56J Motor, Recent Work & Lessons Learned

Posted by Joe Hall On 2013/12/1 12:42:04

Though I lurk here sometime, its been awhile since I'd had anything worth posting. But a recent experience with the 352 in my beloved 56J may be worth mentioning.

I have owned this 56J since 1986, at 81,000 miles. It now has around 235,000 miles, so have first hand history.

I had rebuilt the short block over 90,000 miles ago, and the heads over 120,000 miles ago (included hardened exhaust seats), in the 1980s-90s.
Over the past few years and 10,000-15,000 miles, the 352 had progressively became ill: lost pep, lost MPG, ran at lower vacuum, and recently would only wind up to around 3500 RPM before valve float, so I decided to investigate.

About 15,000 miles ago, I had installed a newly reground (Effingham)cam and new set of (Terrell)lifters. Upon run-in, I noticed some of the pushrods were barely turning. On the several other 352s I have had, they usually spin at not more than 10 seconds per rotation. A recent inspection before teardown of this 352 revealed several of the lifters were not rotating at all. So, I figured in addition to normal wear & tear, it had a cam problem.

Upon teardown, the lifter bottoms were shot: one had a groove worn straight across it, and most of the others had a splotched wear pattern instead of circular. (Indicative of not enough spin.) The cam also had a weird wear pattern.

So, I had Jack V. send me a reground cam. After install of Jack's cam and another new set of Terrell lifters, the pushrods spun similar to the Effingham cam. So, thinking maybe I'd gotten some offshore lifters, I had Jack send me a set of (Johnson) USA lifters. Installed those with same, disappointing results.

So, after two cams and three sets of lifters, I figured it had to be something else.

Long story short, I figured out 14 of the 16 pushrod sockets in the rockers were shot. I replaced those rockers, and flipped all the pushrods upside down. The pushrods now rotate as they should.

Footnote: the heads were toast, but the bottom end looked great, and it still gets over 4000 per quart of oil. So with a fresh set of heads, cam, lifters, and rockers, I figure this 352 is good for another 100,000 miles :)