Basic modifications for newbies
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I'm just throwing these numbers around to show you that the cam in the Super Comp motor will not work in your street-driven 350 Chevy. The Thumpr cam may work, but you may be able to make more horsepower and torque by matching the other motor characteristics to the proper camshaft and still have your rump-rump. | I'm just throwing these numbers around to show you that the cam in the Super Comp motor will not work in your street-driven 350 Chevy. The Thumpr cam may work, but you may be able to make more horsepower and torque by matching the other motor characteristics to the proper camshaft and still have your rump-rump. | ||
| − | I've gotten a little off track with my explanation. We need to go back to what a newbie should do to his vehicle FIRST. | + | I've gotten a little off track with my explanation. We need to go back to what a newbie should do to his vehicle FIRST. |
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After rebuilding the brakes, steering and suspension the first modification done to an otherwise stock auto/truck should usually be a different gear ratio. A good compromise between mileage and acceleration in a street car is somewhere around 3.70:1 ratio. If the owner intends to change this vehicle into a semi-serious street/drag car, then additional aftermarket traction devices such as anti-wheel hop products and tires with different rubber compound should be considered, along with strengthening and stiffening the chassis/body. Even more serious competitors should consider mini-tubs or full tubs in the car to accommodate wide racing slicks, along with a roll cage to tie the chassis together better. A large number of racers who show up at my track mount slicks on separate wheels (wide steel wheels will work just fine) to be bolted to the car after they drive it in off the street. | After rebuilding the brakes, steering and suspension the first modification done to an otherwise stock auto/truck should usually be a different gear ratio. A good compromise between mileage and acceleration in a street car is somewhere around 3.70:1 ratio. If the owner intends to change this vehicle into a semi-serious street/drag car, then additional aftermarket traction devices such as anti-wheel hop products and tires with different rubber compound should be considered, along with strengthening and stiffening the chassis/body. Even more serious competitors should consider mini-tubs or full tubs in the car to accommodate wide racing slicks, along with a roll cage to tie the chassis together better. A large number of racers who show up at my track mount slicks on separate wheels (wide steel wheels will work just fine) to be bolted to the car after they drive it in off the street. | ||
| − | See [http://www.crankshaftcoalition.com/wiki/Why_a_shorter_rear_gear_will_accelerate_the_car_quicker Why a shorter rear gear will accelerate the car quicker] | + | See [http://www.crankshaftcoalition.com/wiki/Why_a_shorter_rear_gear_will_accelerate_the_car_quicker Why a shorter rear gear will accelerate the car quicker] for more on this subject. |
Of course, when it comes to traction, a limited slip differential like the Chevrolet Posi-Traction or aftermarket Detroit Locker or Auburn units or similar units will do an excellent job of hooking up both tires. However, these are not mandatory to get both tires to pull and not spin the passenger side tire. | Of course, when it comes to traction, a limited slip differential like the Chevrolet Posi-Traction or aftermarket Detroit Locker or Auburn units or similar units will do an excellent job of hooking up both tires. However, these are not mandatory to get both tires to pull and not spin the passenger side tire. | ||
