How to rebuild an engine
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− | + | Hi fellows, I'm the old techinspector1 here to share some information with you about oils, flat tappet camshafts and break-in procedures for them. The following is copied from a post I wrote for another auto enthusiast forum where we were talking about the oil companies changing oil formulations and the resultant flat tappet camshaft failures we have experienced as a result. | |
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+ | Fellows, we are the victims of technology marching on. 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. The oil companies have no choice, they have to bow to pressure from the powers that be. | ||
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+ | I don't see this as being any different than points-type ignitions. Kettering invented the 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. Now we have moved to solid state ignition with a coil for each cylinder, controlled by computers. Same with carburetors. Electronic fuel injection is light years ahead of the old technology, contributes to vastly improved fuel mileage and much cleaner emissions. | ||
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+ | The only cure-all that I see is a change to roller cams. The old flat tappet technology is just about dead, save for a few of us old die-hards. | ||
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+ | For those of you who insist on using flat tappet cams (more than likely due to the cost of roller units), I will herein give my take on the best way to do it. | ||
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+ | 1. Start with a matched and coordinated set of parts from ONE SOURCE, buying the springs recommended by the cam grinder for your particular application and rpm limit. There is no point in using Gorilla springs in a street motor. You're just asking for it. | ||
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+ | 2. Discuss using armored lifters with the tech person at your favorite grinder. These have a stellite face on the lifter crown that will resist scuffing. By the way, I often read posts by those who are building motors that they made a great deal on a cam and lifter set. There is no such thing as a "great deal" on cam and lifters. Little do they know that this is junk made offshore and that they will be buying a new set of cam and lifters shortly, as well as spending a few days tearing the motor completely apart to clean out the shrapnel. Yep, it was a great deal though. You might want to buy a set of these with the "great deal" cam and lifters.... | ||
+ | http://www.moroso.com/catalog/catego...?catcode=27006 | ||
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+ | 3. Oil.... From what I've read, there are only a couple of oils left that will give protection to your new cam and lifters and even they are changing formulations as we speak. Crane Cams recommends Shell Rotella and an engine oil supplement containing extreme pressure lubricants such as General Motors EOS. The other oil that is touted by engine builders is 15-40 RPM Delo. | ||
+ | http://www.shell.com/home/Framework?...ellamulti.html | ||
+ | http://www.sdparts.com/product/10523...6ozBottle.aspx | ||
+ | I've used GM EOS on every rebuild I've done except one and I wiped a lobe on that motor. Another additive that has been mentioned is Valvoline Synpower Oil Treatment. I've never used it, but it is said to have moly, boron, calcium, magnesium, phosphorus and zinc added to it. Sounds like a good multi-vitamin doesn't it. | ||
+ | http://www.valvoline.com/pages/produ...asp?product=21 | ||
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+ | 4. Assemble your heads with old, used --STOCK-- springs. DO NOT ASSEMBLE WITH THE SPRINGS YOU WILL EVENTUALLY RUN. I keep an old set on the shelf just for running in a new motor, then change them out at the 30 mile mark. Manley makes a lever-type tool for this procedure, to be used with shop air to keep the valve seated. Don't have shop air?? Change them out at a buddies house or have the machine shop do it. What's that you say, you don't want the hassle of changing out the springs?? O.K., suffer the alternative then. | ||
+ | http://www.jegs.com/webapp/wcs/store...48285_-1_10797 | ||
+ | The other way is a set of reduced-ratio rocker arms for break-in. I've heard that Crower Cams makes some 1.2:1 for SBC and 1.5:1 for BBC, but am unable to find them in Crower's catalog. I suspect they would 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 need to step up and make some stamped steel rockers in a reduced ratio that would be affordable for everyone. | ||
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+ | 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 they are not rubbing and 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. | ||
+ | http://www.iskycams.com/camshaft.php | ||
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+ | 6. R. Pope brings an excellent point to the fore, tight lifter to bore fitment. I don't know about the rest of you, but I always oil the lifter bores and lifters when doing mock-up and drop them through the lifter bores. With the lifter bores vertical on the engine stand, the lifters should drop through and fall into your hand with oil on them. If they don't, hone the bores for another 0.001" of clearance. I'm told that the cam grinders are beginning to manufacture their lifters with a shorter radius on the crown to assist in lifter rotation. I'm recalling from memory and may be wrong, but I'm thinking that the traditional radius that has been used is 50". Maybe they're reducing that to 40" or 30". I'm just supposing and don't know for sure. | ||
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+ | 7. These suggestions are brought to you by John Callies of Callies Crankshaft fame. | ||
+ | a.visual inspect for tool chatter and mis-machining. | ||
+ | b.clean the shaft with mineral spirits and dry thoroughly. | ||
+ | c.use a hand held propane torch and heat the shaft to dispurse any moisture. | ||
+ | d.spray the cam with graphite. | ||
+ | e.use quality high pressure lube on cam lobes and lifter crowns (Molybdenum Disulfide black goop that comes with the cam and lifters). | ||
+ | f.select a quality lifter since the market is being saturated with off shore 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. | ||
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+ | 8. Make sure the motor is timed and use a known good carb or other induction system as well as ignition system. THE NEW CAM AND LIFTERS WILL NOT TOLERATE ANY GRINDING ON THE STARTER TO GET THE MOTOR FIRED. THEY ARE LUBED BY SPLASH OFF THE CRANK AT HIGHER ENGINE SPEEDS. HAVE EVERYTHING READY TO GO INCLUDING HAVING THE CARB PRIMED WITH FUEL. | ||
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+ | 9. Pre-oil the motor with a drill motor and oil pump primer tool such as this one from Jegs... | ||
+ | http://www.jegs.com/webapp/wcs/store...54806_-1_10455 | ||
+ | Put a socket on the harmonic damper retaining bolt and rotate the motor through at least 2 full revolutions while priming. | ||
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+ | 10. At the end of your 20 minute break-in period, drop the oil and filter and change them out. Use another bottle of GM EOS in the oil. Drive the vehicle for 30 miles, altering the speed and letting the motor rev down from 60 mph to 20 mph with your foot off the gas pedal. Drop the oil and filter and repeat the EOS again. Change the valve springs. Drive for 500 miles and drop the oil and filter again. | ||
+ | __________________ | ||
+ | techinspector1 | ||
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The best advice is get somebody more experienced with engine assembly and learn from them since trying to do it alone could be a recipe for disaster especially since you have spent all that time and money getting to this stage. There are a whole lot of little hints and signs that to a novice don't mean a thing and you just go on not realizing that something has happened that will cause you engine not to run correctly or worse. Check, check and recheck everything...take nothing for granted! | The best advice is get somebody more experienced with engine assembly and learn from them since trying to do it alone could be a recipe for disaster especially since you have spent all that time and money getting to this stage. There are a whole lot of little hints and signs that to a novice don't mean a thing and you just go on not realizing that something has happened that will cause you engine not to run correctly or worse. Check, check and recheck everything...take nothing for granted! |