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Posted (edited)

Tomorrow I am going to pull the head then put in new rings. I've heard I need to pull one piston to determine the size rings required. If that is a fair statement, then which piston should I pull and measure? I know that I also need to mic the cylindar so will do that also.

Edited by pflaming
Deleted freeze plug question
Posted

Austin, could that mean several sets of rings? $$$$ Gonna pull all and measure before I buy a set.

Posted

most oversized pistons are stamped on the top withthe size. Is there a significant ridge on the top of the cylinder?? If so it should be removed first.

And yes folks fitted only one piston at a time if that was all that was needed. I remember back in the early 50's my uncle had a fellow come over and replace a piston and bore and hone a cylinder in his 40's Pontiac with the car in his driveway. they removed the hood, and the head, the oil pan, determined which cylinder/s needed attention and then with a deal that looked like a mini oil drilling rig that bolted to the block, after the cylinder was ridge reamed, and the piston removed. the rig enabled the operator to bore and hone the cylinder, then he cleaned up the mess, put in the new psiton and rings, buttoned everything bock up and went on his way. I think there was like 50 bucks exchanged for the deal.

Posted

Yes, I once had a 39 Plymouth motor I put in my 40 Plymouth sedan, it had .010, .020, .040 and .060, all in the same motor. Check it out before you commit to buying parts.

It used to be you could just buy a piston with rings on it, no requirement to buy a set. I suspect, although I don't recall doing it, that you could buy rings for one piston at a time.

In addition to boring a cylinder in your drive, there were also grinding services and machines to grind a crank in the motor and in the car. Anyone remember those? They'd come to you, at your home, in the dealer's shop or where ever.

Gene

Posted

Some things to consider about repairs to your engine.

The general rule of thumb is no more than .0025" "taper" or "out of round" on a cylinder. If you have more than that you should bore & hone the cylinder back to a modern day spec. I say modern day spec because the specs back then were probably not this tight. I have some old shop manuals that show some specs but back then very few shops went by it and even fewer actually had the equipment to measure it.

I recall those days when any motor that had 60,000 miles on it was in need of a rebuild. Today we have motors with 160,000 miles and still going strong. Mostly because we put a bunch more into a rebuild now and use better parts.

Doing any machine work with the engine partially assembled, like in the old days, is a bad idea. You'll never get it totally cleaned up.

A rebuild in the old days usually consisted of a good ridge ream, hone job, some new rings, gaskets and a fresh lapping of the valves. Not even close to what we do to a motor these days.

The ridge reamer is all dusty and don't get used much at all in our shop. If it has a ridge at the top of the cylinder it needs to be bored oversize, if it needs to be bored oversize it needs new pistons so we take the ridge out with the boring machine after it's been disassembled and run thru the hot tank.

I have customers ask me all the time "what would you do?" when it comes to rebuilding an engine. I think "do it all, do it right or why do it at all?" And then I think, I own an engine shop and don't have to pay somebody to do all the machine work, (so maybe my opinion don't really mean much).

With all that said I do think that a "back in the day" rebuild would be plenty good for most of these older engines. If you think about it how many will ever see even close to 60,000 miles again? But some people just like to do the best job possible and thats kinda the way I like it even if it is a little overkill.

Mike

Posted

Mike,

Yer specs for cylinder taper sorta' sound like you own a machine shop. I have successfully rebuilt older long stroke engines with .008 taper that are still running around here and are still happy. What you say is true for short stroke high rpm stuff, but our MoPar flatties are a little more forgiving than the tight spec you recommend, JMHO.

Otherwise, I completely agree with your logic about engine overhauls. Halfway measures usually last half way. Having said all that, I rebuilt my own 218 in the frame - cylinder taper around .005. Pistons were shot cause' the top ring land was hammered out, so new pistons and ringsl, and of course all new bearings. She runs beautifully, and will last a long time using modern oils available today.

Long stroke low rpm engines are much more forgiving on engine tolerances than the stuff on the road today. I would never even think of doing such an overhaul on an overhead cam aluminum block . . . etc.

Paul, sounds like you are well and truly into the engine now. I thought it was running and you were happy. What happened?

Posted (edited)

Greybeard: Followed your instructions and with a neighbor got it running but only with a 12 volt battery. The persisting problem was the compression not enough to start on six volts. We tried several things to raise the compression all without fail. At one time he taught automechanics and offered to help me do the rings to improve the compression. The oil pressure is good, the cylinders are clean, no ridge on the top and when I had it mic'd the cylinders were all alike. So I am going to ring it, get it running again and try to get in driveable. I am close for that but there is a lot of work left: windows, interior, and the other things will be done after I get it on the road. I realize this is not 'coutier' but . . .

Today I learned about the water distribution tube. This morning I removed the water pump and put a rod into the tube, it only went about 12 inches so I got a very stiff 42" X 1/8 inch rod, flattened the end like a screw driver end, put it on my drillmotor and slowly worked into the sludge, it was solid but it slowly yielded, what a mess, good thing I checked it out.

I built a puller, got a hole in the tube, and put pressure on it but it won't budge. It's under pressure now, maybe by Monday it will give???? On monday will get a puller and go at it again will also pull the core plugs and clean out the bottom.

As you know all this is new for me, so I am going a bit at a time. Lots of fun, quite enjoyable.

Edited by pflaming
Posted

Pat-what Dave and Mike both said is true-its amazing the amount of experience on this board. I know from a very recent experience that you can buy ring sets for individual pistons from NAPA. Just this past fall I bought a single set for the slant 6 in my pickup. My intent was to use them to measure the end gap in measured placed of each cylinder to determine whether I needed to go the whole nine yards on the motor job w machine work. The differences in the end gap combined with the ridge at the top made the decision for me. All 6 were bored over .030, block boiled, new cam bearings, rod and ring bearings, 3 angle valve job, new guides, springs-to the tune of about $1800. This engine runs better than it ever did, even though I've only put 400 miles in it (its a cruiser and show truck) that I've owned for 29 yrs. I've got my 52 1 ton apart for a miss on #6. Pulled it down, #6 exhaust valve and seat was shot as was the guide. The same machinist is going to replace the bad seat and guide in frame, then we're going to replace all 12 valves and freshen up the seats. Whoever went through this engine 15+ yrs ago did a .020 bore, new pistons, ring bearings, timing, gears, chain, water tube, and then set the valves too tight. This motor has no ridge, and still has crosshatch marks in the cyls, but I've only put about 3500 miles in the 15 yrs I've had it. So, after this novel-in answer to your question, yup you can still be individual ring sets.

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