compression test readings on standard 8 from 733

[34PackardRoadsta]

Dear All,

I did a compression test before pulling the head. The test was done on a cold engine, all plugs removed, cranked through 4 compression cycles. I got the following readings (cylinder 1 is closest to front):

Cylinder Reading (PSI)

1 60

2 62

3 52

4 60

5 62

6 64

7 60

8 64

Are these appropriate for a 1930 engine? Also, is the 10 psi lower value in cylinder 3 indicative of a large problem?

Thanks for the help.

Tom

[34PackardRoadsta]

OK, following the procedure outlined in my Dykes, I added a quarter cup or so of 30 weight oil and retested compression. The procedure was:

1) Add 1/4 cup of oil to cylinder through spark plug hole. Wait 2-3 minutes.

2) Attach compression tester.

3) turn over engine through 4 compression cycles.

4) record measurement

5) Repeat 1-4 on all remaining cylinders.

For good measure, I did this twice.

My measurements are now (Cylinder - PSI)

1 - 95

2 - 100

3 - 100

4 - 92

5 - 94

6 - 96

7 - 100

8 - 100

So, am I correct in thinking I have a potential ring problem in cylinder #3 and a potential valve problem in cylinder #4 , and perhaps cylinders 1 and 5?

Thanks,

Tom

[Rusty_OToole]

Your rings aren't seating.

On another board a member solved the same problem on an old 6 cyl Chev by putting a little Bon Ami cleanser down the carb with the engine running.

Not suggesting you do the same thing.

[Owen_Dyneto]

My conclusion would be that your rings are badly worn, cylinder walls also a possibility. With the engine apart valve and guide condition should be evaluated though I don't see evidence from your data that it's needed. Valve grinds on this type of motor were generally an every 25-40,000 mile requirement.

[34PackardRoadsta]

Thanks folks. The engine has around 50K miles on it. What is the likelihood I need to do a complete rebuild on what I would consider a low mile engine? I know I can tell more once I have things apart, but I guess I want to be mentally prepared for a rebuild!

As for easy...

I was hoping to get away with decarboning and then grinding the valves. I know, not likely!

Thanks,

Tom

[Clipper47]

Tom, How long has the car been sitting and how often has it been used? I found that with my Packard which had only been driven about 1000 miles in 50 years a few hundred miles of driving really made a big difference in oil burning and performance once the rings had a chance to seat. Also how much do you plan on driving the car.? To me it doesn't make much sense to overhaul an engine to drive a 1000 miles or less per year if it is still running OK otherwise. A little oil burning is no big deal and hardly worth the expense of an overhaul in a collector car being driven to local shows etc. Just my 2 cents.

[Guest imported_Speedster]

Hey, I Don't call 92 to 100 psi bad compression. It's not great, but I sure wouldn't overhaul it because of those readings. A maximum difference of 8 psi is good.

You may want to try another gauge to get a second opinion.

I've found that some gauges read much higher or lower than others. It also matters if it's the thread-in or push-in type gauge.

I have a favorite guage, a push-in type. It's my favorite because it always reads about 20.psi Higher than my others. LOL

[Owen_Dyneto]

Your true compression readings are the ones before you added the oil, the ones in the 50-60 range. I don't recall the compression ratio of that engine, but probably it should be somewhere in the range of 85-95.

For engines of that era, 50,000 miles would have been considered high mileage with a motor rebuild coming due soon, but of course that depends very much on what the motor's experiences have been.

[Restorer32]

Your engine needs a rebuild.

[34PackardRoadsta]

Thank you all for the replies. Consensus appears to be a rebuild. I guess it is going to be awhile before this sedan hits the road again! Just be ready for more questions, as I have never done a rebuild on anything with more than one cylinder! So, to start, here are the first questions :

1) Reference Materials: I have a Dykes from 1933, a Chilton's from 1940, the red Packard Service book, parts list, and a collection of posts from this site and packardinfo from folks that have done rebuilds on the standard eight of this era. What other reference material should I be looking for as I dig into this rebuild?

2) Tools: What specialty tools should I be looking for. I have the standard stuff.

