Stromberg 97 with ported vacuum

DSC_0726We have added an important new capability to our 97 model carburetor – a ‘ported vacuum’ source for your vacuum advance distributor. Available as an option (add -VP on to the usual carb part numbers) it is available on the full range of Stromberg 97 carburetors – in stock on the regular OE finish and to special order on Chrome, Black and Barn Find models. Ported vacuum capability is also available in a new replacement base casting (throttle body), complete with all new throttle shaft and plates, idle needle screws, kicker linkage and choke lever. Available only from Stromberg Carburetor, it’s the perfect swap-in for any 97.

Genuine Stromberg 97 with vacuum port – Part Number 9510A-VP
New 97 base with vacuum port (comes with gaskets) – Part number 9514-VP

Developed in-house here at Stromberg Carburetor, the new vac-port equipped 97s provide vacuum through a small brass fitting located just behind the kicker linkage on the same side of the carburetor base (throttle body) as the typical small-block Chevy distributor vacuum canister. The fitting can be replaced with a small set screw (supplied) if engine needs change.

Like our cable choke and ‘push-throttle’ options, the new vacuum port makes it easier to use 97s in so many applications. To test the effects on our 350ci Chevy dyno motor, we disconnected the vacuum and locked the throttle at 1800rpm. Once reconnected, the vacuum-induced additional timing raised rpm to 2000 and increased torque by 4 ft-lb – all without adding more gas, of course. The exhaust sound changed considerably, too, so it obviously appreciated the extra timing.

Tech note: Unlike manifold vacuum, ‘ported vacuum’ is taken from just above the throttle plate to provide additional, vacuum-activated timing advance only at light load/part throttle conditions and not at idle or full throttle. Claimed benefits of vacuum advance include improved fuel economy and throttle response. Most aftermarket vacuum advance distributors are designed to work with ported vacuum, though the technical specification should always be checked. And of course, multiple 97 applications need only one vac-port equipped carburetor.

The new Genuine Stromberg 97 with vacuum port and the new vac port-equipped 97 base are available through the worldwide Stromberg dealer network. Further details, including pricing, and help with installation is available from us here at Stromberg by email or via the Stromberg Tech Center at