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Author Topic:   Ring end gap various theories ??
Pierre
Gearhead

Posts: 357
From: France
Registered: Apr 2002

posted 02-24-2003 11:41 AM     Click Here to See the Profile for Pierre   Click Here to Email Pierre     Edit/Delete Message   Reply w/Quote
Hello guys, I usually post in the classic section but this topic may be more appropriate here:

Seems like there are several ring-end-gap theories out there & kinda going opposite directions:
some say that the top ring should have the biggest gap since it is the first one to take the beating & the heat (therefore expansion)
(ie: 0.018-0.020 first ring & 0.014-0.016 second ring for a 4.030 302)

& that makes sense.....

Others say that in order to prevent ring floating (making sure that the top ring stays seated at the bottom of the first groove at all time) & inter-ring pressure build-up, the first ring should be set tight (ie: 0.014-0.016/First & 0.020-0.022/second)

And that makes sense too

What do you guys think of this ?

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Ryan Wilke
Gearhead

Posts: 1501
From: Stanton, Michigan 49707
Registered: Oct 2000

posted 02-24-2003 01:22 PM     Click Here to See the Profile for Ryan Wilke   Click Here to Email Ryan Wilke     Edit/Delete Message   Reply w/Quote
Pierre,
IMO, for a limited use, normally-aspirated race engine using forged pistons, I'd use a moly-coated ring on top and a plain cast-iron ring on second....I'd carefully file-fit them both at 0.018" - 0.022".

My 2 cents,
Ryan

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Moneymaker
Administrator

Posts: 19704
From: Lyons, IL, USA
Registered: May 99

posted 02-24-2003 07:01 PM     Click Here to See the Profile for Moneymaker   Click Here to Email Moneymaker     Edit/Delete Message   Reply w/Quote
Last time I looked (about a minute ago)there were quite explicit, and specific ring gap instructions in the box.
Why would you want to deviate from the ring manufacturers recomendations? Especially on a street car?

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Alex Denysenko
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Pierre
Gearhead

Posts: 357
From: France
Registered: Apr 2002

posted 02-25-2003 05:27 AM     Click Here to See the Profile for Pierre   Click Here to Email Pierre     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Moneymaker:
Last time I looked (about a minute ago)there were quite explicit, and specific ring gap instructions in the box.
Why would you want to deviate from the ring manufacturers recomendations? Especially on a street car?


Well, being new to this hobby I have actually never touched/seen a set of ring nor the box it comes in & I try to be very cautious about every steps (may be too much sometime, all right )

I have received the gap specs from my piston manufacturer speed pro (mail I sent you and you OKed them) & it seems to be opposite to the one of the ring manufacturer that summit gave me over the phone later on !

I will mostelikely cover my *ss and follow the specs of the ring manufacturer but returning a broken engine ain't cheap to me so I am trying to understand why specs can differ so badly !!


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V8 Thumper
Gearhead

Posts: 3467
From: Orange, Ca. United States of America
Registered: Dec 2001

posted 02-25-2003 07:28 AM     Click Here to See the Profile for V8 Thumper   Click Here to Email V8 Thumper     Edit/Delete Message   Reply w/Quote
Hmmmmmmm, I've also heard lately (for the first time) about the 'tight' top ring ...

I figure that the manufacturer knows a helluva lot more about metalurgy than I do, so I've always gone with the 'looser' top ring as per spec

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Moneymaker
Administrator

Posts: 19704
From: Lyons, IL, USA
Registered: May 99

posted 02-25-2003 09:56 AM     Click Here to See the Profile for Moneymaker   Click Here to Email Moneymaker     Edit/Delete Message   Reply w/Quote
As much as I like Summit, I would rather trust info right from the manufacturer Pierre.
Go with my previous recomendations.

------------------
Alex Denysenko
Co-Administrator and Moderator

NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00,'01,'02,&'03
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl

Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com

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D&S Induction Systems
Gearhead

Posts: 118
From: Columbia Heights Mn U.S.A.
Registered: Feb 2003

posted 02-25-2003 01:26 PM     Click Here to See the Profile for D&S Induction Systems   Click Here to Email D&S Induction Systems     Edit/Delete Message   Reply w/Quote
I like Summit too, because of there prices but I can't stand there Tech's.

Any way, depending on the type of engine you have and what you are going to be using it for, determines what you should set you're "ring-end gap" to.

As somone stated before, the top compression "ring-end gap" should be greater than the 2nd 3rd etc. The main reason for this is heat and piston movement.

The top piston ring is going to see more heat than the other rings because it's closer to the flame. Also, when the piston rocks back and forth in it's bore, the top ring is subjected to more movement than the other rings.

As far as what to "gap" the rings to.

In a 4" bore...Top ring

-supercharged
.022-.024

-Normally aspirated
Street-strip .016-.018
Nitro-street .024-.026
Nitro-drag only .032-.034

2nd ring

Supercharged
.012-.014

-Normally aspirated
Street-strip .010-.012
Nitro-street .018-.020
Nitro-drag only .024-.026

*Note: These specs. are not set in stone. There are other factors that come in to play, but it gives you a good idea on what to set you're ring-end gap to.


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