3) Can I do the rebuild with the engine in the car (drop the pan, pull the head and if necessary the cylinder block)? Or would it really be best to pull the whole thing?

Thanks,

Tom

[34PackardRoadsta]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Speedster</div><div class="ubbcode-body"> Hey, I Don't call 92 to 100 psi bad compression. It's not great, but I sure wouldn't overhaul it because of those readings. A maximum difference of 8 psi is good.

You may want to try another gauge to get a second opinion.

I've found that some gauges read much higher or lower than others. It also matters if it's the thread-in or push-in type gauge.

I have a favorite guage, a push-in type. It's my favorite because it always reads about 20.psi Higher than my others. LOL

</div></div>

Rick,

BTW, I'm not ignoring your advice here. The consensus, and my gut, says it is time to rebuild. The car sat for a few decades, and I have no idea what was done when it was started again. I have a feeling not much, so extra wear during the first few starts after sitting probably occurred.

I have two compression gauges, both screw in, and both give similar readings. Both were used during the test to speed things up. As one was being removed, my buddy could put the other one in.

Tom

[Guest imported_Speedster]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Owen_Dyneto</div><div class="ubbcode-body">Your true compression readings are the ones before you added the oil, the ones in the 50-60 range.

</div></div>

How do you figure that? I think he did those readings with the cylinders completely dry (no oil). When the engine is running the cylinder walls are covered with oil, so the test needs to be done with the cylinders oiled, correct?

I still say the engine has Good compression.

[Tom M]

Tom,

I was in the same position as you. First I sent the block and rods out. I had some friends come over one day and they looked over my crank and said it needed to be cleaned up. So then I pulled the lower half and sent it out. I personally think if you’re going to go that far with it I would pull it all the way out.

If you need place of reference to help with your rebuild let me know.

[Guest imported_Speedster]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 34PackardRoadsta</div><div class="ubbcode-body">Rick,

I'm not ignoring your advice here. The consensus, and my gut, says it is time to rebuild. </div></div>

Okay, it's your car, money and time. And having Fun with your car, money and time, Is What it's All about.

[Guest imported_Speedster]

It's best to pull the engine when working on bottom end.

I found that since there's no regular engine stand that will work with these long engines, when removing and installing the postons and rods it's best to rotate engine vertical, on it's tail end (tranny mount end). That way one person can do it without fighting gravity. The crankshaft can be removed and installed with it in that vertical position, but the crank is not easy, for one person to do, no matter how it's done.

I rotated vertical by lifting with an A-frame hoist then lowered to a pallet, with 2x6 wood blocks and with wheels attached, so I could move it around. 4" wheels work great.

With it vertical you can work all the way around the engine, with no engine-stand blocking access to part of it.

[34PackardRoadsta]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Speedster</div><div class="ubbcode-body"> it's best to rotate engine vertical, on it's tail end (tranny mount end). </div></div>

I'm not sure what you mean by "rotate engine vertical". Just to be sure, you are suggesting that I stand the engine in a vertical position once I pull it? Or are you talking about some sort of rotating engine stand (not a regular stand) that you made?

I'm really looking forward to dealing with these giant parts .

Tom

[Owen_Dyneto]

Speedster, with a running engine, no oil should be present above the piston, it gets onto the cylinder walls when the piston is TDC thru the squirt hole in the rod big end when it aligns with the opening in the crank, and perhaps a bit from splash and run-off fromt he wrist pin. The lowest piston ring is the oil control ring and removes the oil from the wall on the downstroke, thus compression readings should be done first without adding oil thru the top and that reflects the true compression. Adding oil from the top is often down to determine if low compression such as this engine has is due to rings, or valves. If the compression doesn't increase after the oil, the problem is valves, if it does increase, then the compression loss is past the rings because the oil added above the piston is acting as a temporary sealant.

[34PackardRoadsta]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Owen_Dyneto</div><div class="ubbcode-body">...if it does increase, then the compression loss is past the rings because the oil added above the piston is acting as a temporary sealant. </div></div>

This is what I see. When I test a cylinder after it has gone through more than a few compression strokes, the resulting readings begin to drop. Thus the oil is leaking past the rings and is no longer acting as a sealant.

