Hot Rod Forum banner
1 - 7 of 7 Posts

·
Banned
Joined
·
1,533 Posts
Discussion Starter · #1 · (Edited)
Fellas,

I have a 750 vac. secondary carb in my garage that I am goiong to be selling. I was working on it and had the vac. diaphragm cover off to verify which spring was in it. A little ball bearing fell out and I have lost it. I can't seem to find any info in manuals or books that tells me what size it is, is it metal or plastic, and what it does. I think is a check ball but am not sure. I don't want to sell the carb to somebody and not have it complete. Anybody got any ideas about this?
 

·
WFO
Joined
·
5,030 Posts
cool rockin daddy said:
Fellas,

I have a 750 vac. secondary carb in my garage that I am goiong to be selling. I was working on it and had the vac. diaphragm cover off to verify which spring was in it. A little ball bearing fell out and I have lost it. I can't seem to find any info in manuals or books that tells me what size it is, is it metal or plastic, and what it does. I think is a check ball but am not sure. I don't want to sell the carb to somebody and not have it complete. Anybody got any ideas about this?
It's a 3/16" steel check ball that is there to act as a kind of damper so the secondary action isn't too abrupt.
 

·
WFO
Joined
·
5,030 Posts
cool rockin daddy said:
Thanks Cobalt. 3/16 steel. Perfect. Just place it in the bottom and seal it up?
That's it! ;)

BTW, the check ball isn't supposed to seal perfectly, otherwise the vacuum can't get to the chamber above the diaphragm to actuate the 2'ndaries. Also, don't forget the little cork seal between the housing and carb body that seals the vacuum port.

A tuning aid, is to use different balls (smaller, or aluminum, etc.) and/or to purposely "nick" the check ball seat to allow a larger orifice to affect the rate and timing of the opening of the 2'ndaries- beyond what can be done w/just the springs.
 

·
Google "Tunnel Ram 406"
Joined
·
1,137 Posts
cobalt327 said:
That's it! ;)

BTW, the check ball isn't supposed to seal perfectly, otherwise the vacuum can't get to the chamber above the diaphragm to actuate the 2'ndaries. Also, don't forget the little cork seal between the housing and carb body that seals the vacuum port.

A tuning aid, is to use different balls (smaller, or aluminum, etc.) and/or to purposely "nick" the check ball seat to allow a larger orifice to affect the rate and timing of the opening of the 2'ndaries- beyond what can be done w/just the springs.

I used an old hot rodders trick. I would use a Phillip screw driver that will fit in hole and tap it with a small ball pin hammer and this added four grooves. This will let more air to bypass the check ball. :)
 
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top