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Erndog

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My son and I pulled the 230 engine and tranny out of his 1940 sedan yesterday. We pulled the head and took a cursory look at the pistons. I scraped the carbon off of #3 and found the usual VS. However, there is also a "D" stamped on it. Does that mean anything, and if so, what?

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By the 50s Olds was using letters stamped into piston and block to identify diameters and assembly tolerances. Not sure on the earlier cars. See if there's a corresponding letter stamped into the block.

If the engine assembler saw a D stamped into the block, he would know to use a D piston. He could also use a smaller diameter piston if engine application called for say the ability to rev quickly at the expense of oil consumption. That's what they did with the "select-fit" W30 and W31 engines.

If not for assembly ID, it probably identifies the piston manufacturer.

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Ernie, what I've seen is A, B, C, D pistons and bores are considered standard size and within tolerances. E, F, G, H pistons and bores are oversize. They did this to allow for manufacturing tolerances and in the case of the larger sizes, to be able to salvage a block that might have been buggered up on the boring line.

I really need to start building up my pre-war service literature. I'm admittedly weak on it and I feel like I should be able to help pre-war guys more than I do.

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  • 3 months later...
Guest classicone64

i was wandering, were did you get the parts for the rebuild? i just got a 40 olds and what to keep it all stock, but the engine will need to be rebuilt. also do you know were to get parts catalogs for olds?

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Guest classicone64

you did your own 230 right? i have rebuilt small block chevys and big block mopar, is there anything hard about this engine to rebuild? we have an engine shop here in town that is really good so they will be checking everything out but i plan on building it myself.

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Yes, I am currently doing it. At a standstill until I can locate another camshaft spring and plunger.

The most difficult thing was getting the water tube out. This is a very common cause of these engines overheating. You can see the old vs. new on my 1940 restoration thread. It took three weeks to get it out. I had difficulty getting the valve springs out, due to them having a tall boss at the bottom. If I had been using an old fashioned compressor for flatheads instead of a "c" type compressor, it would have been much easier. The lifters were very reluctant to come out, but a can of brake cleaner fixed that. God bless brake cleaner!!

Check out the before and after pictures of the engine at:

http://forums.aaca.org/f190/1940-oldsmobile-barn-find-restoration-264780.html

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  • 1 year later...

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