[Ron Sutton]

Originally Posted by GregWeld

Just my opinion - for what it's worth....


I've NEVER known a small block Chevy that ran with 45* advance.... and the more efficient the heads are - the LESS timing they require.

I've taken many EFI tuning classes - including those where the engine being tuned is on a dyno. It was demonstrated to us that FUEL RATIOS were relatively unimportant... affecting very little horsepower on the dyno from pig fat to too lean. What WAS important was as little as 2* of timing off optimal. The timing could affect as much as 40HP with just the slightest change. Remembering that horsepower is nothing more than a mathematical equation based off RPM and TORQUE... the torque is critically important to making a horsepower number.

Back in the day - during my drag racing years. We'd make a full throttle run - then pull the plugs (we used tow vehicles as I ran D/Gas). We'd then compare the MILES PER HOUR -- and read the plug strap. With the right timing - the miles per hour would improve - and the plug strap would change color right in the middle of the curve. That was a bingo. Now days we need a dyno to find this critical event.

Yup, Yup !

The more efficient the engine, the less timing it needs. I've had very efficient small blocks that made the most power with 32°. I've also had very in-efficient (but still 1100+ HP) mountain motors that needed 44° timing for optimum power.

And what Greg said ... 1°-2° off can be a big deal.