. During a Magnaflux test, the engine part is subjected to a strong magnetic field and small, metallic particles are sprinkled on the component's surface. The small particles tend to collect on any cracks in the surface.

The Co$t of this test is, by far, preferable when the procedure discovers a hidden crack in the block BEFORE ( rather than AFTER ) opening up your wallet to purchase costly machine work, parts, assembly and installation labor. Spend the cash for a professional Magnaflux test, make sure the machine shop you use heats the block and head prior to conducting the diagnostic, as some defects do not appear when cold; it would be a real shame to find out your Stovebolt runs just fine until it reaches operating temperature. Chevy straight six heads are notoriously prone to cracking, so if you are doing one of these engines, have the head checked carefully and find another one if your original has problems. Additionally, have the machine shop balance your engine. Pistons vary in weight and should be matched up by drilling out small portions of metal until they are all equal. The crankshaft should be balanced with the flywheel and clutch attached, so the assembly will spin smoothly as a unit, with no vibration. The machine shop should straighten the cam, crankshaft and connecting rods as needed.

Early GMC in a patina way.


Remember these speed shops? Local speed shops used to be the Saturday morning meeting place for the hot rod cult.

Once your machinist has informed you as to (1) which undersized bearings, (2) what size and type (cast or forged) pistons required and (3) you've determined what type of valves (or inserts) you want installed, then call or go online to a antique auto or truck parts supplier and order your items. Always buy a quality engine gasket set, e.g., FEL-PRO brand, too. Additionally, It is strongly advised to order a new or re-manufactured water pump, oil pump and fuel pump as well. Using the ELl-PRO link above, I found a high volume oil pump under the Sealed Power brand for a 1961 Chevrolet Apache 10 pickup with a 235 c.i.d. L6 engine, part number 224-4157. I'm willing to bet you, the reader, was not aware that a high volume oil pump was available for this vehicle. This just goes to show how advantageous part research can be! BTW: Stay away from rebuilt parts as their wear, i.e., failure, rate is significantly higher than new or re-man parts. Installing an aluminum or steel camshaft timing gear, rather than, the original type gear with fiber teeth. The aluminum or steel gear will be a bit noisier, but it will last indefinitely, unlike the fiber one, which is good only up to 80K miles.

Give your engine the Tagster paint scheme.

Always separately paint all the engine parts prior to the re-assembly process, time consuming as this task is, the end result of the overall look of the engine is, in a word, bitch'in.


If you want the checkered flag...

Before re-assembly, clean the engine carefully to remove machining debris. This also provides an opportunity to closely examine the engine and make sure the machining work was done correctly. Wash the outside of your engine with lacquer thinner, then, using a rifle bore cleaning kit, scrub all the little oil passages in the block: Dip the bore cleaning swabs in light oil then work them up and down the passages. Keep cleaning until all of the metal shavings and dirt from the machine work are removed. When your cotton swabs emerge white after inserting them all the way into the passages, the galleries are clean.

Moe Dee-Kannic loves to clean and restore old iron and it shows.

Now thoroughly clean the cylinder bores and bearing journals with rags and light oil. The grit left from the machining operations can cause your engine to wear rapidly. Any foreign substances will be carried throughout the engine by the oil, so shavings in the block can find their way to the bearings and ruin them too. When everything is impeccably clean, paint your engine's block, head, pan and other components, so when you assemble them the edges of the gaskets will not have any traces of paint. Judges and knowledgeable friends are likely to knock you down a few points if your car has painted gaskets. Cover flecks and mating surfaces with cardboard or stiff paper cut roughly to size. Since this type of painting generally is done with aerosol cans, you don't have to worry about taping the cardboard in place. Before painting the sides of the head, set the valve cover, which is the same color as the engine anyway, in place to protect the rocker arm assemblies from overspray, and install an old set of spark plugs to keep paint off of the plug hole threads. Paint the side plate, bell housing and clutch inspection pan too. Let your parts dry a day or two before proceeding. Naturally, you'll want to have the correct paint for your model, year, and engine type. An automotive paint supplier can help you in that regard.


