ID’ing my pistons and crank

[340inabbody]

This is my old 318 that I had sitting around. I’m curious about what I have here. The Pistons look to be aluminum and the crank I believe is forged. But you guys are a much better group to determine that then I am so here are some pics. Let me know what you think.

 

[TT5.9mag]

All pistons are aluminum. All cranks are steel. It’s the process with which they are made that defines them.

Forged aluminum
Cast aluminum
Hypereutectic aluminum
Billet aluminum


Cast steel
Forged steel
Billet steel

 

[TT5.9mag]

What year is your 318?

 

[340inabbody]

It’s a 1970 and I just saw the wide forging pad on the crank seen here. So it’s probably the original forged steel crank. I didn’t want to assume anything. What about the pistons? Do these look original? I think the motor was rebuilt?

 

[TT5.9mag]

I couldn’t see a parting line in your first post that’s why I asked the year. 70 was definitely a forged crank and cast pistons. Those look to be original (style) pistons. If they’re over sized it’ll be stamped on the top, you’ll have to clean the carbon off of em to see it.

 

[str12-340]

sorry but if this were an original crank in a 1970 318 it would be cast not forged, unless it is an odd HD truck 318. The original pistons at 8.8:1 compression had no valve recesses. The good news is that - that probably means the engine was rebuilt and upgraded at some point. This part is relying on shaky memory, but I believe that the original pistons, even for a 340 and 273HP, only had valve reliefs on one side of the piston (the factory only installed the off center pin pistons (to reduce piston slap/engine noise) in one direction), so no need for both sides. I believe most replacement pistons with valve reliefs had ones on both sides.

 

[340inabbody]

That wide forging pad is indicative of a forged crank. As opposed to a thin parting line from a casting. What about the drilled holes? That implies internally balanced right?

 

[forphorty]

All pistons are aluminum. All cranks are steel. It’s the process with which they are made that defines them.

Forged aluminum
Cast aluminum
Hypereutectic aluminum
Billet aluminum


Cast steel
Forged steel
Billet steel

Actually, cast iron and cast steel are not the same thing.

 

[340inabbody]

Sorry guys I had a typo in my initial post. Looking at the parting line being so wide it looked like this is a forged crankshaft. Can anyone confirm this by their experience? I don’t have any experience looking at a lot of these.

 

[Oldmanmopar]

Its a cast crank with after market pistons. Now I would determine what rods were used. 340-318-360 , 340 Floating or 318-360 pressed pins. measure the width of the beam. 360 rods are wide but have pressed pins also. The engine was definitely rebuilt with new pistons. But that looks like a cast crank to me from looking at whats shown.

 

[340inabbody]

Its a cast crank with after market pistons. Now I would determine what rods were used. 340-318-360 , 340 Floating or 318-360 pressed pins. measure the width of the beam. 360 rods are wide but have pressed pins also. The engine was definitely rebuilt with new pistons. But that looks like a cast crank to me from looking at whats shown.

Why do you think that it’s cast? That parting line is over 1/4”.

 

[340inabbody]

Another clue? Is this harmonic balancer 0 balanced? I see holes drilled in it I presume for balancing?

 

[lilcuda]

Forged crank with cast pistons. Have to get a real close look to see if they are aftermarket or not. Best way is to do a quick measurement of one of the bores with calipers to see if it’s standard or not.

 

[340inabbody]

Pistons have a number as well. B285 looks like a 60 over piston from a co called Bagger?

 

[lilcuda]

Pistons have a number as well

View attachment 1716490876

Looks aftermarket to me. Company is called Badger. Cheap rebuilder pistons.

 

[Max1196]

Its a cast crank

NOT cast, it's forged

 

[Newbomb Turk]

That wide forging pad is indicative of a forged crank. As opposed to a thin parting line from a casting. What about the drilled holes? That implies internally balanced right?

The crank is forged, the pistons are OE replacements.

As to the claim that 318’s had cast cranks I’ve opened up many virgin 318’s and I bet I was into the 20’s before I found one with a cast crank.

So most likely it’s the crank it rolled out of the factory with.

 

[Newbomb Turk]

Looks aftermarket to me.

It’s factory.

 

[Newbomb Turk]

Another clue? Is this harmonic balancer 0 balanced? I see holes drilled in it I presume for balancing?

View attachment 1716490871

I don’t remember a factory damper with that many holes in it but it’s certainly a forged crank damper.

I suspect because it’s a 318 and the pistons are lighter the factory balance required that.

Rest assured it’s a steel crank. And I’d bet a bunch it came from the factory with it.

Edit: the pistons appear to be Badgers. For what they are there is nothing wrong with them except the compression ratio is pretty low.

 

[lilcuda]

It’s factory.

Not the crank, the piston.

 

[Newbomb Turk]

Not the crank, the piston.

Aftermarket replacement piston.

 

[lilcuda]

Aftermarket replacement piston.

Yes, I know. Spent 10 years as a machinist. Very familiar with Badger pistons.

 

[sr71mopar]

Forged. What from?

 

[TT5.9mag]

Actually, cast iron and cast steel are not the same thing.

I know. I didn’t say they were the same.