Holley 390 - Thead size

[martin_t]

Hi

Can anyone tell me the thread size for the bolt\stud that holds the air filter into the body of the Carb on the Holley 390?

Thanks

Martin

[dingocooke]

I'm 99.9% sure its same as the bigger holleys; ie 1/4 UNF.
If you use studding, wind a 1/4 UNF nyloc onto it and when you have screwed the studding in to the carb wind the nyloc down and nip to the carb body; this stops the age old holley problem of the stud unscrewing and wobbling around until the monkey metal wears out and the stud falls out!
Steve