• Hello there guest and Welcome to The #1 Classic Mustang forum!
    To gain full access you must Register. Registration is free and it takes only a few moments to complete.
    Already a member? Login here then!

Carburetor retaining nuts

70 StangMan

70 StangMan

Well-Known Member
Donator
I've got sneaky feeling that my carb. retaining nuts are vibrating loose (slightly) when I fire up the car and go for a drive. Don't know for sure but plan to find out Friday. If that is the case what is the best method to stop it ?? Thread-lock? Lock washer ?? :shrug
 
Are you not using at least lockwashers? That's what I use and never have my nuts gotten loose.....
 
"cmayna" said:
Are you not using at least lockwashers? That's what I use and never have my nuts gotten loose.....
Click to expand...
Nope...Nada ..nothing. Never had a problem until I put on the new carb., now it seems they are backing off.
 
I'd using split lockwashers too, plus a flat washer under that so the split washer does not gall the alum carb.
 
I only use a flat washer under the nut and torque to spec. Never had one loosen up on me.
 
If it's fine thread like the ARP's on the wifes car, then it's 5/16-24.


Sent from my iPhone using Tapatalk
 
A 1/2 nut to hold the carb down?? Are you talking the wrench size? A 1/2" wrench is used on a 5/16 bolt. Most studs that I've use are coarse thread that goes into the intake and fine thread up top.


Sent from my iPhone using Tapatalk
 
My nuts are fine thread, 7/16 socket. The cars didn't come with a 1/2" nut on the carb. Just sayin'

For me, the intake dosn't get hot enough to melt or damage the nylon. I've never had an issue with it anyway.
 
Nuts shouldn't be vibrating loose once they have been tightened, unless there is a major gap or flaw in how the carb fits to the spacer and/or the intake manifold. They should vibrate as a single unit...

If the threads are damaged or the nut threads are damaged, then they might vibrate loose, but they should also not be able to be torqued. I found no torque spec in my 66 FSM.
 
For a 5/16" fine thread grade 2 bolt the torque spec is 12 ft-lbs. If it's a grade 5 nut/bolt then the torque would be 19 ft-lbs.
 
"Midlife" said:
Nuts shouldn't be vibrating loose once they have been tightened, unless there is a major gap or flaw in how the carb fits to the spacer and/or the intake manifold. They should vibrate as a single unit...

If the threads are damaged or the nut threads are damaged, then they might vibrate loose, but they should also not be able to be torqued. I found no torque spec in my 66 FSM.
Click to expand...
That is what is confusing the Hell out of me. The old carb with the same spacer and nuts never had the problem. But since putting on the second new one with the same base, spacer and nuts, they appear to be backing off, I snug them down and after a run they have room to re-snug. So I thought I might try to eliminate the ability to back off even though they are not supposed to.
 
Holley says for the 4150 DP that I have:

"2. Place the carburetor in position over the four stud bolts and secure in place. To avoid warping the carburetor flange, tighten each bolt
gradually. Tighten in a criss cross pattern to 60 in./lbs. Be careful not to overtighten the nuts."
 
The studs will expand and contract with temperature changes, causing the nuts to loosen eventually. Use split lock washers.
 
"Starfury" said:
The studs will expand and contract with temperature changes, causing the nuts to loosen eventually. Use split lock washers.
Click to expand...
Did just that with some Red thread lock..so far, so good.
 
Red Loctite......isn't that permanent or at least requiring a bunch of heat to get loose? Maybe my mind is slipping....
 
You must log in or register to reply here.
Back
Top