Ping at cruise speed

Thrust surface:

So I finally got some space in the garage cleared and all the accessories removed from the engine. I have the a/c compressor suspended from a wood board with some tie wire so I don't have to unhook the likes and, er, properly evacuate the refrigerant. I hope to unhook the transmission and exhaust pipes tonight and pull the engine tomorrow morning.

The teardown begins. I wonder if this crack in the passenger side exhaust manifold has something to do with my original noise complaint. There are a few other small cracks on both manifolds, but this is the one I can find that I can also see the back side of.

I figured I'd need to cut the "trumpet horns" off the front ends of the exhaust pipes, and then clamp on the header collector flanges, but I'm hoping for a minimum beyond that at least for now. I was thinking headers since I need to swap anyway, so I might as well pick up a few horsepower. Shorty because I have a 351C-2V and a C6 transmission, and long-tube headers that fit that combo aren't readily available. I want to keep the current exhaust pipes because I got laid off from my job, which gives me more time to work on the car but limits cash for car stuff that's not really needed. Manifold is cracked, so that's a need, but pipes and mufflers are fine, so not a need.

Inkara1 wrote: Found a set of manifolds in great condition on eBay, so I bought them. Question: if the passenger side manifold is prone to cracking, are there any steps I can take to keep the "new" one from also cracking? Anything I need to avoid happening to it?

Inkara1 wrote: On the oil pump, the pickup won't stay level. I can screw it in around 7 turns, but where it comes to a hard stop, I'd need another 1/2 turn to have it the right direction, so instead I have to back it off 1/2 turn. But then if the engine is upside-down on the stand, the pickup will move until it's resting on the crankshaft, and with the engine right-side up, it'll turn until it's either all the way down or until the oil pan stops it if it's on. It's still in 6 to 6 1/2 turns, but I've heard it can still suck air through the threads. I tried some Permatex thread sealer in lieu of teflon tape, but it was still loose. Will I be fine as is, or do I need to take the pan back off and put blue Loctite on those threads?

Good news: I was able to put the oil pump in a vise (by the main body, not the neck) and really crank on that pickup to turn it more to get it to stay level. I also redid the thread sealant, so between those two things, it should be able to perform its best.

So I got everything buttoned up and installed and got it running. Bad news: I have a dead #1 cylinder. I have a ticking/tapping noise coming from there as verified by the mechanic's stethoscope, and a shake at low RPM that matches the tick/tap. The exhaust manifold is 80-100 degrees cooler than the other cylinders. I pulled that plug wire and had no difference in RPM, but when I pulled the wire from the #2 cylinder, I did get a drop in RPM. I checked that the rockers were on their pedestals torqued to 20 ft-lbs, checked that the pushrods were straight, and used a long screwdriver to verify that the lifters could turn in their bores. (I did forget to crank the engine while the valve cover was off to make sure the rocker arms get rocked. I might pull the cover again to do that.) I also took out the new spark plug and put in an old one to make sure the plug isn't defective, and no difference. I had verified with a spark test light that I'm getting spark there.

So I had a bit of an epiphany during church this morning. I bet that sunken exhaust valve seat is letting just enough tension off the spring that it doesn't hold enough seat pressure.  It would also explain the shake I was getting before I started this. I've also heard that a valve that's not seated hard enough can still show something on a compression tester since it doesn't measure leakdown. I'm going to try a .030 shim on the spring and see if it makes a difference. (I wanted to buy a few, but the only quantity O'Reilly would let me order to show up tomorrow is one.)

Got the lifter tick taken care of. The rocker arm for cylinder 1 didn't have a pool of oil on it like the others. I pulled the pushrod and a bunch of oil dripped out, so I think something clogged it, so my tick was from no oil through the pushrod. I could see through it, but I ran a pipe cleaner through it anyway and then sprayed brake cleaner through it. Put it back together and started it, and no more tick.

I think I've gotten just about everything. Changed the oil this morning to get the break-in stuff out of it. I leave for the trip on Saturday mid-day.

Engine did fine on the return trip too. 876.8 total miles driven in two days. No oil used that I can tell, although I haven't checked after climbing from Bakersfield to Tehachapi yet. I think we can consider this saga successfully ended.

Success stories are always great to hear. Glad it worked out for you; and I can add this to memory in case I have to pull it up for a something similar occasion!