Need for calibrated tools, gauges etc.
Posted: Fri Apr 21, 2006 12:00 pm
I have often mentioned the necessity of using calibrated measuring tools when assembling/testing an engine. For the V6 build, I ordered and got from Speedway a valve spring tester and I checked and paired the new Arricambi springs I got. The readings were good, but a bit high compared to the published specs (~12-15lbs higher). It turned out that with the available installed height (IH) I have, spring pressure would be too high. Visions of worn cam lobes, had me scouring for alternate springs and I did find a set with the correct pressures. Long time ago, I had measured another V6 sring set again from Arricambi and it was smack on spec. Curious about this, I took two springs to work and measured them on two of the calibrated testers we have there. Brought the curves home and sure enough, my tester was reading high. I used the correct curves to adjust it so it now reads the same with the others. Well, the previously 'unsuitable' springs are ok for use with std weight valves and if trick retainers are used (allowing for more IH) their pressure can be lowered for use with lightweight valves.
The moral of the story is to use calibrated tools/gauges and if not, to know how 'wrong' your tools are. Compression gauges, torque wrenches, spring testers and all car instruments-speedo, tach, oil press. gauge, water temp gauge. All these can be calibrated, some in conjunction with their senders. I really want to know my true speed and laugh when other guys can't decide whether its their speedo, tach or both that are wrong! Maybe I'm paranoid, but I had to recalibrate the speedo when I switched from 15 to 16" wheels (from 205/50-15 to 205/50-16) Maybe its 'trivial pursuit' but press. gauges that read zero at idle are a sore sight I'm sure!
Jim K.
The moral of the story is to use calibrated tools/gauges and if not, to know how 'wrong' your tools are. Compression gauges, torque wrenches, spring testers and all car instruments-speedo, tach, oil press. gauge, water temp gauge. All these can be calibrated, some in conjunction with their senders. I really want to know my true speed and laugh when other guys can't decide whether its their speedo, tach or both that are wrong! Maybe I'm paranoid, but I had to recalibrate the speedo when I switched from 15 to 16" wheels (from 205/50-15 to 205/50-16) Maybe its 'trivial pursuit' but press. gauges that read zero at idle are a sore sight I'm sure!
Jim K.