I think maybe I will just add some high temp gasket sealer to the cylinders and forget this whole rebuild thing. Ha, got ya! Really, just kidding ; though someone, somewhere, has probably done something similar .

[Guest imported_Speedster]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 34PackardRoadsta</div><div class="ubbcode-body">

I'm not sure what you mean by "rotate engine vertical". Just to be sure, you are suggesting that I stand the engine in a vertical position once I pull it? </div></div>

Yes, set the engine on a wheeled-Dolly, on it's flywheel end, with the balancer end on top. Much easier to work on that way, if you are doing it with no help. If 2 people will be doing it then that's probably not necessary.

I've always had to devise ways of doing things by myself.

The same dolly can be used when the engine is in horizontal position with more 2x6 framing to keep engine from rolling over.

[Owen_Dyneto]

To address the question about whether the engine rebuild can be accomplished "in the car", my position is that it depends very heavily on the condition of the crankshaft. If the journals are dead round within 0.001", bright and shiney with no surface defects at all, you might be able to do a credible rebuild. You can remove the bore casting and have it bored or sleeved and honed, and you can remove the cam to replace the cam bearings with the lower block still in the car. But if the crankshaft if even slightly out of spec, you'll be doing it all over in not that many miles, and this time pulling the engine.

[Guest imported_Speedster]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Owen_Dyneto</div><div class="ubbcode-body">, with a running engine, no oil should be present above the piston, </div></div>

I've found that compression goes up greatly if the engine has been run for a few seconds before taking the compression reading, that must be due to oil on the cylinder walls?

Only running it for about 10 seconds is enough time for cylinder and rings to get oiled but not long enough for it to get Too hot to touch.

I realize that most of the oil film, above rings, is burnt away during the combustion stroke, but it's redeposited during the other strokes, so it's there during the compression stroke.

I know because I've had engines that burned a Lot of oil.

[34PackardRoadsta]

Running the engine will also expand the pistons, correct? I would think even 10 seconds of running would heat the pistons enough to expand them. Wouldn't this contribute to the higher readings as well?

And cranking the engine for about 10 seconds with the choke pulled (but key and fuel off) would also oil the cylinder walls, right? In my case this does not increase compression.

Tom

[Guest imported_Speedster]

I don't think 10 seconds run time would change expansion that much, but that's possible.

No, just cranking the engine would not be the same thing, since oil pressure would not be as high, thru oil injector holes, and the crankshaft would not be throwing oil up into cylinder like it does when running.

[Guest imported_Speedster]

That's what the term 'Burning a lot of oil' means.

It means that an excess amout of oil (more than Normal) is getting past the rings.

[Clipper47]

Didn't cars of this vintage burn oil as a matter of course which would not be acceptable in a modern car. I seem to recall that one quart in 600 miles was considered normal in the 20's and early 30's. If the car has been sitting for decades I would drive it for a few hundred miles and do the compression check again. I wouldn't be surprised if it just needs a few miles to loosen the rings and sort itself out. Doing a rebuild without driving it for a while seems a bit extreme from an expense point, in my view, depending on what you plan to do with the car but if you are adventurous and looking for something to do and have the $$$ then go for it!

[Guest imported_Speedster]

Absolutly, I Agree completely.

[34PackardRoadsta]

Dave K, Rick,

The only problem with driving it is that I currently have very low power, so something is going on. That is why I started to pull the head, so I could check valves and de-carbon things (a boroscope check shows a LOT of carbon in some of the cylinders).

I had already done the usual stuff for power: replace plugs, condensor, coil, plug wires; clean and rebuild carb; clean fuel system and use good fuel; etc. Still had a very difficult time getting up hills, even in second.

The car did not burn a particularly significant amount of oil, at least for a car of that era.

Once I get the head and pan dropped, I will be able to tell more. I just need to get my brother over hear to help .

Tom

[Guest imported_Speedster]

The first thing I would suspect is the Carb not adjusted properly. Are you using the type carb that has large air-valve on top, adjusted with nuts above 2 vertical coil springs, under banana-cover?

