• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Engine 302 rebuild Piston Ring gap

  • Thread starter Thread starter 88foxy
  • Start date Start date Apr 7, 2021
8

88foxy

New Member
Oct 6, 2020
4
0
1
St. Louis
Apr 7, 2021
#1
  • Apr 7, 2021
  • #1
Rebuilding the 302. First on my own build and ust got the block back from the shop. .020 over bore.

Got the cam and crank installed last night with new bearings. Went to move onto the pistons today. Assembly was balanced at the shop. Running stock crank, rods w/ ARP studs, Summit Racing SUM-17370FC-20 - Summit Racing® Coated Forged Pistons, Sealed Power E-251K20 - Sealed Power Performance Piston Rings.

Was checking ring gap today. Seems like it’s all over the place and this is what I got. (Double checked)

#1. Top - .021, Bottom - .018
#2 Top - .020, Bottom - .017
#3 Top - .020, Bottom - .017
#4 Top - .021, Bottom - .017
#5 Top - .023, Bottom - .019
#6 Top - .023, Bottom - .020
#7 Top - .023, Bottom - .018
#8 Top - .024, Bottom - .020

This is a street build. Plan on eventually running boost down the road as well. Rings did not come with a reference sheet. I’ve read .004 per 1” of bore is ideal. For boost, I’ve read .005-.0055 per “1 of bore. Also I’ve read the bottom ring should be .002-.004 bigger than top ring.

My question is, did I get a bad set of rings? Bad bore job? Should I file? Swap rings around into different cylinders? Buy a different set of rings and try again?

Just want to make sure I’m getting this correct and to have a healthy motor. Thanks in advance!
 

HemiRick

I'd be looking at jacking under the house
Jun 28, 2020
723
272
73
Memphis TN
Apr 13, 2021
#2
  • Apr 13, 2021
  • #2
Thats not all over the place....just looks like the 2nd rings need to be filed.
 
You must log in or register to reply here.

Similar threads

6
Hey all,I’m putting together a 302 for my 1968 Mustang and wanted to post the combo + some questions to make sure I’m not missing crucial
  • 68_Disgustang
  • Feb 22, 2026
  • 1965 - 1973 Classic Mustangs -General/Talk-
Replies
3
Views
691
1965 - 1973 Classic Mustangs -General/Talk- Feb 28, 2026
Noobz347
S
Requesting Guidance for 306 motor swap - Fuel? - SD? MAF?
  • So_Flo
  • Jul 26, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
32
Views
2K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jan 4, 2026
Mcmahst
Engine 302 production block selection
  • FastDriver
  • May 19, 2024
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
48
Views
7K
Fox 5.0 Mustang Tech Jul 1, 2025
FastDriver
Ring gap too excessive?
  • PDHSB
  • Sep 13, 2021
  • SN95 4.6L Mustang Tech
Replies
4
Views
1K
SN95 4.6L Mustang Tech Sep 23, 2021
Hoytster
G
Fox "Piston ring gap really does not matter that much"
  • Gnfanatic
  • Mar 8, 2022
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
7
Views
4K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- May 8, 2022
BrewsterGT
B
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?