3
370HP LT-1
Guest
Valve adjustment is not an easy task for the first time mechanic. The problem with the LT-1 and all other stock Chevy motors is that there are no refrence pionts on the harmonic balancer for cylinders other than the #1 cylinder. You need to know where the engine is in the firing order to correctly adjust the valves if they are done incorrectly the best case scenario is the engine runs very rough with back firing and in the worse case scenario there is severe mechanical damage to the valves and valvetrain assemblies causing a teardown of the engine to be required.
With these warnings I am going to decribe to you some ways to do a proper valve adjustment. Technique #1 is to get an old distributor cap and cut off the top of the cap and use the ignition rotor as a firing cylinder reference to adjust the valve of the cylinder that is firing (check for lash at both rocker arm assemblies to insure that the cylinder is at TDC on the firing stroke) or you can adjust the previous cylinder's intake valve and the next firing cylinder's exhaust valve (Example if the rotor is on #1 cylinder you would adjust cylinder #2 intake and cylinder #8 exhaust valve then rotate the distributor to #8 cylinder and adjust #1 intake valve and #4 exhaust valve). Method #2 is to get a cheap piece of junk called a MR Gasket Timing Tape (about $10) for your 8" diameter harmonic balancer and after cleaning your balancer with brake parts cleaner or lacquer thinner (a miserable messy job best done from underneath the LT-1), and sucessfully affixing the tape (easier said than done) you can then start adjusting the valves from the harmonic balancer refrence marks on the timing tape. You would adjust #1intake and exhaust valves at #1TDC mark then go on to #8TDC mark #4, #3, then when you get back to the previous #1TDC mark you are actually on #6 TDC (it is easy to get confused but you should always be able to feel valve lash at the rocker arms when the cylinder is at TDC during the firing stroke). I use the harmonic balancer method on my 72 LT-1 that has an aftermarket camshaft (Ultra-dyne the only way to FLY!) but I also have a fullly degreed aftermarket harmonic balancer (explosion proof for those 7500RPM upshifts at the autoX races). You can also do the math and figure the radial length of the 8"dia harmonic balancer by multiplying the diameter (8.0") by PI (3.141) = 25.132 circumfrence length, divide that by 4 = 6.283 (close enough to
6 1/4" in length) and steal your wifes sewing mesuring tape to mark off your balancer refrence marks for all four cylinders TDC on the balancer (if you really want to make you wife happy put the tape back into the sewing chest without cleaning it, she'll love that!). The balancer is most easily marked with chalk or a felt pen (you don't have to clean it when using chalk!). I hope I have helped you and not just lead to further confusion on this supject, if you have any questions please Email me at: LTdash1@home.com
Good Luck, Eric Brandt
With these warnings I am going to decribe to you some ways to do a proper valve adjustment. Technique #1 is to get an old distributor cap and cut off the top of the cap and use the ignition rotor as a firing cylinder reference to adjust the valve of the cylinder that is firing (check for lash at both rocker arm assemblies to insure that the cylinder is at TDC on the firing stroke) or you can adjust the previous cylinder's intake valve and the next firing cylinder's exhaust valve (Example if the rotor is on #1 cylinder you would adjust cylinder #2 intake and cylinder #8 exhaust valve then rotate the distributor to #8 cylinder and adjust #1 intake valve and #4 exhaust valve). Method #2 is to get a cheap piece of junk called a MR Gasket Timing Tape (about $10) for your 8" diameter harmonic balancer and after cleaning your balancer with brake parts cleaner or lacquer thinner (a miserable messy job best done from underneath the LT-1), and sucessfully affixing the tape (easier said than done) you can then start adjusting the valves from the harmonic balancer refrence marks on the timing tape. You would adjust #1intake and exhaust valves at #1TDC mark then go on to #8TDC mark #4, #3, then when you get back to the previous #1TDC mark you are actually on #6 TDC (it is easy to get confused but you should always be able to feel valve lash at the rocker arms when the cylinder is at TDC during the firing stroke). I use the harmonic balancer method on my 72 LT-1 that has an aftermarket camshaft (Ultra-dyne the only way to FLY!) but I also have a fullly degreed aftermarket harmonic balancer (explosion proof for those 7500RPM upshifts at the autoX races). You can also do the math and figure the radial length of the 8"dia harmonic balancer by multiplying the diameter (8.0") by PI (3.141) = 25.132 circumfrence length, divide that by 4 = 6.283 (close enough to
6 1/4" in length) and steal your wifes sewing mesuring tape to mark off your balancer refrence marks for all four cylinders TDC on the balancer (if you really want to make you wife happy put the tape back into the sewing chest without cleaning it, she'll love that!). The balancer is most easily marked with chalk or a felt pen (you don't have to clean it when using chalk!). I hope I have helped you and not just lead to further confusion on this supject, if you have any questions please Email me at: LTdash1@home.com
Good Luck, Eric Brandt
