Packard Forum Index » V-8 (1955-56)

In recent thread about "Finicky" Packard V8s, I mentioned a noise in the 56J's motor that sounded like a wrist pin, on the driver's side. It began after I swapped heads, cam, lifters, and several rockers.
Before swapping the heads, I had checked valve spring pressure on the replacement heads, and they were all weak. So I compensated a little by spacing them to around 1.700" seated length. OEM is 1.750" and, doing the math, there should still be plenty of clearance when the valves are opened.

The heads were rebuilt 8-10 years ago by an experienced machinist, now deceased. He sleeved the valve guides, installed hardened exhaust seats, and replaced valves as needed. He had mentioned the weak springs, but I told him not to worry about them since I am not a hot-rodder. His work was always second to none.

Following the wrist pin notion I removed driver side head and oil pan, replaced #1 piston & rod (not needed), and six rod bearings (badly needed). I also checked crank end play. In retrospect. I really found nothing that "put a finger on" the source of the noise.

Today, the noise is still there, exactly as before. It does not sound like a lifter, but having ruled out the bottom end, that only leaves the valve train. It could be: a loose valve seat; valve sticking in the guide; spring bind; rocker sticking on the shaft; push rod; lifter, or cam profile. Presence under light load would seem to indicate the problem is toward the combustion chamber, i.e. loose seat, or valve sticking in guide, but I am tired of guessing. IN hind sight, I wish I'd disassembled & inspected that head when I last took it off.

At this point I am frustrated and refuse to turn another bolt till I can accurately diagnose the problem. Current plan, run it till it blows. My AAA is paid up, and I have plenty of motor parts. In over half a million miles, I have never had to have a Studebaker towed, but might be headed toward the first time.

It is most pronounced under light throttle in 1st and 2nd gear. It may be present at higher RPM and load, but other noises drown it out.

Hi Joe:

If the noise cannot be isolated by cylinder and is running at half motor speed then it is likely valve train related.

Even the most obscure bottom end problems can be isolated without teardown, but it can take time and patience. It also helps if the technician uses hearing protection around the shop and avoids the trash coming out of the radio. In other words you need sensitive hearing.

Given the noise is load sensitive the valve train is probably not the origin. It may be as simple as an exhaust leak. If a cylinder is faulty a dynamic compression test may isolate the problem.

Hope this helps.

Wrist pin noise is usually at idle only.

However, it is a powerful v8. So try this:
Remove a spark plug wire. Test run the engine operating on 7 cylinders at a time until the noise stops. Then u have osolated then offending cylinder.

Possible transmission noise????

Tell us about the timing chain and gears. I had a similar noise but barely detectable from inside the car. Only 20k miles on the chain. However, when i placed a steth at the timing cover i could here it at idle.
Replaced chain woth an OEM CHAIN and noise stopped.

Thanks Tom & Packard V8 for the good food for thought.

A few problems with cylinder isolation by removing plug wires: It is silent at idle, and the tic only begins at around 2000 RPM under light throttle, in gear (car moving). Also, I have pacemaker, and the manufacturer specifically cautions against electrical interference, i.e. airport scanners, and I presume plug wires, especially if one accidentally "bites" me :)

In re-checking the math on spring clearance: they are factory set to 1.750" seated length. Coil bind is @1.250", so with .398" valve lift for intake and .388" for exhaust, that leaves .102" and .112" before coil bind. My setting them to around 1.700" left .052" and .062" before coil bind. Modern cam manufacturers recommend a minimum of .060", so re-doing the math may just have revealed the problem.

I am on my way out to the garage, to remove a .030" shim from each spring on that head. Will post results later.

Thanks Again,
Joe

Check the valve seals!!!!!!

Note thatmy recommendation to remove plug wire one ata time is to remove it while engone is OFF. Then test drive engine while plug wire is removed.
I doubt that procedure would cause any medical problemss??? No???!

The v8's have a lot of power making such.a.doagnostic viable.

Well that did not fix it even a little. I did discover it will make the noise sitting still, at 3000-3500 RPM.

Packard V8 I misunderstood. I agree, that's a good way to isolate the cylinders. But for now, I am going back to the earlier plan, drive it till something breaks, then we will know what the problem was. Meanwhile, I will go ahead and assemble a fresh shorty block in the next few months.

Forgot to mention, new timing chain when I swapped the heads (OEM type), but re-used the gears, since they looked OK.

I still say the Packard V8 can be finicky sometimes :)

Thanks Again Folks