i have a couple questions pertaining to a holley model 4175 650 cfm carburetor....

the particular carb i have here came from an early 80's fullsize
chevy pickup with a 305 in it.

first thing i notice is that there are no provisions on the outside for adjusting the float levels. how does one adjust the float level on this one?

next question, how different from a 4160 is this carb? what i'm really wanting to know is can the adjust-a-jet kits for a 4160 be used on this carb?

i'm considering on whether to rebuild this carb for my 305, then transfer it to the 350 i want to build, or just save up for a new carb.

 

This spreadbore holly is not the factory carb for a 80's pickup but
is a suitable replacement for the factory Qjet.

The float height is not adjustable from the outside like other holleys.
You have to remove the fuel bowl and set the float height and
float drop with a float guage. I don;t know the actual spec.

They actually rarely got out of wack unless the float is damaged
or someone tweeked it.

The metering blocks ae simular to 4150/4160 holleys but not the same. Holley may have an adjust a jet kit for this 4175 style carb.

Thses are good carbs for mild to moderate street performance motors up to about 375/390 HP.
They work best when used on a spreadbore syle intake that does not require an adapter.
The q-jet spreadbore version of the Performer RPM would be a good example.
Weiand makes two good street performance Spreadbore intakes too.
#8000 dual plane (very simular to the Stealth intake)
and 7525 single plane Team G.

A GM ZZ4 intake would be a good one also.

 

fbird:

thanks for the tips

the 350 i'm wanting to build is possibly going to want more carb than this 650..

the latest catalog i have is a couple years old, and didn't list a adjustajet kit for the 4175.

i may just save my money for a demon....