Can Someone Please Explain "Blue Printed" Heads?

When an engine is built, the manufacture specifies a "tolerance," or range, for the dimensions of its parts. Blueprinting means carefully measuring all these parts, and then if necessary machining them to make sure they're the best size or weight for performance.

For instance, a valve stem and a valve guide will be specified by the manufacturer with tolerances that allow for a clearance between them. If the clearance is too small, the valves may bind or stick, which can cause engine damage in some cases but will at the very least lead to a loss of performance due to the friction. If the clearance is too large, too much oil will flow down the valves into the cylinder and the spark plugs will foul. So "blueprinting" the valves and guides would involve carefully machining the valve guides to the BEST clearance, not just to whatever clearance happened to be there by picking a valve and a guide that were both "within tolerance."

Blueprinting is often used in conjunction with "balancing" an engine. The idea is very similar: balancing makes sure that all parts of the same kind have the same weight, down to very small tolerances. For example, a set of connecting rods may vary in weight; a balanced engine will measure the lightest connecting rod, then machine off tiny amounts of metal to make all the other rods in the engine have the same weight, down to a tenth of a gram. A balanced engine runs more smoothly, especially at high RPMs where an unbalance would be likely to cause extra wear on the internal components.

Scott F.

swest wrote: I would also add replacing the valve springs. They can test good but have issues while running. / :evil: Well worth the $65 for peace of mind.
Steve

neighbourdave wrote:

swest wrote: I would also add replacing the valve springs. They can test good but have issues while running. / :evil: Well worth the $65 for peace of mind.
Steve

APE directly from them or Z1

Where is a popular place / brand to get new springs?