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Unexpected piston condition in 1940 248


Daves1940Buick56S
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As I mentioned in another thread, I pulled the cylinder head a couple of days ago to facilitate valve spring replacement and further block coolant jacket cleaning. I was a little surprised to see what appears to be a fair amount of oil on a few of the cylinders. I replaced the rings 2 years ago and don't think I have put more than 200 miles on the engine since then. No evidence of oil burning, i.e. no smoke and oil level in stick has not dropped.

 

Don M suggested that I may have put some of the rings on backwards, although I remember being pretty careful and I am pretty sure ring #2 had the word "top" on it so it would go on the right way (I used Hastings rings). Since I already have the head and other stuff pulled off it won't be a huge effort to pull the pan and pull out one of the worst examples and see what I did.

 

So here are photos of each plug and piston top:

 

post-129380-0-90369000-1456270362_thumb.post-129380-0-04140800-1456270340_thumb.

This is #1, looks OK, all dry, some light carbon

 

 

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#2, a little oil but plug looks good

 

 

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#3, one of the bad ones, fair amount of oil on piston and plug, including center insulator

 

 

post-129380-0-46207500-1456270606_thumb.post-129380-0-60290200-1456270617_thumb.

#4, some oil on piston top but plug looks pretty good

 

 

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#5, piston not too bad but plug is worse than #3

 

 

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#6, a little oil present but overall pretty good

 

 

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#7, some oil present but plug center looks good

 

 

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#8, like #2

 

 

Any ideas?

 

Thanks, Dave

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Even soft rings made of cast iron, cannot seat in 200miles.

 

Worse yet, 200 miles in 2 years might mean the car gets started but never really brought up to proper temps for long periods.  That will affect plug color, because it never gets run enough.  Long ago, it was said that 80% of engine wear is during warm ups.

 

If you used chrome rings, it may never seat in, due to no miles driven.

 

cast iron is always best on a car that will never see a lot of mileage totals.  Chrome is for a very extended life, way beyond what most collectors cars will see.

 

 

 I'd maybe choose to finish the head work, and then run that car on a 200 mile trip, to see how the plugs look.

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Dave,

I agree with Mark, in that those plugs look awful rich.

Have you leaned her down at the carb, for a good idle, and set the timing just a bit forward of the "book" ?

Are they A.C. 46's ?

For no more than you drive her, I would install about 2 ranges hotter plugs.

 

Mike in Colorado

Edited by FLYER15015 (see edit history)
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F&J: Yes, these are Hastings cast iron rings, not chrome.

Mike: Timing was at 9 degrees, I backed off to 4 degrees after I started getting pinging but pinging still occurs, maybe it's the carbon buildup causing it. I have AC45 plugs since they are what I can get, I will renew the search for 46's.

Dave: Interesting idea, will check now that the head is off, my machine shop guy said the guides were good when he serviced the head.

Larry, Brian: OK, I had been led to believe rings would seat in abt 100 miles, perhaps that is on newer cars.

 

Thanks for the great advice, I knew I could count on you guys!

 

OK, since I have it this far, I will pull the pan (now that I know the tricks to doing this it's a lot easier) and get the oil pump overhauled, something I was thinking abt doing anyway. I will pull piston #5 since it is abt the worst, and if the rings are on properly, I will put the piston back in and then button up after the head work is complete and try to run the cr@p out of it this summer.

 

Cheers, Dave

Edited by Daves1940Buick56S (see edit history)
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Ring break-in on unbored engine:  I think you need 500-1,000 miles with some fairly hard driving, such as pulling up a grade at more than half throttle, or if you're in the flatland, accelerate from 25 to 55 fast and hard.  Then coast down to 25 and do it again.  Do this 20 or more times minimum.

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George: Yes, I have heard about that method, and I have tried to do the accel thing a few times, will do more after it's back together.

Mike: Good idea, I ordered some NOS 46's off flea bay last night, the 47's available there are all "S" prefix which sticks the electrode further into the chamber. Didn't see too many 48's.

 

So I got the oil pan off today, came off easy now that I know the tricks. I pulled the oil pump and am sending it off tomorrow for a rebuild at EGGE.

 

Then we pulled piston #5. First glance, all ok. So I looked at the rings, still clocked just like I set them before install. I checked the second ring and the dot is indeed at the top. I went back to the Hastings master catalog and for set 428 it specifies the ring types, from the top, as 032, 126, 860/732, and 501. The top ring, 032, installs either way. The second ring, 126, has a bevel on the bottom inside and has a dot to indicate top orientation. It is installed correctly.

 

Now, according to the catalog, ring 3 is supposed to be the the 3 piece flex-vent oil control ring and ring 4 is the one piece oil channel ring. I am pretty sure the ring installation packages indicated the flex-vent ring was to go into the 4th slot and that is what I did. When I took the engine apart the first time 2 years ago, the pistons did not have the flexible ring at all but rather the one piece channel rings in both the 3 and 4 slots.

