Hi there!
I’ve jsut bought a return spring bracket from holley for my 390GT engine.
But i need longer studs to bolt it on the carburetor.
What size are they ? I’m terrible with threads sizes and imperial for that matter.
here a pic of the current setup
The Ford carb studs have two different thread sizes:
5/16" x 18 (bottom side threads into the intake)
5/16" x 24 (top side for carb nut)
The top side length depend on the spacer thickness.
These parts are available from Mansfield Mustang:
Engine, Fuel/Carburator Page 1
Thank you !
Is it 5/16"x 18 mm ? or 18 inches ?
So to accomodate my new bracket i’d need a stud longer than 24
The thread pitch is 5/16" by 24 threads per inch (NF) on the top side. This does not in any way refer to the length of the stud. Proper studs are sold at Mansfield Mustang as Vic says.
You have the return spring bracket upside down and the return spring located improperly. It should be like this:
(thanks to the 428CJ.com website)
oh really ? It was like this when I bought it and never questionned it ! I’ll try it this way see if it makes a difference
Royce - Have you found a source for the correct bracket as shown in your picture? The Mansfield part has an extra bend and is longer than my original.
Vic Yarberry
Cougars Unlimited LLc
The link that Royce posted takes me to “metropolitan supply”.
This seems to happen sometimes with links posted here, guess that the bad actors have figured out a way to highjack them 
- Phillip
Thanks Royce for the link to the 428CJ website - it notes that two different style brackets were used.
The bracket I’m looking for is the one from your first picture. It is a “L” bracket.
The 1968 Ford MPC lists two brackets:
C7OZ-9741-B 1967 390, 1968 427/428CJ (reproduction available, 2-angle style)
C8ZZ-9741-A 1968 390 “L” bracket style
(from the 1968 assembly manual)
Note that the notch/stop tang is on the opposite of the bracket.
(picture from The Best 1968 Shelby Webpage !!!)
The bracket with the tang on the inside (towards carb) cannot be used on an aftermarket Holley carb does not have the ridge found on original carbs (i.e. 3310). I believe the “L” bracket style was used on early cars, like my Dec 6, 1967 built 390 GT.
Looks like something you could make easily.