340 ring gap?

[spoolinhard]

I have a freshly bored 340 (.030 over) with TRW forged stock replacement pistons. I am using Hastings moly rings.  TRW has been sold, info is not available. Hastings does not have any info on their website. I have sent them an email and received nothing in response? What king of endgap do I need on my Compression/ oil rings?
thanks

[Jim AAR]

From the Plymouth Service Manual – Page 9-39, You can download from this website

All the Manuals are here: https://www.e-bodies.org/resources/service-manuals-parts-catalogs-tsb/

Fitting Rings
(1) Measure piston ring gap about two inches
from bottom of cylinder bore in which it is to be fitted
(An inverted piston can be used to push the rings
down to insure positioning rings squarely in the cylinder
bore before measuring).
(2) Insert feeler stock in the gap. The ring gap
should be between .010 and .020 inch for compression
rings and .015 to .062 inch for oil ring steel rails in
standard size bores (for new service rings). Maximum
gap in .005 inch 0/S bores should be .060 inch for
compression rings and .070 inch for oil ring steel
rails.
(3) Measure side clearance between piston ring and
ring land (Fig. 41). Clearance should be .0015 to .003
inch for the top compression ring and the intermediate
ring. Steel rail service oil ring should be free in
groove, but should not exceed .005 inch side clearance.
(4) On 318 Cubic Inch Engine, the keys on the
spacer expander must be inserted into the hole in the
oil ring groove over the piston pin front boss.
On 340 Cubic Inch Engine, install the spacer keys
into one of the drain holes on the outboard side of
the engine.
(5) Install compression rings in middle and top
grooves use ring installer Tool C-3586 for 318 cubic
inch engine, Tool C-3672 for 340 cubic inch engine.
Be sure the mark "Top" on each compression ring is
to the top of piston when ring is installed.

[Chryco Psycho]

 I use .004 / 1" of bore so .017 minimum & I like to be close to minimum to minimize blow by .
Make sure the rings have the gaps 120-180* apart when you install the pistons 

[jimynick]

The old standard was, as Neil has said, .004" per inch of bore, but things have been changing and it also depends on your application. Is the car ever going to see boost or turbocharging? Many of the articles I've read have indicated that they're now enlarging the second ring gap as opposed to the top ring as in days of old. I'd contact TRW and see if their tech boffins have any recommendations, too. Just my 

[Chryco Psycho]

Boost would change things !

[RUNCHARGER]

Yes: Last engine I built I enlarged the second ring gap after speaking with Tim at FHO, it worked well. However you can't go wrong with the factory recommendations either.

[spoolinhard]

It is a stock rebuild, stock specs work great. Thanks!

[MOPAR MITCH]

https://www.hastingspistonrings.com/contact/

Contact the Hastings Tech Line... since you're using their rings.  They will ask you the SET number... they sell pre-gapped rings...as well as file-to-fit rings.