Ever seen a piston like this?

[crucial118]

Wasup? These pistons are in a block that I just bought. It is a 1974 SBC 400. Everyone I show this pic to ask "What the hell is that?" And I can't answer. I have only built 2 motors, so I don't have much knowledge in what else is out there, but the people who asked what it was were both very knowledgeable when it comes to wrenching. Just wonder if anyone else has seen these before and why are they like that? Something from the smog era, I don't know. Thanks.

 

[chevy2480]

That looks to be a stock 400 dished piston with 4 valve reliefs. Thats generally how all 400 pistons where. There where also 2 different cc pistons some where higher compression.

 

[crucial118]

What is the cut out for?

 

[chevy2480]

What is the cut out for?

Valve relief. Or aka piston to valve clearence. Thats what the 4 notches are 4. Why 4 I never understood. Some 350 pistons are the same way.

 

[gwhiz]

What is the cut out for?

I dont think it does anything other than give a referrance on orientation for installation.Those just look like chevy pistons to me i got a 91 350 with similar pistons.

 

[gwhiz]

What is the cut out for?

I dont think it does anything other than give a referrance on orientation for installation.Those just look like chevy pistons to me i got a 91 350 with similar pistons.

sorry wanted to clarify the 4 indentations are valve reliefs and the "cut" or notch is for instalation referance.

 

[crucial118]

Yeah, I understood what the 4 eyebrows were for(valve relief), but had no idea what the notches were for. I guess I should have clarified my question.

 

[chevy2480]

If your talking about the notch next to the dot. That indicates the direction the piston goes. They face the front of the motor.

 

[crucial118]

If your talking about the notch next to the dot. That indicates the direction the piston goes. They face the front of the motor.

Yup that's what I was talking about. Never seen one before and it was funny that a couple other people I know never has seen them before. I thought they were only on 400s or something. Thanks.

 

[crucial118]

Valve relief. Or aka piston to valve clearence. Thats what the 4 notches are 4. Why 4 I never understood. Some 350 pistons are the same way.

4 eyebrows so that it can be installed on both the pass and driver's side with the notch facing forward makes sense.