Jahns Pistons part# 1157

**chevyandpontiac** · #1 07-26-2016, 11:14 AM

I am trying to find out if these are open or closed chamber pistons.

I know they are 1965-1970 396 standard bore, 12.1 CR

Thanks Dan

**earntaz** · #2 07-26-2016, 04:01 PM

CLOSED ... I believe open chambers began about 71' ... TAZ

**67 Nova Boy** · #3 07-26-2016, 04:29 PM

LS6 454 were open chamber heads so maybe even 1970 so as Taz said...closed

Dave
67 Nova Boy

**chevyandpontiac** · #4 07-26-2016, 05:33 PM

Thanks everyone.

**earntaz** · #5 07-26-2016, 07:35 PM

Dan -- I just looked at a set of 1157's on EBay ... they are closed chamber pistons. TAZ

**67 Nova Boy** · #6 07-26-2016, 08:50 PM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: earntaz</div><div class="ubbcode-body">Dan -- I just looked at a set of 1157's on EBay ... they are closed chamber pistons. TAZ </div></div>

Taz...are the piston domes kidney shaped like the head?

Dave
67 Nova Boy

**earntaz** · #7 07-26-2016, 09:13 PM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 67 Nova Boy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: earntaz</div><div class="ubbcode-body">Dan -- I just looked at a set of 1157's on EBay ... they are closed chamber pistons. TAZ </div></div>

Taz...are the piston domes kidney shaped like the head?

Dave
67 Nova Boy</div></div>

Yes they are ... and look like at least a 12:1 CR ... TAZ

Dedicated to the Promotion and Preservation of American Muscle Cars, Dealer built Supercars and COPO cars.