Pistons

[okiebob]

I pulled the 259 out of my 60 Lark to try and slow down the oil leaks. Pulled the heads to do a valve job. After cleaning the top of the pistons they had numbers stamped on them. This is the bore size right? The thing is six of them were 30 over and numbers 2 & 7 were 25!? I've never heard of a 25 over. Can anyone clue me in as to what this means. Are there any tricks to slow the oil leaks to at least a drip every once and while instead of the puddle I get every time it's parked? Thanks, OkieBob


I LOVE MY STUDEBAKERS

[Roscomacaw]

Have you actually measured the bores or the piston, Bob?

Miscreant at large.

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe
1957 President 2-dr
1955 President State
1951 Champion Biz cpe
1963 Daytona project FS

[whacker]

As far as oil leaks go, the main places to seal up are the valve covers, the oil pan and the distributor. Front and real seals often leak, but my experience has been that they get blamed for a lot of leaks that really originate elsewhere. If your distributor is leaking at the block, the oil will run down the back, around the side of the bell housing and drop off at the lowest point - this looks like a rear seal leak, but isn't. Oil leaking out of the heads (if the return passages are clogged with sludge), will do the same thing, again looking like a rear seal. Use the thick, neoprene valve cover gaskets, and glue them into the ridge aroud the edge of the valve cover. While you have them off, be sure the return passages are clean. The oil pan, with all the small pieces, is not easy to seal. The best way to do the pan is with the engine upside down on a stand. Use lots of Permatex. Don't use silicon.

[blackhawk]

quote:As far as oil leaks go... Use lots of Permatex. Don't use silicon.

Whacker, why? I have used the blue automotive silicone many times on my Studebakers (or the red silicon whre heat was a factor). I was able to completely stop the oil leaks on my '64 Cruiser for many years after replacing the pan gaskets with the car on stands using silicone in addition to the gaskets. My dad was a mechanic and always claimed that Permatex would harden the seals in the engine and so advised using it sparingly. Course that was a long time ago. Their product could be better nowadays. Course, he could have been wrong too. But, I know the silicon works. Dale

[JDP]

Isn't that the mark for factory tiny over sizes of .0002 or 00025 for piston fitting ?

Arnold Md.
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64 Daytona HT
63 R2 4 speed GT Hawk
63 R1 GT Hawk
63 GT Hawk
63 Avanti R1/AC
63 Avanti R2/4 speed
62 Lark 2 door
60 Hawk
51 Commander

[Dwain G.]

Your engine is still standard bore. When it was assembled at the factory, pistons were selectivly fitted to the bores. Not every bore on every engine was exactly the same. The cylinder bore could range from 3.5625 (3 9/16" exactly) to 3.5645 .002" oversize). What you are seeing is the last two numbers. '30' is .0005" more than '25'. The same numbers can usually be seen on the block next to the cylinder. Factory says no one engine will have more than .001" variation. Of course after several thousand miles and a little wear these numbers no longer mean a thing!

Dwain G.

[hank63]

Well, I've also had considerable success with the blue silicon as gasket replacement. And I'm talking about stopping oil leaks in old British cars. That's just about the worst leakers you can find. The trick is to carefully de-grease any surface to get the silicon. Can be a bit of a job to split the joint later.
/H

[farmhawk]

This is great. I have a 289 still in the original crate and all eight of the pistons are marked with 30. I asked around and most people felt it was for 30 over, and a rebuild. But there is a Studebaker tag in the crate ssaying it was manufactured in 1962. So I guess this is a new motor after all! Thanks

61 Hawk