If so, it may not be adjusted to let in enough air in when engine is in high vacuum.

The next thing I would check for is a vacuum leak at intake-manifold, carb, gaskets or lines to vacuum-fueltank, etc.

Is this the type Carb you are using or is it one of those 'Modern' things?

[34PackardRoadsta]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Speedster</div><div class="ubbcode-body"> The first thing I would suspect is the Carb not adjusted properly. Are you using the type carb that has large air-valve on top, adjusted with nuts above 2 vertical coil springs, under banana-cover?

If so, it may not be adjusted to get enough air in when engine is in high vacuum.

The next thing I would check for is a vacuum leak at intake-manifold, carb, gaskets or lines to vacuum-fueltank, etc. </div></div>

The carb is the Detroit Lubricator 51. The only adjustment for fuel flow comes from the metering pin screw on the bottom of the carb (see photo). After the rebuild (and adjustment of the float valve) I adjusted this according to the manual.

When I first got the car, it was missing badly, and smoking like crazy. The carb was completely gummed up, the fuel tank was filthy, and the vacuum tank was filthy. The points were burned, the condensor was bad, the plugs were ancient, the plug wires were cracking, and the coil was in poor condition. Oh, the cooling system needed flushing, and the water pump was leaking like a sieve.

With all this fixed, it ran very smoothly until I tried going up a hill. Then it would just not have enough oomph (still ran smoothly).

If there is something else that I have overlooked that will save me from tearing my engine down, I would love to hear it. I am still quite new at working on these new-fangled multi-cylinder gasoline engines .

Again, thank you for your help. I really really do appreciate the time everyone has taken to answer my seemingly endless questions.

Tom

p.s. Rick, it looks like we co-posted! Lovely carb (should be on a mantle!), but definitely the older model.

[Guest imported_Speedster]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 34PackardRoadsta</div><div class="ubbcode-body">

The carb is the Detroit Lubricator 51. </div></div>

Uh-oh, One of those 'Modern' Carbs.

Well, I can't help much with those 'New-fangled-contraptions' that are Not Shinny enough.

But, don't forget a '30 Standard-8 engine didn't have a lot of horses, even when it was new.

I guess you could hide a turbocharger under the floor-board?

[Rusty_OToole]

50000 was a lot of miles in the 30s. Most cars were ready for an overhaul at 20,000 or 30,000.

A ring and valve job would be done with the engine in the car. Take out pistons, deglaze cylinders, replace rings, grind in valves with grinding compound and a sucker stick.

Tighten up the bearings by removing shims as necessary.

But that was a long time ago when your car was a young used car.

In view of the car's age and condition it will most likely need the engine taken out and completely rebuilt.

You can take off the head and check for bore wear and valve wear. With luck you might get away with rings and valves. But if the cylinders are tapered more than .007 it is recommended you have them trued up and new pistons fitted.

[34PackardRoadsta]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Speedster</div><div class="ubbcode-body">

But, don't forget a '30 Standard-8 engine didn't have a lot of horses, even when it was new.

I guess you could hide a turbocharger under the floor-board? </div></div>

I understand that I'm not going to go racing up hills with a 90hp engine. At the same time, I should not have to drop into 2nd (or middle, or 3rd, or whatever you call the gear below top on these weird 4 speed transmissions) and then struggle to get up a moderate grade. I'm pretty sure a tubrocharger would do little for this engine in it's current state .

[Owen_Dyneto]

I've driven my Packard standard eight with the 320 engine over 45,000 miles; modest horsepower not withstanding, the long stroke provides very abundant torque, I've almost never met an upgrade I had to downshift on.

Rusty is correct about typical engine life between rebuilds; I've made that point before, the day of 100,000 miles before rebuilds or at least between valve jobs and re-ringing didn't come until some years after WW II.

[Rusty_OToole]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Owen_Dyneto</div><div class="ubbcode-body">I've driven my Packard standard eight with the 320 engine over 45,000 miles; modest horsepower not withstanding, the long stroke provides very abundant torque, I've almost never met an upgrade I had to downshift on.

