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By most standards my ’35 should have been rebored, but it hsd NOS Bohnalite in very good shape, so I am gambling on original type pistons with a somewhat iffy original bore honed only but with the best oil control ring stack I could get. I could have had the thing bored and sleeved to keep the standard bore pistons, but sleeving isn’t without risk either, besides being expensive.

The main issue with a worn piston is the top groove is worn. In the past, instead of just automatically tossing old pistons and replacing, simple hand tools were available to cut the groove oversize and insert a steel “top groove spacer””. A piston will actually last longer with the top groove spacer than original (because the steel wears longer than aluminum). I think you can still get top groove spacers.

JIm”

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Yes, the steel strut is actually invar which is an expensive alloy that has the unusual quality of having zero expansion with temperature that keeps the aluminum the piston from growing in the bore when it gets hot – needed to allow the really tight piston clearance. It also was tin plated as an anti-seizure measure. they are more sophisticated than the lumps of aluminum you might get aftermarket.

Jim

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Okay that looks a lot better. Standard 1/8″ thick compression rings are .150 thick, so a .156 ring depth indicates the pistons were designed for standard ring wall. There just needs to be a small clearance between the inside surface of the ring and the piston groove so the ring floats in the groove as the piston cocks slightly in the bore. Your pistons look like they are in very good shape, presumably pretty fresh.

As I mentioned in my email, I have 16 unused 3.5″ standard bore plain compression rings that would fit if you want them. I also have 8 chrome taper face top rings if you want them. I bought them and didn’t use them in my Pierce.

I have been running chrome taper face top rings, Type 70 scrapers in #2 and #3, and chrome face 3 segment oil rings in my ’36 Packard for 20,000+ miles now. The antique piston ring suppliers often supply plain compressions and oil rings because they are easy, available, and have no issues with seating and quick break in. They have no issues with break-in because they wear easily and wear out quickly, so the rebuilder won’t come back at them with seating issues on fresh rebuilds.

Years ago Egge supplied all plain compressions for my Packard even though the original configuration was plain #1, type 70 scrapers in #2 and #3. 1930’s Pierce used the same. The rings they were supplying were stock for Allis Chalmers tractors that had a choice of plain or chrome.

I mentioned Grant because I wanted to go to an “inside bevel” chrome top ring on my Pierce and they had them long after the other suppliers ran out of stock. That is why I have left over chrome taper face. The other suppliers still have chrome taper face which is better than plain but not as good as inside bevel at oil control.

Type 70’s for the #2 groove and 3 segment oil rings should be easily found if desired.

Since the engine appears to not have many miles on it since rebuild I fully understand the desire to only replace what’s broken – my usual philosophy, but just to make life more complicated it looks like you have some alternatives if you want.

Jim

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I’ve broken a few rings myself. I won’t even put cast iron oil rings back in because they are so fragile when reinstalling and if one breaks there is no way of knowing until it is smoking like a steam engine. I’m not the most skilled mechanic!

Since you have them all out I would consider replacing them all and honing the cylinders, it wouldn’t be too expensive and can be done at home with a hone and hand drill. Honing should answer any seating issue as long as the taper isn’t too great. Cast iron rings with no effective air filter were only expected to last ~15,000 miles.

I would also consider advancing to the 1930’s and putting in a type 70 (Perfect Circle jargon)outside cut scraper ring in #2 groove and a 1950’s technology chrome rail expander ring for the oil. They won’t break on installation and will cut down the smoke at idle and riding compression. They reduce the pumping of oil past the rings on the inlet stroke under high vacuum. The rings stuck from deposits is mute testimony to the excess oil being pumped up.

I have to check the depth, but if the same I put these same dimension rings in my ’35.

I apologize for more free advice than wanted!

Jim

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Charles, are you just trying to replace the broken ring or are you replacing all? Your piston looks to be in very good shape.

Jim

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I found some difficult to locate rings from Grant. I have a number of piston ring catalogs, if you have the diameter, height and depth I might be able find interchange applications to help find workable rings. They look like basic 1/8″ thick plain compressions and a 3/16 oil ring. I won’t be able to get to it until the weekend.