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'''DISCLAIMER:''' THE FOLLOWING INFORMATION WAS GLEANED FROM MANY DIFFERENT SOURCES. SOME OF IT MAKES SENSE TO ME AND SOME OF IT DOESN'T. USE WHAT YOU THINK IS REAL AND THROW OUT THE REST OF IT. I HAVE NOT USED ALL OF THE SUGGESTIONS LISTED HERE. THROUGH THE YEARS, I HAVE ACCOMPLISHED MANY SUCCESSFUL FLAT TAPPET CAMSHAFT BREAK-INS, BUT I HAVE ALSO ROACHED A FEW. USE THIS LIST AS A GUIDELINE SO THAT YOU REMEMBER TO CHECK ALL THESE THINGS WHEN INSTALLING A NEW FLAT TAPPET CAMSHAFT. DO NOT TAKE EVERYTHING POSTED HERE AS GOSPEL. IF THE MANUFACTURER OF THE CAMSHAFT YOU'RE USING RECOMMENDS PROCEDURES THAT DIFFER FROM WHAT IS SHOWN HERE, USE THE MANUFACTURER'S RECOMMENDATIONS TO THE LETTER AND DISREGARD THIS INFORMATION. | '''DISCLAIMER:''' THE FOLLOWING INFORMATION WAS GLEANED FROM MANY DIFFERENT SOURCES. SOME OF IT MAKES SENSE TO ME AND SOME OF IT DOESN'T. USE WHAT YOU THINK IS REAL AND THROW OUT THE REST OF IT. I HAVE NOT USED ALL OF THE SUGGESTIONS LISTED HERE. THROUGH THE YEARS, I HAVE ACCOMPLISHED MANY SUCCESSFUL FLAT TAPPET CAMSHAFT BREAK-INS, BUT I HAVE ALSO ROACHED A FEW. USE THIS LIST AS A GUIDELINE SO THAT YOU REMEMBER TO CHECK ALL THESE THINGS WHEN INSTALLING A NEW FLAT TAPPET CAMSHAFT. DO NOT TAKE EVERYTHING POSTED HERE AS GOSPEL. IF THE MANUFACTURER OF THE CAMSHAFT YOU'RE USING RECOMMENDS PROCEDURES THAT DIFFER FROM WHAT IS SHOWN HERE, USE THE MANUFACTURER'S RECOMMENDATIONS TO THE LETTER AND DISREGARD THIS INFORMATION. | ||
| − | *1. Failure to remove all | + | *1. Failure to remove all rust preventative from cam and lifters with solvent once you get them home. (This advice does not include removing coatings applied at the factory such as phosphates. It is only suggesting to remove rust preventative grease that may or may not have been applied to the cam/lifters to prevent rust in storage. This grease will not have the extreme pressure characteristics that molybdenum disulphide (moly) break-in lube has and should be removed so that moly break in lube can be applied properly. Moly break-in lube is sometimes black, usually thick extreme-pressure grease that is recommended by camshaft manufacturers to be applied to the lifter crowns/cam lobes for initial camshaft break-in. It's usually supplied with the camshaft, but if it isn't, it must be bought separatly and used. |
| − | *2. Failure to wash the cam and lifters with hot soapy water to remove the remainder of rust | + | *2. Failure to wash the cam and lifters with hot soapy water to remove the remainder of rust preventative that wasn't removed with solvent, and to give the cam a final wash. CAUTION; WASH ONLY THE CROWN OF THE LIFTERS (THE VERY BOTTOM OF THE LIFTER WHERE IT CONTACTS THE CAMSHAFT LOBE). DO NOT ALLOW WATER TO GET INTO THE INTERIOR OF THE LIFTER BODY. BE VERY CAREFUL HERE IF THE LIFTER HAS AN OILING HOLE THAT HAS BEEN EDM'D INTO THE CROWN TO PROVIDE OIL FROM THE INTERIOR OF THE LIFTER BODY TO THE CAMSHAFT LOBE. Dry the cam and lifter crowns thoroughly with hot air from a hot air gun or hair dryer to remove all traces of moisture before applying molybdenum disulfide break-in lube. |
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| + | {{warning|DO NOT USE ANY ABRASIVE MATERIALS SUCH AS SCOTCHBRITE PADS OR SANDPAPER OF ANY KIND TO ACCOMPLISH THESE SOLVENT AND SOAP CLEANING OPERATIONS. USE ONLY SOFT, CLEAN RAGS. THE WHOLE INTENT OF CLEANING THE CAMSHAFT IS SO THAT WE CAN REMOVE RUST-PREVENTATIVE OILS AND GREASES THAT MIGHT HINDER GETTING DOWN TO THE BASE METAL IN ORDER TO PERFORM OPERATION #3 SHOWN HERE.}} | ||
*3. Failure to properly massage an extreme pressure lubricant such as Molybdenum Disulfide into the pores of the metal on all lobes and lifter faces. Moly will actually bond with the metal and give maximum protection to the lifter crown/lobe. | *3. Failure to properly massage an extreme pressure lubricant such as Molybdenum Disulfide into the pores of the metal on all lobes and lifter faces. Moly will actually bond with the metal and give maximum protection to the lifter crown/lobe. | ||
