[71CHEVYSHORTBED402]

Originally Posted by Rufas

I think you will find most cam manufactures recommend a zinc conventional oil for flat tappet cam break in. Zinc is not required on most of today's engines that are roller type tappets.

http://www.cranecams.com/whats_newview.php?s_id=36

http://howardscams.com/i-24078662-ho...-additive.html

http://www.hotrod.com/articles/ccrp-...ak-in-new-cam/

I didn't run oil with enough zinc additive in this 468 BBC with flat tappets. Cam went flat in less then 6,000 miles. It now has a roller cam in it.

When you say not enough Zinc, do you mean for the break-in period and/or ongoing? I used Zinc additive once. That link scared me off and I couldn't change the oil fast enough. Differences of opinions, and personally, I'm not settled on anything.

I can only speak for my 71 402 with 396 heads (larger ports). The engine was rebuilt in 93. I don't remember what oil we used, but I do recall changing it after say 500 miles. Soon after I used Valvoline Durablend only. Usually 10-40, but it really hummed on 20-50. I recently switched to Mobil 1 synthetic 5-30. Only tangible noticeable difference is the oil leaks nearly stopped. My engine sure liked that Durablend, but the gaskets didn't.

After we installed the motor we realized we didn't have a tach. "Too far" to any store, we took a dead highway on a straight line (beauty of Dayton Nevada) with steady acceleration, and guessed at the RPMs. Really, my bud and I were pretty comfortable with the situation.

There's now 40K on the engine. Purrs like a kitten, great response and power. The oil on the dipstick is always clear.