Jim”

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Here are a few pics of mine showing the brake torque shaft going into the drivers side without bracketry, the U-bend of the shaft, and the bracket that is only on the passenger side of the rear axle.

Hope this helps.

Jim

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If the 836 is the same as 1935 845 I can take some pics this weekend.

Jim

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I would err on the side of looser. Automobile engines, particularly luxury car engines specified very tight clearances for basically one reason: to make them silent. Industrial/commercial engines specify much looser clearances to minimize friction, bearing temperature, and life. They make a lot of noise but ironically last longer.

As per my discussion on oil viscosity, tighter clearances also generate more friction and heat which is the enemy of babbitt bearings.

The following quote from J. F. Taylor’s seminal text “Internal Combustion Engine in Theory and Practice”:

“The usual recommendation for crankshaft bearing clearance is .001 times the journal diameter. The author’s experience, confirmed by most bearing experts, is this is a minimum value, and that values up to twice this amount are acceptable and often desirable. Small clearances are dangerous both because they do not allow enough for distortion and because they have less safety against wear and scoring by foreign particles…bearing coefficient of friction decreases as clearance/diameter increases.

The objections to large clearance include lowering of the value of the Sommerfield variable and hence a lower factor of safety against oil film breakdown. However, most bearings fail for reasons other than direct oil film failure. The present author cannot recall a bearing failure due directly to excessive clearance, whereas he has seen a great many bearing failures attributable to inadequate clearance….No journal bearing in any engine, no matter how small should have a minimum clearance less than .001 in.”

On my 845 the minimum recommended by Taylor matched the maximum (.0025) specified by Pierce. If you set clearances super tight it is extremely important as Greg mentions that the journals be round and have virtually no taper. Check the clearance in multiple positions to make sure there is no position where it has inadequate clearance. Plastiguage is useful in making sure that the journal and rod bearing aren’t tapered, and that the rod sits flat against the bearing The slightest bend or machining error of the rod bearing can make the rod ride one side and reduce its load capacity. A tight clearance has virtually no room for error. I wouldn’t trust any rebuilder to do a better job than Pierce-Arrow, and that means it is safer to err on the looser side of the clearance. It is also better from a heat and bearing survival standpoint.

I think many of the bearing failures on antiques attributable to bad babbitt may actually be from rebuilders proudly setting them up at the minimum clearance with the notion that is the measure of rebuild quality, and then putting in thick oil to give it that extra measure of protection.

Jim

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On further thought one should take the more obvious choice, if the nuts came loose without 40+ ft-lbs torque they were probably not torqued high enough. That would allow the caps to part slightly at high speed near top dead center with throttle closed at the beginning of the intake stroke and pound the babbitt at the parting line when they snapped back together.

Jim

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Always fun to theorize. Bill, for your rods if they are that consistent around the parting line I would suspect that when the babbitt was applied there was a slight contamination around the rod bolt holes, that spread to the nearby surfaces. Studebaker engineer Stanwood Sparrow noted that all it took to ruin a complete batch of babbitt was a single copper washer dropped in by mistake, i.e. pretty sensitive to contaminants.

I think he also noted that usually the babbitt did not fail near top dead center or bottom dead center where the loads tend to be the highest but typically about 45 degrees off where the loads would reverse from compression to tension (combinations of pressure loads and inertias throw then off from straight up and down).

Greg’s bearings look like they failed right at top dead center, which would imply the engine was lugged at high throttle low rpm with hot oil. That is the scenario of driving the car at highway speeds getting everything good and hot minimizing oil viscosity, then stopping and reaccelerating with a high throttle low rpm (lugging). Hot oil, high torque + low RPM is the most likely combination to break through the oil film at TDC. Its where multi-vis is an advantage.

Jim

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Paul, thanks for responding. Looks like I need to get some particle board.

Jim

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Sorry to keep bringing this up -maybe I’m obsessed- but I found (too late for me)wonderful pictures of the installation and arrangement of the 34-35 mufflers (perhaps also applies to ’33?). 21 years ago I squirreled away the 1995 model 4 issue of “The Arrow” that shows all three mufflers and the interconnecting pipes on a long wheelbase. It also shows the internal construction of the front and rear mufflers that of course agrees with the remains of the original muffler posted by Bill Lyons. These could be used to reconstruct new mufflers to the original design if someone has a mind to do that in future.