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*10. Failure to run the motor at high rpm (2500 or higher, alternating 1000 rpm up and/or down to allow the crank to throw oil in different places at different revs) for the first 40-45 minutes of its life. NO IDLING. NO IDLING. NO IDLING. The motor should not be run at less than 2500 rpm for a minimum of 40 minutes. If a problem develops, shut the motor down and fix it, then resume break-in. The main source of camshaft lubrication is oil thrown off the crankshaft at speed, drainback from the oil rings and oil vapors circulating in the crankcase. At idle, the crank isn't spinning fast enough to provide sufficient oil splash to the camshaft/lifters for proper break-in protection. | *10. Failure to run the motor at high rpm (2500 or higher, alternating 1000 rpm up and/or down to allow the crank to throw oil in different places at different revs) for the first 40-45 minutes of its life. NO IDLING. NO IDLING. NO IDLING. The motor should not be run at less than 2500 rpm for a minimum of 40 minutes. If a problem develops, shut the motor down and fix it, then resume break-in. The main source of camshaft lubrication is oil thrown off the crankshaft at speed, drainback from the oil rings and oil vapors circulating in the crankcase. At idle, the crank isn't spinning fast enough to provide sufficient oil splash to the camshaft/lifters for proper break-in protection. | ||
| − | *11. Failure to clearance lifters in their bores so that they spin freely. Lifter clearance should be 0.0012" to 0.002", with 0.0015" (one and one | + | *11. Failure to clearance lifters in their bores so that they spin freely. Lifter clearance should be 0.0012" to 0.002", with 0.0015" (one and one half thousandths) considered close to ideal. Too loose is as bad as too tight. |
| − | *12. Failure to initially adjust the valves properly. Using the "spin the pushrod until it feels tight" method will normally result in valves too tight. With both valves closed and the piston at TDC on the compression/firing stroke for that cylinder, hold the tip of one rocker arm down tightly against the valve stem with one hand and jiggle the pushrod up and down with the thumb/forefinger of your other hand until all play between the pushrod and the other end of the rocker arm is removed, then turn the rocker nut 1/2 to 3/4 turn to set the preload. Now, do the same thing on the other rocker arm/pushrod for that cylinder. The bulletproof way to adjust valves is this method just described. Beginning on the #1 cylinder and following the firing order, you can adjust the intake and exhaust rockers for each cylinder as you turn the crank 1/4 turn at a time. In other words, on a Chevy, bring the piston of #1 cylinder (front, driver's side) up to top dead center on the compression/firing stroke. Both valves will be closed and the intake and exhaust lifters will be on the heel of the camshaft at that point, so you can adjust both the intake and exhaust rockers for that particular cylinder at the same time. Turn the crankshaft 1/4 turn clockwise and adjust the intake and exhaust rockers on #8 cylinder (rear, passenger side). It is the next cylinder in the firing order after #1. After you have adjusted both the intake and exhaust rockers for #8 cylinder, turn the crankshaft clockwise another 1/4 turn. That will put the piston of #4 cylinder (second from front, passenger side) at top dead center and you can adjust both intake and exhaust rockers for that cylinder. Following this, turn the crankshaft another 1/4 turn and adjust intake and exhaust rockers on cylinder #3 (second from front, driver's side). Another 1/4 turn and adjust both on cylinder #6 (third from front, passenger side), another 1/4 turn and adjust both on cylinder #5 (third from front, driver's side), another 1/4 turn and adjust both on cylinder # 7 (rear, driver's side) and finally, another 1/4 turn and adjust both on cylinder #2 (front, passenger's side). This routine will work on any motor if you start out on #1 and follow the firing order, turning the crank 1/4 turn in between adjustments to move on to the next cylinder in the firing order. Be careful on Fords, they have a different cylinder numbering system and several different firing orders, depending on the engine family. | + | *12. Failure to initially [http://www.crankshaftcoalition.com/wiki/Adjusting_hydraulic_lifters adjust the valves] properly. Using the "spin the pushrod until it feels tight" method will normally result in valves too tight. With both valves closed and the piston at TDC on the compression/firing stroke for that cylinder, hold the tip of one rocker arm down tightly against the valve stem with one hand and jiggle the pushrod up and down with