How to rebuild an engine
(→Testing and break-in: trhetryjteyjetyjtyj) |
(→Testing and break-in: Minor clean up) |
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Oil formulations are being changed due to pressure from the OEM's and EPA. Zinc and phosphorus tend to coat O2 sensors and plug catalytic converters resulting in warranty claims as well as contributing to dirty exhaust emissions, so they are being eliminated from motor oils as we speak. These elements were used in the oil to provide extreme pressure lubrication and protection from galling on heavily loaded engine components such as the cam lobe/lifter crown interface. The oil companies have no choice, they have to follow the guidelines imposed on them. | Oil formulations are being changed due to pressure from the OEM's and EPA. Zinc and phosphorus tend to coat O2 sensors and plug catalytic converters resulting in warranty claims as well as contributing to dirty exhaust emissions, so they are being eliminated from motor oils as we speak. These elements were used in the oil to provide extreme pressure lubrication and protection from galling on heavily loaded engine components such as the cam lobe/lifter crown interface. The oil companies have no choice, they have to follow the guidelines imposed on them. | ||
| − | The loss of those high pressure lubricant suppliments from the motor oil now available | + | The loss of those high pressure lubricant suppliments from the motor oil now available had less impact on newer engines because of the change to roller cams. With them, there is no special procedure for break-in. You just oil the lifters, drop them in and no other special break-in procedures are needed for the cam and lifters. Obviously the rings and other new components will still require a break in period, but with a roller cam the biggest problem associated with breaking in a rebuilt engine (flat tappet cam lobe/lifter failure) is a thing of the past. Be advised though, that there could be a problem with mechanical roller camshafts in a street motor. In many cases the best valve train for a street motor would begin with a hydraulic roller cam. Most hydraulic roller cams will have a rev limit of around 6,000 to 6,200 RPM due to the weight of the components, the design of the hydraulic lifter and the cam lobe design. If a higher powerband is wanted or needed, you've moved out of the street engine realm and are now into race engine territory, and should be looking into a solid roller valve train. The old flat tappet technology is just about dead, save for a few die-hards. |
| − | This is similar to how the current ignition systems came to be. Kettering invented the points-type ignition system early in the last century and it endured for some 70 years. When it came time to clean up the environment, the OEM's switched to electronic ignition and we never looked back. Points-type ignitions have been replaced by HEI-type ignition systems. Now we have moved to solid state ignition with a coil for each cylinder, controlled by computers and rare earth spark plug electrodes to provide good performance and acceptable emissions levels for as much as 100K-plus miles before servicing is required. Same with carburetors. Electronic fuel injection is | + | This is similar to how the current ignition systems came to be. Kettering invented the points-type ignition system early in the last century and it endured for some 70 years. When it came time to clean up the environment, the OEM's switched to electronic ignition and we never looked back. Points-type ignitions have been replaced by HEI-type ignition systems. Now we have moved to solid state ignition with a coil for each cylinder, controlled by computers and rare earth spark plug electrodes to provide good performance and acceptable emissions levels for as much as 100K-plus miles before servicing is required. Same with carburetors. Electronic fuel injection is light years ahead of the old technology, and it contributes to vastly improved fuel mileage and much cleaner emissions. |
| − | For those | + | For those who insist on using flat tappet cams (more than likely due to the cost of roller units, particularly if building a pre-roller cam type of block), here is the best way to do it: |
1. Start with a matched and coordinated set of parts. Use the lifters and spring specs recommended by the cam grinder for your particular application and rpm limit. There is no point in using more valve spring pressure than needed, especially in a flat tappet street motor. To do so is asking for problems. Always consult with your favorite cam grinder for cam/lifter/spring recommendations for your particular application. Never rely solely on the recommendation of gearheads on auto forums. It's OK to ask and get general recommendations and suggestions from such sources, but before you lay down your hard-earned money, consult with the manufacturer's tech guy. He will want to know all the particulars of your combination including exact static compression ratio, so have all this written down so you can answer his questions intelligently. | 1. Start with a matched and coordinated set of parts. Use the lifters and spring specs recommended by the cam grinder for your particular application and rpm limit. There is no point in using more valve spring pressure than needed, especially in a flat tappet street motor. To do so is asking for problems. Always consult with your favorite cam grinder for cam/lifter/spring recommendations for your particular application. Never rely solely on the recommendation of gearheads on auto forums. It's OK to ask and get general recommendations and suggestions from such sources, but before you lay down your hard-earned money, consult with the manufacturer's tech guy. He will want to know all the particulars of your combination including exact static compression ratio, so have all this written down so you can answer his questions intelligently. | ||
| − | 2. | + | 2. You might want to research using special lifters or treatments that help prevent cam lobe/lifter failure. Some options are: |
