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

Holly Help!!!!!!!

  • Thread starter Thread starter sand1man
  • Start date Start date Aug 11, 2005

sand1man

Founding Member
May 14, 2002
299
0
0
Charlotte, N C
Aug 11, 2005
#1
  • Aug 11, 2005
  • #1
Holley Help!!!!!!!

heres what I have, A Holley 650 DP, I blew the power valve a while back and finally got around to fixing it, I put a plug in it and heres my problem.

1. at idle the car is running rich according to a/f gauge, do I adjust this with jets or is there a different way for idle??

2. at cruising speed it runs rich but not as bad as when idleing, same question here, jets or adjustment screw?

3. last but not least I currently have 88 as the secondary jets, any idea on what I need to go up to since I plugged the powervalve.

Thank you for all the help.
 

sand1man

Founding Member
May 14, 2002
299
0
0
Charlotte, N C
Aug 11, 2005
#2
  • Aug 11, 2005
  • #2
sorry about the title, just realized what I wrote
 
G

grego37

New Member
May 12, 2004
576
0
0
Fresno CA
Aug 11, 2005
#3
  • Aug 11, 2005
  • #3
when you plug a powervalve, you're supposed to compinsate by going up 6 jet sizes.

To adjust the air/fuel mixture for the richness at idle. Get the car to normal operating temp. and turn the air/fuel mixture screws until the highest idle is achieved, or you can hook up a vacuum gauge and shoot for the highest vacuum reading. Then bring your main idle back to desired rpm.

If it runs rich or lean at crusing speeds thats where jet changing comes into play. you can do a plug read test.
 

sand1man

Founding Member
May 14, 2002
299
0
0
Charlotte, N C
Aug 11, 2005
#4
  • Aug 11, 2005
  • #4
thanks for the info that pretty much what I needed to know
 
F

ForceFed70

That's why they call it "dope"
Founding Member
Dec 6, 1999
4,818
1
69
BC Canada
Aug 11, 2005
#5
  • Aug 11, 2005
  • #5
There should be a scew to adjust/controlled idle mixture.

Cruising mixture is adjusted/controlled by jetting.

Acceleration mixture is controlled by the accelerator pump and cam.

Full throttle mixture is controlled by power valve.
 
You must log in or register to reply here.

Similar threads

G
Need tuning help with 4100 Carburetor
  • Gary’s 67
  • Aug 18, 2026
  • 1965 - 1973 Classic Mustangs -General/Talk-
Replies
5
Views
230
1965 - 1973 Classic Mustangs -General/Talk- Aug 22, 2026
manicmechanic007
H
Holley Carb Tuning Help
  • hassler
  • Oct 25, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
6
Views
437
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Oct 29, 2025
85GTStangGuy
D
66 Coupe Progress Thread
  • DTCRAWLEY
  • Apr 19, 2026
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • 2 3
Replies
43
Views
2K
1965 - 1973 Classic Mustangs -General/Talk- Jun 17, 2026
DTCRAWLEY
D
K
Electrical 2000 GT Intermittent Engine Shutdown In Motion - DTC U1262
  • kenster1092
  • Apr 13, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
308
SN95 4.6L Mustang Tech Apr 24, 2026
squeak93
I
Engine Help requested in identifying how to resolve engine light issue
  • Ianslaney
  • Oct 4, 2026
  • SN95 4.6L Mustang Tech
Replies
1
Views
149
SN95 4.6L Mustang Tech Oct 4, 2026
Bullitt347
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?