Sweet Hot Gas inspection procedure requires one to look over everything very slowly.

Start checking the machine work by inserting the pistons, one by one, into their holes alongside a long, 1/2 inch-wide feeler gauge attached to a fish weighing scale. On the Chevy six engine, you need a gauge .0015 inch thick. For other engines, check your shop manual for the specified clearance between the piston and cylinder wall. Insert the feeler gauge at 90 degrees to the wrist pin. Now insert the piston and gauge until the piston pin is half way into the cylinder.

Pull out the gauge using the fish weighing scale. If the scale reads between 7 and 18 pounds, your pistons are within tolerance. If your scale reads lower than 7 pounds, your pistons are too loose. If your gauge reads higher than 18 pounds your pistons are too tight. If they are too tight, you can probably have the machinist hone the cylinders a little so they will fit. If they are too loose you may need to have them knurled to size or go to the next larger size piston and have the engine bored again.

Ga-Reese Monkey your slippery goo-ah source.

Don't be tempted to put your engine together if the tolerances aren't right. If the pistons are too tight, they may seize when the engine reaches operating temperatures, or at the least the engine will be very hard to start when warm and the pistons will wear quickly. On the other hand, if your pistons are too loose, you will have annoying piston slap and your engine will burn oil.

Check your piston rings in their lands on the pistons using a feeler gauge to insure that they have the correct clearance. On the Chevy, the fit around the compression rings should be between .0020-inch and .0035-inch. The oil ring is okay if it has no less than a .010-inch clearance. Also check your compression ring opening gaps by slipping the rings into a cylinder bore one by one and squaring them with a piston inserted upside down into the bore. The gaps should be .007-inch to .0020-inch when measured with a feeler gauge.

Moe Dee-Kannic loves to work on old iron and it shows.

Rat Fink Tool delivery to the rescue.


Rat Fink Tool delivery to the rescue: tighten and torque.

Before you begin assembly of your engine, pick up a FACTORY SERVICE MANUAL for your car or truck and study the procedures. Each engine is different, so no set of general instructions, like Chilton, will completely provide all the information you will need. The engineers who designed the components, explain how those components are supposed to function, how to remove and replace the component and how to overhaul and maintain the component.

Mr. Cinch-it-right the torque monster.

You get the complete Lowdown, in a FACTORY SERVICE MANUAL, from the guys who thought-up the individual mechanical component marvels working in unison to function as a vehicle. Sure, the FACTORY SERVICE MANUAL is expensive and it is worth every cent it costs.

Also work methodically and carefully and keep in mind that when it comes to building engines the old adage, Measure Twice Cut Once, very much applies.

1956 Chevrolet pickup, panel and flatbed line art renderings.

With that in mind, start the assembly by smearing the cam bushings (these usually are pressed in at the machine shop) with a thin coat of assembly lube, then carefully slide the cam into place. Be careful not to bump and damage the bushing's. Roll the wick seal into the rear main bearing using a round dowel and working from the ends to the center. Using a sharp single-edged razor blade slice off the excess seal exactly level with the mating surfaces. You can use a piece of wooden dowel the diameter of the rear main bearing to help press the seal into place and to hold it while you are working on other things.

Mr. Skelly's Bone Box.

Clean the end cap bearing journals as well as those in the block with lacquer thinner. This is important because one bit of grit will cause a deformity or bump in the bearing shell which will cause heat, friction, and early bearing failure due to insufficient clearance. In addition oil or grease on a bearing saddle will make it more likely for the bearing to spin in its journal and may upset tolerances as well. Slip the main bearing shells into place in the main bearing saddles and end caps.

On Chevy six-bangers, be sure to install the upper bearing halves so the smaller of the two oil holes will be toward the camshaft when the bearing halves are rolled into place. If you are working on another kind of engine, check your FACTORY SERVICE MANUAL for the correct procedure for your vehicle.

