Installing Copper Head Gaskets
Copper head gaskets were used on early Chevrolet car & truck engines dating back to 1916. Early engines require special steps for proper installation of these gaskets. The cylinder head most likely has been removed for some kind of major repair. This can include blown head gasket, valve job, crack repairs on the cylinder head or block, cleaning of the water jacket from major corrosion buildup. Whatever the cause for the repair, proper installation of the new head gasket will make the job complete and trouble-free. We will assume that whatever repairs were needed have been completed.
Whether you are using a reproduction or an original copper head gasket, following these steps will help give longevity to a difficult job. The first step is to keep things clean. If the block surface or head surface has excess gasket material, sealer or other foreign material, it is vital to make sure these surfaces are clean. Before scraping the block surface, put clean cloths into each open cylinder to prevent foreign matter from getting into the cylinders. Use a gasket scraper to clean the surfaces of the head and block.
Now is also a great time to clean the threads in the block for the cylinder head bolts. CAUTION! Be sure to use the proper tap for the head bolts on the engine. Early 4-cylinder Chevrolet engines (1916-1928) have an unusual thread: 1/2-12. This is a British thread and no longer commonly used in the USA. Use of the wrong tap can severely damage the threads so be sure to get it right. All other engines with 1/2â bolts use a US Standard 1/2-13 thread. After chasing the threads with the proper tap, clean out each hole with a blast of compressed air or shop vacuum to remove all foreign particles. When all of the cleaning is done, remove the cloths in the cylinders. Use compressed air or a vacuum to clean up any residue. Early Chevrolet engines are prone to rust flaking in the water jackets. Insert a magnetic retriever into the block & cylinder head water passages. If a large amount of rust is in these areas, it must be removed. With the cylinder head off the engine there is a great opportunity to clean these areas. Do not fail to take advantage of this opportunity while the head is off the engine.
If there is substantial rust buildup in the engine water passages, consideration should be given to removing the engine for proper cleaning. The best way is by removing it from the vehicle, placing it upside down on an engine stand. (Donât forget to drain the oil first). A high pressure water nozzle will force out the corrosion from the water jacket areas. Large flakes of rust may have to be removed with needle nose pliers if the flakes are too big to fit through the holes. Getting these passages clear of foreign material is vital for good cooling and proper engine operation. Replacing old soft plugs (freeze plugs) in the engine should also be done at this time. Though cleaning water passages is a huge job, it is well worth the time to prevent overheating and hot spots in the cylinder head.
If the cylinder head and block have not been surfaced, they should be checked for warping. Use a straight edge and a .010 feeler gauge. Run the straight edge crossways from side to side on the engine block and head. Check to see that the feeler gauge will not slip under the straight edge at any point. If there is more than .010â clearance, the block or head should be surfaced. If the block is not straight, a good flat file can be used if it is not too bad. Be sure to use cloths in the cylinders to prevent foreign matter from entering the cylinders. If re-using original head bolts, they must be cleaned. A bench grinder with a wire brush is a great method to insure a good job of cleaning. Inspect the bolts for irregularities including stretched threads, bent bolts or severe rust pitting. Replace marginal bolts with new or good used bolts.
Installing the cylinder head is made much easier and safer with use of alignment dowels. These are easy to make out of old head bolts. Clean the threads of two used cylinder head bolts. Cut off the heads of the bolts right under the head using a hack saw or band saw. Use a grinding wheel to put a beveled edge at the top of the bolt, where it has been cut off. Tighten each bolt in a vise and use a metal hack saw to cut a 1/4â deep screwdriver slot into the top of the bolt. These dowels can be installed in a staggered pattern in the middle of the engine, one on either side of the engine. Oil the threads of the dowels and install them finger tight so they will be easy to remove once the head is in place. Carefully remove the rags in the cylinders and blow off the engine with compressed air to remove any foreign matter that remains. If you prefer to use a gasket dressing, now is the time to put it on the block and copper head gasket. Gasket dressings are useful to take up irregularities in the block or gasket surfaces. Anti-seize or copper gasket sealer are two that we have used successfully in the past.
Compare the new head gasket to the original to make sure all holes and contours are the same. Place the copper head gasket over the two alignment dowels and check to see that the gasket is perfectly aligned. You are now ready to install the cylinder head. If the engine is still in the vehicle, it will be helpful to have a second person to help set the head in place on the block. Lift the head over the dowel pins and line them up. CAUTION! As soon as they are aligned, the head will drop into place unless it is supported. Lower the head slowly so there is no damage to the gasket, engine or the head.
Have the clean head bolts in a pile nearby along with a small container of new engine oil. Lower each bolt into the oil so that the threads are covered in oil. Install each bolt and turn by hand until a few threads catch. There should be no binding as the first threads are inserted. Check for bent bolts, dirty threads or misaligned head if the bolts bind. Once several head bolts are started remove the two dowel pins with a screwdriver and insert a head bolt to replace each of them. There is a specific pattern in which to tighten the cylinder head bolts. Refer to your shop manual for this pattern as it varies depending on the year and size of the engine. Since there were no torque specifications for early engines, there is a universal torque specification that we offer as a guide if your engine has 1/2â bolts â Torque 1/2â bolts to 67 foot pounds. Start by torqueing to 30 foot pounds, then 50 foot pounds, and finally, to 67 foot pounds. After completing the torque pattern at 67 pounds, go back and check each bolt one more time at 67 pounds. CAUTION! Early Chevrolet 4-cylinder motors have a weak spot in the front and rear head bolt area. Tighten these bolts with caution and even to slightly less foot pounds.
After the engine has been warmed to normal operating temperature, it will be necessary to re-torque the head bolts. Run the engine for 5-10 minutes or take it on a short drive. Once normal operating temperature has been reached, re-torque the head. After the head has been torqued for the second time, a valve adjustment should be performed. In addition, check the distributor point gap and timing of the engine. These procedures will give you many miles of trouble-free driving.