Rusty is correct about typical engine life between rebuilds; I've made that point before, the day of 100,000 miles before rebuilds or at least between valve jobs and re-ringing didn't come until some years after WW II. </div></div>

The 20,000 to 30,000 miles between overhauls comes from some late 30s Motor magazines. The American garage and dealer magazine not the English one.

They were referring to the typical car of the day. I have also seen a quote from a Pierce Arrow expert claiming a 500,000 mile engine life for a Pierce dual valve six or straight eight. Presumably with periodic overhauls.

Don't know what one would expect of a Packard, Cadillac or other luxury car. Perhaps 50,000 between overhauls would be more like it for a quality car?

Experiences from owners of 30s luxury cars would be of interest here.

[Restorer32]

The likely scenerio goes something like this; You could remove the head, pull the pistons ( remember that the rods will not come out thru the top of the engine), deglaze the cylinder walls, install new rings and reassemble everything. Now, laboring under increased compression the bearings will likely give out and you will need to pull the engine anyways. My advice, do a complete rebuild including bearings, pistons and rings, valves, guides and springs, etc. Don't forget to plane the head and deck the block to insure against those pesky head gasket leaks. Also have the block and head magnafluxed to find any cracks. A bit expensive, yes, but the car is worth it. Alternatively, drive the car as is, recognizing its limitations due to advanced age. At 50,000 miles that engine has about reached its life expectancy. Be gentle.

[mrpushbutton]

If you determine that you are going to pull the engine and rebuild it, make sure you send the bore casting and head out for chem-stripping to insure that the cooling passenges are clean and can adequately transfer heat. There is a fellow over on the Chrysler forums right now that has a recently rebuilt '29 Chrysler engine and his rebuilder made some bitches-brew from muratic acid and water and he's having trouble because of rust still coming loose in the cooling passenges. This wouldn't happen with the chem-strip process, and you are insured to have a cool runnning engine afterwords, providing your radiator is clean and in good shape.

[Rusty_OToole]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Owen_Dyneto</div><div class="ubbcode-body">I've driven my Packard standard eight with the 320 engine over 45,000 miles; modest horsepower not withstanding, the long stroke provides very abundant torque, I've almost never met an upgrade I had to downshift on.

Rusty is correct about typical engine life between rebuilds; I've made that point before, the day of 100,000 miles before rebuilds or at least between valve jobs and re-ringing didn't come until some years after WW II. </div></div>

Reminds me of something Packard said. That the 1954 and older straight eights had a life of 18,000 miles in high speed tests while the 1955 OHV V8 had a life of over 100,000 miles.

This was from a press release at the introduction of the new V8 engine.

Mind you, Packard had the best high speed test track in the industry. It is possible the straight eight would wear out that fast at constant speeds of 90 - 100 MPH. But have a much longer life at more reasonable speeds.

[Guest imported_Speedster]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 34PackardRoadsta</div><div class="ubbcode-body">I understand that I'm not going to go racing up hills with a 90hp engine. At the same time, I should not have to drop into 2nd </div></div>

I don't know how steep the hills are you are driving on but I do know there are some Very Steep hills around Austin, that would most definitely require 2nd gear.

No Turbo huh, I really wanted to See that!

I'm not still trying to talk you out of doing a complete overhaul, since you seem determined to do it, I'm just trying to make sure you consider all posibilities before doing it, because it is a Major project.

BTW- I call them Low, 2nd, High and Low-low or Stump-puller.

[Tom M]

Tom,

What side was the T slot facing when you pulled the piston?

[34PackardRoadsta]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Restorer32</div><div class="ubbcode-body">The likely scenerio goes something like this; You could remove the head, pull the pistons ( remember that the rods will not come out thru the top of the engine), deglaze the cylinder walls, install new rings and reassemble everything. Now, laboring under increased compression the bearings will likely give out and you will need to pull the engine anyways. </div></div>

I think this has been happening all along. Clean the fuel system, the problems with the ignition become apparent, get the ignition nice, problems with the carb become apparent, etc.

Anybody know a good shop in austin to help out with the cylinder head and block (mangaflux, planing, etc.)?

Thanks,

Tom