[Brutpwr]

Ok I need to set the end gaps on my Supercharged small block Chevy. Reusing my old Weisco pistons. I believe that I set the original gaps at .022 top and .018 bottom before without incident. So that is what I set the Speed Pro rings at. But now I just see the instructions for Speed Pro call out for .024-.026 top and bottom. So I know that is a safe bet but I have them set perfect at .022 top and .018 bottom and would like to keep it tight if possible for best longer life etc. Also I see that Speed Pro recommends a larger gap on the second ring as recent testing has shown a better seal doing it this way. This is the first I've heard of this but I've see there point where they say the larger escape path prevents the top ring from lifting up from pressure build up between the rings. What do you use for gaps and what would you do with bottom gaps...I'm may be old school in thinking the gap on the bottom can be tighter as the heat and thus expansion (closing of the gap) will be less. Let me know ASAP as I'm ready to install the pistons and of course Weisco is closed. I lost my Weisco original instructions. Going to try their web site now... Engine is a 355 Chevy (B&M roots style blower) with 450+ HP at the crank.

Thanks,
Jason

 

[Terranaut]

Have you considered a full sealing ring where the 2 ends overlap?
This take the guesswork outa setting ring gap. I have used them but not with forced induction.
Just a thought.

 

[Brutpwr]

I know the gapless ones are good and considered them but they are more expensive and I was not sure they would work well with a supercharger. I thought I may have read some where that they are not recommended with Turbos or Superchargers so I would love to hear from those that have used them--especially leak down tests before and after etc.

 

[MrWillys]

Man, I'd really want to stick with Speed Pro recomendation. I do know that the Plasma Moly ring is a soft metal with a very short seat period. Could the soft metal expand more? Requiring the already stated increased gaps? A little bit of filing will assure that they won't meet.

 

[Brutpwr]

ttt...need help...calling Weisco tommorrow (ok today this mourning)

Jason

 

[gumbojeepyj]

the ring manufacturer's recommendation is what I would do.

 

[Brutpwr]

We put them in at the settings we used last time....022 top and .018 bottom. Did not get a chance to call Weisco as I was busy running around all day at work. Did email them so hopefully I'll get an answer back from them in the next day or two.

Jason

 

[Brutpwr]

Weisco sent me an email stating that yes their ring spec is .022 top and .018 bottom. But they sugguest as many here have that in this case the Speed Pro ring specs would be the best safest route. I already installed these in the engine and I hate installing pistons I'm going to ask for more opinions--I talked to experienced engine builders and they both thought the .022 and .018 should be ok. One guy has a $300,000 record holding drag rail so I know he has seen what works and what will not--his rail is set up at .022 and .018 same as ours engine and we don't make anywhere near the power he does!

Jason