The OG's are watching you dumb farm boys trying to wrench out a Cali quality six shooter engine, so you better not fuck it up Kansas; cause if you do, these BMF OG's will find you, strip you naked and completely grafitti your flabby-chubbies with permanent markers and drop your wimpering ass at the local Walmart so your friends can laugh at you too.

Once they are in place, smear the bearing surfaces with a thin coat of assembly lube, or motor oil, then get a friend to help you set the crankshaft gently back into place, making sure that its gear teeth mesh with the timing gear on the cam and that the little timing marks on the gears line up properly. Next, smear a little assembly lube on the bearing surfaces of the main bearing caps, and tighten the special, self-locking pal nuts. Never use ordinary nuts on main bearings, as they would come loose in service and wreak havoc with your engine. On our Chevy six, three fresh .002-inch shims need to be placed under either side of the intermediate main bearing end caps. Then the main bearing caps are evenly torqued in place. This is accomplished in three stages working in rotation until the torque equals 100-110 foot pounds. (This spec is for the Chevy six - your engine may vary.)

Turn the crankshaft using your hands. You should just be able to rotate it with some effort. If it turns easily, it is too loose. If it won't turn at all, it is too tight. If you have either problem, check your bearing clearances with Plastigage. Be sure to wipe the bearings clean, then follow the instructions on the package. Bearings that are too loose will not hold oil pressure. Bearings that are too tight will not get enough oil. Either situation will ruin the bearings.

Before installing the pistons and rods, check the end play in the crankshaft by forcing the crankshaft all the way forward or aft, then slipping a feeler gauge between the bearing end cap and the base of the crankshaft counterweight. The reading should be between .003-inch and .009-inch. If it is not within tolerances, replace the rear intermediate main shells and check again. Also, on the Chevy, check the lash between the timing gears with a feeler gauge. It should read between .004-inch and .006-inch. Install the rings using a ring expander, and be sure to arrange them so their gaps are in the correct positions according to your shop manual. The three-piece, oil-saver oil rings are a good idea on most engines.

Wrap the big ends of your rod bearings with rags and tape so they will not score your cylinder bores or damage your crank journals while you are installing the pistons. Coat the cylinder bores with motor oil. Using a ring compressor, slip the pistons into their bores, making sure they are facing the correct direction. (On a Chevy six the piston pin clamp must face the camshaft side of the engine.) Gently push or tap the pistons down into their bores but be careful not to damage your crankshaft by bumping it with the big ends of the connecting rods.

Again clean the bearing saddles on your connecting rods with lacquer thinner making sure to remove all grit and dirt. Slip the insert bearing shells into place then coat them with assembly lube. Install the bearing caps making sure the numbered side is toward the camshaft on the Chevy or follow your punch reference marks if your engine has no reference marks. Now torque the end caps using only self-locking nuts to 35-45 pound-feet of torque. Tighten them evenly in three stages.

Look over the job carefully and make sure you haven't forgotten anything and be sure to wrap your engine in heavy plastic when you quit working for the day so no dirt or grit can invade.

Next up: installation of the valve train and cylinder head.

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I'm so poor I can't afford to buy crayons to draw this machine much less build it in real life.



Hey I was poor too, once, and that was a long time ago, but I have massive balls of steel and robbed a bank, got away with it, the statute of limitations has passed (just kidding, I'm still poor).

Don't you wish you were not such a poor frump so you could afford to build one of these? John Harlowe's Moonlight Engineering at AUTOBLUEPRINT.COM - Home of the Original Garagesters.

AUTOBLUEPRINT.COM - Home of the Original Garagesters.

Don't you wish you would have...

Old Plug Eye has a high octane addiction, give him anything less and he will fucking murder your sad cast piston ass.

Old Plug Eye has a high octane addiction, give him anything less and he will fucking murder your sad sagging ass.