Thread: 305 heads junk?

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eric, please read this blurb from HPC Research.....

Take a Vice. Most any vice. Install a protective covering over the teeth of the Vice. Push wrist pin out of Piston until 2/3 of the wrist pin is sticking out. Stick the section that's sticking out into the covered jaws of the vice. Snug jaws of Vice around Wrist pin. Place one "leg" of a Carpenter's Square or equivalent on the table where the Vice is. Place the other "leg" of the Square up against the side of the Piston. (Adjust the Piston if necessary). Without moving the Square, Rotate the piston until the OTHER side of the Piston is facing the Square. Note that there is now a noticeable "gap" between the leg of the Square and the Piston. That "gap" is a measure of the "offset". (Actually, the gap is TWICE the wrist pin "offset", and it is left to the Student to prove why this is so.) Oh, so when you rotated the Piston, the Piston moved the Square back a little? No problem. Line the Square up again against the side of the Piston. Then Rotate the piston until the other side of the Piston is facing the Square. NOW, note the "gap". When you see the "gap", that side of the Piston is the one where the Wrist Pin is closest. (Think of the "offset" as increasing or decreasing the angle of the "lever" arm of the Connecting Rod on the Crankshaft. (Some Formula V racers purposely put their VW pistons in backwards- to INCREASE the Lever arm and Torque- piston slap be damned- especially if you win the race.) A Tip o' the Maestro's Hat to Mr. Stoddard for this simple but effective, handy-dandy little homemade tool to measure piston "offset".

(The diagram didn't come out right, but all it entails is using a carpenter's square stood on edge and up against the skirt with a reference on the table for the square to butt against.)