ID Pistons

[Drg racr]

I just can't seem to ID the new pistons in my motor. Its a 1972 360 truck motor, all rebuilt, don't know if stock or what.
The pistons are flat tops, a small indentation ring in the middle, .030 over punched on the flat top, the B-200 cast on the inside of the skirt, and some hash marks cast on the underside of the piston.
Any ideas?
I also don't see any numbers on the cam. Can I use calipers and see what the lift is?

 

[d55dave]

Probably stock replacement pistons. A picture would help. Stock 360 pistons are "dished". You cannot properly measure the cam without putting a dial indicator on a lobe and rotating it.

 

[70aarcuda]

there are some stock oem 360 pistons that were flattops...not dished.

 

[swinger340]

there are some stock oem 360 pistons that were flattops...not dished.

Yes. I have some STD OEM pistons out of a 71 360. They are 4 valve relief flat tops that sat .080 or better below the deck

 

[d55dave]

I stand corrected - thanks for the info!

 

[RustyRatRod]

Yes. I have some STD OEM pistons out of a 71 360. They are 4 valve relief flat tops that sat .080 or better below the deck

Then they are replacements. The 71 360 had flat tops with no reliefs. Also, they had a taller compression height than any other year.

To the OP, you cannot measure cam lift with calipers. You have to either measure it with a dial indicator in the engine, or put the cam on v blocks on the bench and use a dial indicator. Because the cam manufacturer could have put the lobes anywhere on the cam core they wanted in relation to the cam center line. I keep preaching this over and over, but no one ever seems to listen.

 

[Drg racr]

Yeah, they're probably stock replacements. I'll end up replacing them. It's already bored .030 over, not a lot more room to go.

 

[swinger340]

Then they are replacements. The 71 360 had flat tops with no reliefs. Also, they had a taller compression height than any other year.

To the OP, you cannot measure cam lift with calipers. You have to either measure it with a dial indicator in the engine, or put the cam on v blocks on the bench and use a dial indicator. Because the cam manufacturer could have put the lobes anywhere on the cam core they wanted in relation to the cam center line. I keep preaching this over and over, but no one ever seems to listen.

Just went out to confirm, and you are correct. The 71 360 pistons have no valve reliefs. I must have been thinking about the 72 340 pistons I also have.

 

[RustyRatRod]

Just went out to confirm, and you are correct. The 71 360 pistons have no valve reliefs. I must have been thinking about the 72 340 pistons I also have.

I'm not gonna say "never" but I don't think the 360 ever came with a 4 eyebrow piston stock. I've never seen one yet......not that that's any indication. lol

 

[Drg racr]

I don't like the fact that the pistons sit .095 below deck height. I'll probably get the KB107's or similar, and shave a set of J heads. We'll see if that gets me closer to the 9.8:1 compression I'd like to be at.