• Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

How to read compression test results?

  • Thread starter Thread starter gideup
  • Start date Start date Apr 25, 2004

gideup

Member
Dec 28, 2002
114
0
17
fort myers, fl
Apr 25, 2004
#1
  • Apr 25, 2004
  • #1
Just got my first antique 1965 2 +2 mustang with a 289 motor. Did a compression test to see where things are.

Low was 130, high was 145, with average of 134.5 over all eight cylinders.
Not sure if this is OK, so-so, or acceptable.
any thoughts from you restomoders out there?
 
R

Ronstang

New Member
Apr 4, 2004
1,294
0
0
Houston Texas
Apr 25, 2004
#2
  • Apr 25, 2004
  • #2
It isn't terrible, but it isn't great. Some people say that all cylinders need to be within 10%, which your's barely is, and some say 5%. If it runs ok then let it go until you have the time and $$$ to do a quality rebuild.
 
A

akd67

Banned
Apr 6, 2003
231
0
0
Small Town Illinois
Apr 25, 2004
#3
  • Apr 25, 2004
  • #3
It isnt the #s but how consistant they are. 10% of each other is what you are looking for.I checked mine pulling one plug at a time (I now know the correct way) and got close to 140 in all but one, which was 0. Push rod was bent bad.Is yours running ok?
 

gideup

Member
Dec 28, 2002
114
0
17
fort myers, fl
Apr 25, 2004
#4
  • Apr 25, 2004
  • #4
it starts right up, I put new plugs in today. It runs kind of rough, could be that it needs new wires. If youjump on it, wants to stall. The gas is old too. The point gap is right on, but the carb hookup is kind of rigged. I have not had a chance to check the timing.
 
You must log in or register to reply here.

Similar threads

D
Engine Questions on compression test results
  • dqureshi06
  • Jan 6, 2025
  • Fox 5.0 Mustang Tech
Replies
5
Views
387
Fox 5.0 Mustang Tech Jan 7, 2025
Noobz347
Engine 1994 5.0 refuses to idle
  • FordFanatic1894
  • Jul 20, 2025
  • 1994 - 1995 Specific Tech
Replies
14
Views
482
1994 - 1995 Specific Tech Jul 22, 2025
General karthief
S
5.0 Rebuild
  • smittys7up
  • Nov 29, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
8
Views
525
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Dec 20, 2025
Noobz347
D
Brakes 1966 Mustang convertible 289, Auto - Disc brake conversion issues
  • DRGunn427
  • Feb 26, 2025
  • Classic Mustang Specific Tech
Replies
1
Views
538
Classic Mustang Specific Tech Mar 13, 2025
dmzenge
D
K
Engine 2000 Mustang GT - Fuel issue post-blown spark plug repair
  • kenster1092
  • Feb 26, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
290
SN95 4.6L Mustang Tech Mar 10, 2026
kenster1092
K
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific 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?