 

So now I am a bit confused, I thought the flexible ring was supposed to go in the bottom slot. I am going to call Hastings tomorrow and see what they say. Dunno if this would make any major difference though, would it? Hope not as I am not really keen to pull all of the pistons and swap the last 2 rings.

 

Cheers, Dave

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Dave,
Does your oil pump bottom plate look like this ?
Each grey area around the perimeter is a leak. 
I polished mine down with 80 grit emory cloth on a flat steel plate till these were gone, and put a THIN coat of #2 Permatex round the edge.

100 1224

 

Raised the oil pressure quite a bit.
 
Mike in Colorado
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Mike: 

 

Yeah I followed your advice and did that 2 years ago. It did help some, as well as tightening the conn rod bearings, and tightening the mains last year. Incremental differences all in the right direction, but my guy in Berryville looked at it last summer and said the pump was somewhat worn, so hopefully this will get things to where I can live with it, although I don't think I will get to the 45 lb spec when hot, the only thing left would be cam bearings but I'm not going there. Next owner.

 

Cheers, Dave

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If the pump cover is pot metal, resist the urge to shim the spring to increase the oil pressure. That will put additional stress on an already marginal part, causing additional flexing. The stock 45psi, running is just fine.

Some pumps have a steel cover and aren't as likely to deflect.

 

The folks at Hastings are really helpful. I spoke with a really knowledgable woman there - Dawn Hill (x 1359)  at Hastings

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If you can't find the AC46, AC47, or AC48 spark plugs you are looking for locally, Green Spark plugs for England will have them.

 

I have bought several items from them for my Triumph TR4 and found they have the largest selection of spark plugs I have found.

 

Click on the spark plug pictures and it will take you to the detailed specification for each plug by then clicking on "Additional Info", or select "See Alternative" for other brands of plugs with the same specifications.

 

The shipping is reasonable, when you consider they are shipping from England.   

 

At the current exchange rate, multiply the plug cost listed in pounds by 1.41

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Thanks Don! I just got off the phone with Dawn and - I am ok.  If all 4 slots are above the piston pin, it doesn't matter that the flex-vent is in the bottom slot. So I am going to put #5 back in and press on with the other work. BTW, I was lucky to even get 30 lbs at speed with hot oil, much less 45. I frankly don't expect 45 at speed even after the pump rebuild, but at or a little above 30 would be fine with me.

 

Vila: Thanks, I will take a look. I also have a Triumph, a TR-3 small mouth.

 

Billy: Love it, I feel your pain!

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We used to have a counter guy at our NAPA store that we called Two Trips. Take a guess how he got that name.

 

Back to that 56S; only 200 miles, that's hardly time enough to get warm enough to open the choke. Get that car out and run it. That light driving will just aggravate little mysterious stuff. You meed to shoot for 1,000 miles a year and break things. It makes it more obvious to fix.

 

I get 1,000 miles or more on my '60 per year. Last year I made a commitment to put 1,000 miles on the Park Ave convert. I bought it in Spring 2011, rebuilt everything mechanical and wasn't happy. Last year I swore I'd break it to find the problem. Funny thing, a guy stood next to it in a parking lot and called the problem as casual as ordering a burger. I ended up putting 1200 happy miles on it last year.

This year I plan to give the '48 Packard a thousand mile shakedown. I bought it two years ago and have only put, maybe, 50 miles on it.

 

When you have more cars than a sane person it really takes work to rack up some miles. But when you do all those mysteries and quirks just go away. It is hard to do. Just about anywhere you go the average speed from pulling out of the garage to putting it back in averages something like 35 MPH. That means you have to find 30 hours per car for driving. It's not as easy as it sounds. But if you don't the weird stuff starts complicating matters.

 

Get them out and drive them. It is the best way to maintain their reliability and maintain their highest value.

Bernie

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Don: Dawn pretty much said the same thing as everybody else - there is no problem, drive it! And that I am ok on the ring order, which was the reason I called her. And, like I said above, cam bearings I am leaving to the next owner!

 

Bernie: Wise words from you like always. You know, a lot of times I keep on thinking that my Buick should at least run as well as my old '66 Fairlane, which was a basic auto just like the Buick with no bells or whistles. But, like you pointed out, I keep forgetting that I put more than 25k miles a year on that Ford for several years from '71 to about '77 or so. So I really need to get the engine buttoned back up, which I will do once my valve springs and rebuilt oil pump come back in, and go run the heck out of it. I do need to get the rear sorted, if the 3.6 I just got doesn't work out I will have my old 4.44 put back in so I can at least drive it.

 

Cheers, Dave

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We just try to drive our car every chance we get. Any time the trip will be at least ten miles each way, less than that I feel is not so good for the car. When the temps start hitting 90 degrees and up to 115 here in Vegas we won't drive it as much. Its just not fun driving a car without AC in those temps and if it gets caught sitting in traffic without moving I am afraid of it getting to hot. I think its not good for a car to sit and anyways its just more fun to drive them.

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