40" stamped on pistons

[Inspector71]

I traded some back seats for a 68 383 block. Upon disassembling it, I saw the number 40 stamped on top of each piston. An acquaintance told me that means it has been bored. .040 over. Is that true? Any problem going to .060 over with the 383?

 

[67 coronet]

measuring your bore is the only way to be sure.most motors bored past .040 over have a tendency to run a little warm since so much metal is gone from the cylinder walls.do you need to punch it out bigger?

 

[Inspector71]

Thanks

I guess not. I was thinking about having this one stroked. I like the idea of a 438 stroker and everyone saying, "Oh, its only a 383" plus it still looks stock. I've got plenty of time to decide. I have a spare 383 block from a 69 Sport Satellite that ran great when I still had the car.

 

[Garys1969RR]

If you put a 440 crank shaft in your 383. you will come out to 426 cubic inches. Thats 3.75" stroke, and 4.25" bore. A nice combination! And with your over bore of .040 it may be 438, im not sure. I do know that the 451 motor I built works great! I like the low deck motors. They are more compact, and have to be a little more rigid I would think. Have fun with your project! Let us know how you do with it.

 

[Inspector71]

Garys1969RR

I am sorry for my tardy reply. Got busy at work. Yes, I certainly will. I have a second 383 block from a 69 Sport Satellite if I need it. I like the fact, at least I've been told this, that the stroked 383 B motor really winds out fast. The 383 seems to get no respect but I had a friend whose 69 RR 4 speed 383 was one fast car.

 

[67 coronet]

I am sorry for my tardy reply. Got busy at work. Yes, I certainly will. I have a second 383 block from a 69 Sport Satellite if I need it. I like the fact, at least I've been told this, that the stroked 383 B motor really winds out fast. The 383 seems to get no respect but I had a friend whose 69 RR 4 speed 383 was one fast car.

most"winding up fast"is achieved with lighter crank and attaching parts(pistons rods and such).its a well proven racers trick.

 

[Inspector71]

67 Coronet

Thanks for the correction. I have a lot to learn and this is the place.

 

[benno440]

measure your bore. has it been bored .40 " ??

 

[Inspector71]

Benno440

Okay, I'm new to this. What is the best tool to measure the pistons? I doubt I have it but will give it a try. I appreciate your help. Be patient, I went through the Baltimore and Philadelphia school systems

 

[Garys1969RR]

Use a cylinder bore gauge. A stock 383 has a bore size of 4.25" So .040 O S would make it 4.290" I believe. You can also pull out a piston and take it to a machine shop where they can mike it.