Author Topic: 69 Z28 Ring gaps????  (Read 3250 times)

regardstobuck

  • Newbie
  • *
  • Posts: 1
    • View Profile
69 Z28 Ring gaps????
« on: September 29, 2007, 09:04:05 PM »
Hey guys does anyone know what would be correct ring gaps for an original DZ302. I have heard anywhere from .013 up to .023. any clarification would help.

thanks in advance

hotrod68

  • Hero Member
  • *****
  • Posts: 520
  • almost finished
    • View Profile
Re: 69 Z28 Ring gaps????
« Reply #1 on: September 30, 2007, 03:13:17 AM »
The general rule is .004" for every inch of bore with forged pistons for a street engine, i.e. a 302 with a stock 4" bore would have a top ring gap of .016-.018". .013" is way too tight if you really lean on the engine and like scored cylinder walls. Different applications need different gaps--as a hot race or street/strip engine would require .002-.004" more gap per inch of bore with nitrous or a supercharger. The best way is to FOLLOW THE RING MANUFACTURER'S INSTRUCTIONS. If you really want to blueprint things, buy some double moly rings .005" oversize and file-fit them to the exact gap. That way you know you're right. For my 2 cents, I'd gap your rings at .018" and spin that 302 screaming at 7000! Good luck!


 
HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
Butternut Yellow    black standard interior

JohnZ

  • CRG Member
  • *****
  • Posts: 4365
    • View Profile
Re: 69 Z28 Ring gaps????
« Reply #2 on: September 30, 2007, 05:32:29 PM »
Also follow the instructions from the PISTON manufacturer; many hypereutectic pistons have very specific requirements for wider-than-normal gap on the top compression ring.
'69 Z/28
Fathom Green
CRG