Unfortunately, when I was trying to figure out mufflers for mine I stopped short of pulling this issue out after I found a less detailed set of pictures in a different “the Arrow’ I had squirreled away.

One of the problems of delaying a restoration project for 20 years. Oh well!

Jim

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Greg, I actually have a mechanics stethoscope and tried to listen along the outside, but as you say I will need to take the lifter covers off and listen directly to each one. I am worried of course that it is the lifter that I had to make a new seat for. The fuel pump lever has me wondering a bit because the sheet metal lever arm just bears against the cam without a great looking bearing surface and I wasn’t sure at first that I wasn’t missing a part or that my insulator block is correct thickness. The stethoscope should tell the tale.

I am going to resist doing much more idle running and diagnosis until I get the steering, brakes, floor boards and orange crate in so I can drive it and get the initial break-in throttle slams done to start seating the rings.

Thanks!

Jim

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I should dig out the pics of a ’36 Club sedan I seriously considered buying in 1980 in North Carolina – wonder if it could be the same car?

Greg, the exhaust sounds great -very smooth and negligible pulsation, but there is a bit of a cheat since it had a long tailpipe extension several feet out the garage door. Without the blowby pipe and aircleaner assembly installed it blew lots of fumes into the garage – fortunately I have a big swamp cooler/heater system that can force outside air in then out so no one passed out.

At the moment I am wondering if the tapping could actually be the fuel pump lever. I installed a fuel pressure gauge at the carb inlet to adjust the electric pump regulator pressure. The mechanical pump bounces the gauge pressure dramatically every cam revolution so I am wondering if I have a big leak in one of the pumps check valves. I’ve never actually installed a fuel pressure gauge before, so maybe this is normal, but I would have expected a lot less oscillation with low fuel flow at idle.

Jim

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Ed, too late for me at this point, I have what I have and going to live with them, but maybe the next guy.

Thanks! Jim

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Ed, John Cislak obviously made a significant investment in reproducing mufflers years ago, but if he doesn’t intend to produce them again do you think he might consider publishing the specs from the originals?

Jim

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The mufflers on my 845 when I purchased it had obviously been replaced, necking down to a 2″ pipe replacing the #1 muffler and then using a 1 3/4

tailpipe instead of a 2″. My replacements are all 2 1/4″ diameter inlet/outlet and a 2″ dia tailpipe per the Pierce spec. Trying to snake that 2″ through the obstructions was a big challenge and I can see why the long forgotten muffler shop made life easier on themselves and used a smaller diameter.

I am in the process of reviewing old SAE engineering reports on vapor lock and in particular the effect of modern fuel properties including ethanol. Randy you are of course absolutely right, the last thing you want to do is insulate the outside of the fuel pump, it would make vapor lock worse by restricting air circulation. The thick insulating gasket is critical to reduce heat coming from the block. I think improving ambient air circulation around the pump and carb is the right direction.

My #2 is a heavy duty truck muffler much thicker than typical. If my ’35 survives initial start and driving the bare body/chassis around without a problem I will wrap them in muffler insulation for the next phase.

I would like to hear a Pierce with the original muffler design – I have been curious for 20+ years.

If I were as talented and dedicated as Jim Livings – who makes his own mufflers – I would replicate then myself, but too many skills to learn for a single car project!

Jim

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Bill, yes I think just a simple hex bead bolt (5/16 UNC if I remember right) locks the plate in place when not open.

I am hoping someone can confirm or deny that the pin is original equipment or if there was something better.

Jim

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Bill here is a shot of the timing cover and the pointed screw that goes through the back hole to attach. The pointer ends up a ways away from the timing mark on the flywheel but can be seen at the angle when looking back from the engine compartment. I assume it is original equipment and I guess close enough.

Not as easy as marks on the front damper but a lot easier than the E-type Jag where the pointer is on the bottom and I have to raise it on the lift running to adjust timing (is that really correct?)!

The timing cover plate is .093 thick steel.

I am struggling with mufflers and tailpipes on my ’35 today, hope to finally do the first start next weekend.

Jim

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