Sealed Power piston?

[Local2ED]

In the course of taking apart my 230cu.in. flathead in my 1958 Dodge Coronet I dropped a piston out of my hand and broke the top of the piston. I ordered a new Sealed Power #37P piston. When it arrived I noticed it did not have the verticle slot that has a hole at the termination point on the sides of the piston. Also there were less holes in the third down ring groove (8 holes on the original spaced out about 2/3 of the way around the piston VS 4 holes on the replacement, two each on opposite sides of the piston.) Everything else looked OK. What do you think about using this piston?

Thank you.

[Plymouthy Adams]

so in taking your engine apart I assume by reading that he stock bore is good and you will just re-ring the unit..but most improtant..what is the weight of this piston and can it be wieght match ground to that of the others...unless you have the entire set I would not be inclined to mismatch pistons..

[ptwothree]

In the course of taking apart my 230cu.in. flathead in my 1958 Dodge Coronet I dropped a piston out of my hand and broke the top of the piston. I ordered a new Sealed Power #37P piston. When it arrived I noticed it did not have the verticle slot that has a hole at the termination point on the sides of the piston. Also there were less holes in the third down ring groove (8 holes on the original spaced out about 2/3 of the way around the piston VS 4 holes on the replacement, two each on opposite sides of the piston.) Everything else looked OK. What do you think about using this piston?

Thank you.

When I pulled my 218 down, I found a 37P in the #5 hole. The engine ran and idled fine. I ended up replacing the other 5 with more 37P's cause the ring lands were worn out.

I ended up with a new 37P in the box if you or anyone else needs one...cheep+shipping.

[46busboys]

Use it, it won't hurt a thing!!!

[DJ194950]

About 10 years ago i was working on a 6 cyl. john deere diesel motor in a power sweeper (8' bloom for roads) that had that a radiator leak and was greatly overheated and scored one piston and cyl.

Torn down to short block and sent to a very experienced(old) machine shop for repair.

When the call came to pick up the repaired motor i noticed that only 1 cyl. had been bored and a new piston installed.

When i inquired with the macineist about this he said that redoing only 1 cyl. would be fine for a long time as this motor only ran 2,000 -2,500 rpms and therefore the balance of the new piston(larger) would not have any real effect on this motors life as it wasn't new anyway heavy counterweights and all for a long stroke diesel.

Our motors have some simialities to a diesel, long stroke,heavily counterbalanced and low rpms.

WHILE before everyone gets overheated!! I did not really appreciate the overall idea!!

BUT, the very small differance between (stock??) and replacement piston weights should not be noticeable! Is the motor new??

Just my 2 cts.

Also do not by a used sweeper from a rental co. that goes by the initials URI:eek:

Happy Mopar Motoring

Doug

[Local2ED]

so in taking your engine apart I assume by reading that he stock bore is good and you will just re-ring the unit..but most improtant..what is the weight of this piston and can it be wieght match ground to that of the others...unless you have the entire set I would not be inclined to mismatch pistons..

The bore is good, standard size rings will work.

My concern is the missing slots on the sides and the fewer holes in the third ring land.

Are the holes for oiling purposes?

What do the verticle slots do?

Thanks.

[Niel Hoback]

The holes are to drain oil that is wiped off the walls by the oil ring. The slot is an expansion slot to allow the piston to change shape and fit the cylinder better while helping reduce piston slap.

[Rusty O'Toole]

Different pistons made by different companies have slightly different designs. All should function just as well. The T slot you mentioned is one way of compensating for expansion but there are other ways to accomplish the same thing.

[Local2ED]

Thanks for the explaination of the holes and the slots. I would expect replacements to be fine but was suprised at the differences.

Looks like I'll use the replacement.

[Local2ED]

I am hoping to start reassembling this engine this week and I did some searching on installing piston rings.

I know the ring end gaps should be staggered so they don't line up directly above each other, but should they be put in a certain position,as viewed like a clock? Top ring @12, middle ring @ 3,etc.

I remember re-building some engine years ago that told you where to position the end gaps but have not seen anything to reference the position on this engine.

Just thought now would be the time to ask.

Thank you.

[Rusty O'Toole]

I was told that if you take an engine apart the ring gaps line up with the piston pins. They work their way around to that position because of the way the piston works. So you might as well line them up when you put the engine together.

Don't know if this is true, in fact I seriously doubt it. As long as the rings don't line up they will be fine. You can randomly put the gaps 1/3 of a turn away from each other, just don't line them up.

PS some engines, Rolls Royce and Hudson among them, had a pin to hold the rings in one position. This makes me think they must move around when the engine is running.

[greg g]

Used to be a common practice to only rebore and replace cylinders with oversized pistons and rings. I remember my Uncle's 46 Pontiac had over the course of its life three ring and valve jobs and ended up with 3 standard pistons one .010 over and 2 .030 overs in it ran just fine.

By the way the jobs were done by a guy who arrived with a panel truck and did the boring with the engine in the car.

[Local2ED]

Finally got the parts back and started to reassemble the engine. I searched the forum and my service manual for the cold setting on the valves.

Seems like .014 for intake and exhaust cold is a good starting point.

Is there any disagreement to those settings?

Thank you.

[Rusty O'Toole]

Sounds a little wide to me. I think it's more like .010. In any case you are supposed to reset them hot once the engine is running.

[Local2ED]

Iwas thinking about using a copper gasket sealant/spray on the head gasket,is that what I should do?

Also since the head bolts thread into the water jacket should some type of sealant be used on the threads?

Will the sealant effect the torque readings?

Thank you.

[bri12905]

In the course of taking apart my 230cu.in. flathead in my 1958 Dodge Coronet I dropped a piston out of my hand and broke the top of the piston. I ordered a new Sealed Power #37P piston. When it arrived I noticed it did not have the verticle slot that has a hole at the termination point on the sides of the piston. Also there were less holes in the third down ring groove (8 holes on the original spaced out about 2/3 of the way around the piston VS 4 holes on the replacement, two each on opposite sides of the piston.) Everything else looked OK. What do you think about using this piston?

Thank you.

Early pistons had their skirts ground round and the T-slot compensated for skirt expansion as the piston heated up. Disadvantage: the t-slot somewhat weakens the piston skirt.

To overcome this weakness, later pistons had their skirts cam ground so the the cross-section of the skirt is an ellipse with the minor diameter in line with the gudgeon (wrist) pin. Then when the piston heated up expansion took place in line with the pin, and the skirt approached round. This is a much better design than the split skirt piston and should be chosed if at all possible. Fewer oil drain holes in the ring groove are not at all significant.

Brian