• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!

    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
  • When posting a classified ad, you MUST select a prefix from the drop-down next to the subject line. If you don't you will get an error and your ad will not be posted!
Tips
Tips

Stromberg Carburater Damper

pware

Senior Member
Offline
OK guys I have a dumb question. What is the purpose of the damper. I am assuming I am talking about the damper. The cylender that moves up and down at the air intake of the carb. Is it the choke? I havent taken mine apart yet for a rebuild... so I am not that familer yet with the carb. I am used to chevy carbs with a buterfly valve. Just cureous.
 
Hi there. I think you are referrign to the piston. The piston helps control the amount of fuel that goes into the engine. The high it rises into the housing the more fuel that comes up out of the jet since the needling is being pulled up.
 
The cylinder visible at the intake is not the damper, nor the choke. These are what are known as "variable venturi" carburetors (or "constant depression" if you are British :G) and that cylinder forms the top of the venturi. Chevy never used variable venturis, although ISTR Ford experimented briefly in the late 70s with them (before moving on to EFI).

Basically, the piston rises in response to air flow into the engine, to keep the air velocity through the venturi constant. It also lifts a mixture needle, which is tapered to keep the mixture more-or-less constant as the venturi size increases.

The 'damper' goes in the middle of the air piston (that big nut on top of the carb), and slows the movement of the air piston. Serves as roughly the equivalent of an accelerator pump, to compensate for the mixture otherwise going lean as the throttle is opened.

ZS carbs had two different types of 'choke' mechanism, I'm not sure offhand which one would be found on a 69 GT6. One kind is a half-round bar that rotates in front of the venturi and partially blocks it; but the more common type is a valve on the side of the carb that opens additional fuel jets for richer mixture.
 
I think the type of choke Randall is describing for the Strombergs is the "starter bar" used on early models like the CD2 and I believe that's what's on my '67 GT6. I only think that style was used for a year or so. The carbs on a '69 are likely to be different.

To add a bit to what's been said above, the name "damper" is somewhat self-explanatory. It's the piston "thing" that is inserted into the oil poured into the top of the carb. The vacuum piston moves up and down in response to the air flow as Randall mentioned and the oil in the dashpot assembly controls the rate at which the vacuum piston can move "up". The viscous oil helps control the mixture during acceleration. People will try all sorts of oils to obtain a "feel" they like during acceleration.
 
Doug said:
People will try all sorts of oils to obtain a "feel" they like during acceleration.

And usually settle on simply adding whatever goes into the crankcase as the path of least resistance. :wink:
 
Yes ford did experiment with the variable venturi carb.
Had one on a 1980 Merc Marquis...biggest piece of fuel control crap ever made.
it got replaced by a standard ford 2 bbl carb.
 
Thanks for all the info guys. This really cleared alot up for me.
 
Back
Top