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| − | You might want to research using special lifters or treatments that help prevent cam lobe/lifter failure. Some options are: | + | |
*Hard-faced lifters with a stellite face on the lifter crown that will resist scuffing. | *Hard-faced lifters with a stellite face on the lifter crown that will resist scuffing. | ||
*Comp Cams has an optional nitriding process that can be applied to any of their cams fr around $100 over he cost of the cam. | *Comp Cams has an optional nitriding process that can be applied to any of their cams fr around $100 over he cost of the cam. | ||
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3. There are specialty/racing motor oil that will give protection to your new cam and lifters. "Over the counter" motor oils are not up to the task, generally speaking and they are constantly changing formulations, it seems. Crane Cams has recommended Shell Rotella and an engine oil supplement containing extreme pressure lubricants. The other oil that is touted by engine builders is 15W-40 RPM Delo. GM has discontinued (and now have re-released) the EOS (Engine Oil Suppliment) they used to offer. If you use a molymndinum disulfide-type cam and lifter break in lube applied to the foot of the lifter and cam lobes along with good quality oil and add 1-1/2 ounces of ZDDP additive per quart of oil for initial startup, you've done as well as you can to prevent lifter/lobe scuff/wear/failure. With subsequent oil changes, one ounce per quart of oil should help to contribute to long engine life. | 3. There are specialty/racing motor oil that will give protection to your new cam and lifters. "Over the counter" motor oils are not up to the task, generally speaking and they are constantly changing formulations, it seems. Crane Cams has recommended Shell Rotella and an engine oil supplement containing extreme pressure lubricants. The other oil that is touted by engine builders is 15W-40 RPM Delo. GM has discontinued (and now have re-released) the EOS (Engine Oil Suppliment) they used to offer. If you use a molymndinum disulfide-type cam and lifter break in lube applied to the foot of the lifter and cam lobes along with good quality oil and add 1-1/2 ounces of ZDDP additive per quart of oil for initial startup, you've done as well as you can to prevent lifter/lobe scuff/wear/failure. With subsequent oil changes, one ounce per quart of oil should help to contribute to long engine life. | ||
| − | 4. Assemble your heads with old, used, '''stock''' springs if they will give enough lift before coil bind. DO NOT ASSEMBLE WITH THE SPRINGS YOU WILL EVENTUALLY RUN if the | + | 4. Assemble your heads with old, used, '''stock''' springs ''if they will give enough lift before coil bind''. DO NOT ASSEMBLE WITH THE SPRINGS YOU WILL EVENTUALLY RUN if the springs are much higher than about 120-130 pounds on the seat at the installed height. Keep an old set on the shelf just for running in a new motor, then change them out at the 30 minute mark. Manley makes a lever-type tool for this procedure, to be used with compressed air to keep the valve seated. If you don't have a compressor you can feed thin rope/cord down the spark plug hole with the piston down away from TDC. After the rope is fed in, carefully rotate the engine so the piston is compressing the rope up against the valve head. Do this on the compression stroke. Or have a shop do it. Another way is to use a set of reduced-ratio rocker arms for break-in. Crower Cams may have 1.2:1 ratio for SBC and 1.5:1 for BBC, but this needs to be researched. They may be high-buck roller units though, something that might be out of the reach of the home builder who only does one or two builds a year. Somebody needs to step up and make some stamped steel rockers in a reduced ratio that would be affordable for everyone. |
5. Checking for interference. Nothing will wipe a cam and lifters quicker than mechanical interference in the valvetrain. Check for piston to valve clearance, rocker arm to stud clearance at full lift, spring coil bind (stacking solid) and retainer to valve guide boss clearance at full lift. Also check for pushrod to guide clearance to insure the pushrods are not rubbing or binding. You might have one culprit that you didn't catch, such as a bent pushrod. Roll all pushrods on a piece of plate glass before assembly to insure straightness. See: [http://www.iskycams.com/camshaft.php Installing a Racing Camshaft] and [[Valve train points to check]]. | 5. Checking for interference. Nothing will wipe a cam and lifters quicker than mechanical interference in the valvetrain. Check for piston to valve clearance, rocker arm to stud clearance at full lift, spring coil bind (stacking solid) and retainer to valve guide boss clearance at full lift. Also check for pushrod to guide clearance to insure the pushrods are not rubbing or binding. You might have one culprit that you didn't catch, such as a bent pushrod. Roll all pushrods on a piece of plate glass before assembly to insure straightness. See: [http://www.iskycams.com/camshaft.php Installing a Racing Camshaft] and [[Valve train points to check]]. | ||
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:c. Use a hand held propane torch and heat the shaft to disperse any moisture. | :c. Use a hand held propane torch and heat the shaft to disperse any moisture. | ||
:d. Spray the cam with graphite. | :d. Spray the cam with graphite. | ||
| − | :e. Use quality high pressure lube on cam lobes and lifter crowns ( | + | :e. Use quality high pressure lube on cam lobes and lifter crowns (molybdenum disulfide black goop that comes with most cam and lifters). |
:f. Select a quality lifter since the market is being saturated with offshore lifters that are soft. | :f. Select a quality lifter since the market is being saturated with offshore lifters that are soft. | ||
:g. Make sure on startup the engine is ready to run at 2000-2500 rpm for 20 minutes. ZERO IDLING FOR 20 MINUTES. | :g. Make sure on startup the engine is ready to run at 2000-2500 rpm for 20 minutes. ZERO IDLING FOR 20 MINUTES. | ||
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