Setting Valve Lash
This is the ONLY acceptable technique for adjusting valves. Work cylinder by cylinder. Turn engine until exhaust valve just breaks open, then adjust intake valve. Open intake valve all the way to max. lift and on until almost closed, then adjust the exhaust valve. Mark each rocker that is set so none is missed. Setting lash any other way (TDC method or two rollover method) may put lifter on a clearance ramp and cause misadjustment, costing you power at a minimum and risking possible engine damage.
Note: Lash spec for a camshaft is not a starting point, it is a MAXIMUM. Adjustment can be tighter, but no more than .002 on tight lash cams normally. If lash is set cold, set .002 tight on iron heads, .003 tight for aluminum heads, and .006 tight for an all aluminum motor as an initial setting. ALWAYS RECHECK at operating temperature.
Tip: Figure the exact correction factor for each valve as it shrinks to cold and you can then set cold and know exactly what it will warm up to. Measure all valves hot and document, let engine cool, recheck and you can calculate how much each one changes and then set cold lash to correct growth setting. Notice how they are not the same setting cold on each valve as the expansion is different on different parts of the head.
Check spring pressures and document on the spring sheet I supply weekly.
Other important information
Intake Manifold torque – Intake manifold leaks are the number ONE cause for lean conditions, causing blown head gaskets, burned pistons, spark plug tip melting, and numerous tuning problems.
Re-torque your manifold frequently, small block Chevy 25-30 pounds.
Most common area for leak is at the bottom side of intake ports. To check remove carb and look down ports. If any look glossy down the runner with a flashlight, that is the oil coming up through gasket from the lifter valley.
If the manifold is removed for any reason DO NOT put on without sealer on the gasket. Duplicate the way we installed it using 3M weather strip adhesive and silicone.
Carb Spacers – Always use plastic or phenolic spacers as a temperature barrier because the less temperature the carb changes the more consistent the fuel curve for mixture control.
Air Cleaners – KEEP FILTERS CLEAN. A clean air filter is free horsepower! Having good filters with an inferior base seal is counter productive. The ones that come with the K & N kits are not good enough to use at all. We stock an air cleaner gasket with rubber on both sides with a steel girdle in the center. It will virtually last forever.
If the air filter element is collapsed in any way (even a little bit) it will not seal properly and needs to be replaced.
If your class allows air boxes use them! Box off hood to pull air from the topside of the hood, air under the hood is heated and less dense, cool air above hood is MORE horsepower.