the thumb/forefinger of your other hand until all play between the pushrod and the other end of the rocker arm is removed, then turn the rocker nut 1/2 to 3/4 turn to set the preload. Now, do the same thing on the other rocker arm/pushrod for that cylinder. The bulletproof way to adjust valves is this method just described. Beginning on the #1 cylinder and following the firing order, you can adjust the intake and exhaust rockers for each cylinder as you turn the crank 1/4 turn at a time. In other words, on a Chevy, bring the piston of #1 cylinder (front, driver's side) up to top dead center on the compression/firing stroke. Both valves will be closed and the intake and exhaust lifters will be on the heel of the camshaft at that point, so you can adjust both the intake and exhaust rockers for that particular cylinder at the same time. Turn the crankshaft 1/4 turn clockwise and adjust the intake and exhaust rockers on #8 cylinder (rear, passenger side). It is the next cylinder in the firing order after #1. After you have adjusted both the intake and exhaust rockers for #8 cylinder, turn the crankshaft clockwise another 1/4 turn. That will put the piston of #4 cylinder (second from front, passenger side) at top dead center and you can adjust both intake and exhaust rockers for that cylinder. Following this, turn the crankshaft another 1/4 turn and adjust intake and exhaust rockers on cylinder #3 (second from front, driver's side). Another 1/4 turn and adjust both on cylinder #6 (third from front, passenger side), another 1/4 turn and adjust both on cylinder #5 (third from front, driver's side), another 1/4 turn and adjust both on cylinder # 7 (rear, driver's side) and finally, another 1/4 turn and adjust both on cylinder #2 (front, passenger's side). This routine will work on any motor if you start out on #1 and follow the firing order, turning the crank 1/4 turn in between adjustments to move on to the next cylinder in the firing order. Be careful on Fords, they have a different cylinder numbering system and several different firing orders, depending on the engine family. |
*13. Failure to inspect the distributor drive gear for wear. Too much wear can allow the cam to walk in its cam bore and allow a lobe to contact an adjacent lifter. | *13. Failure to inspect the distributor drive gear for wear. Too much wear can allow the cam to walk in its cam bore and allow a lobe to contact an adjacent lifter. | ||
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*16. Failure to use new lifters on a used cam. Used lifters should only be used on the very same cam, in the very same block and in the very same positions they were removed from. Chances that the lifter bores will be machined on the very same angles on a different block as the block the lifters came out of are about equal to you hitting the lottery. | *16. Failure to use new lifters on a used cam. Used lifters should only be used on the very same cam, in the very same block and in the very same positions they were removed from. Chances that the lifter bores will be machined on the very same angles on a different block as the block the lifters came out of are about equal to you hitting the lottery. | ||
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*Just a note to make you aware of the loading between the camshaft lobe and lifter crown. That pencil-point of contact, if carried out to a square inch, would be somewhere between 250,000 and 300,000 POUNDS PER SQUARE INCH. | *Just a note to make you aware of the loading between the camshaft lobe and lifter crown. That pencil-point of contact, if carried out to a square inch, would be somewhere between 250,000 and 300,000 POUNDS PER SQUARE INCH. | ||
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| − | == | + | ==Resources== |
| − | [[Valve Train Points To Check]] | + | *[http://www.crankshaftcoalition.com/wiki/Chevrolet_engine_rebuild_guide_books_and_DVDs Books and DVDs.] |
| + | *[[Valve Train Points To Check]] | ||
| + | *[[Category:General hotrodding]] | ||
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[[Category:General hotrodding]] | [[Category:General hotrodding]] | ||
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