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Installing Dual Stromberg 97's On A GMC 305A

By Cort Corino, Astoria, Oregon.


2- Stromberg 97 carburetors

1- Vintage Speed Y-manifold P/N FL-CA-4

1- Progressive Linkage P/N CL-2X2-P (Vintagespeed.com)

1- Rochester to Stromberg pattern adapter P/N 5605159 (The Hot Rod Co.)

2- Helmet air cleaners P/N 91011025 (The Hot Rod Co.)

1- Holley Fuel Pressure Regulator P/N 12504 (The Hot Rod Co.)

1- Stromberg banjo fitting P/N 9082K (The Hot Rod Co.)

1- Stromberg banjo fitting P/N 9083K (The Hot Rod Co.)

2- Heim joints P/N 732-1131 (NAPA)

1- 1/4-28 All thread for throttle linkage

3- 5/16 inverted flare fittings

1- 5/16 tubing

1- Custom fuel regulator bracket

1- 5/16 fuel hose


After procuring all of the afore mentioned parts, the installation went pretty smooth. It was important
to me not to cut or modify any OEM parts. That way I can restore the truck later on with all the
original components, if so desired.

First I located a later model 2-barrel V-6 intake to work with the adapters. My 305A originally had
the One-Barrel Holley 1907. After installing the new intake, I bolted up all of the adapters & then
the carbs. I made a custom bracket to mount the fuel regulator as close as possible to the carb, while
also keeping asthetic appeal. I used 5/16 brake line bought from NAPA, & made a line from the pump
to the regulator & then from the regulator to the primary carb. I did not hard pipe the second fuel
line to the primary carb, instead I used about 2-3" of 5/16 fuel hose. Just a preference.

From there I routed the original choke cable to the passenger side & it actually had enough reach
to choke the primary carb fully open & closed. I made another custom bracket for the choke
cable which bolted to the secondary carb.

Finally I installed two Heim Joints to a 1/4-28 all thread to connect my throttle linkage on the carb
to the factory linkage from the accelerator pedal.

Because Stromberg's have no provision for vacuum advance, I installed a vacuum fitting to the rear
of the manifold & connected it directly to the advance mechanism on the distributor. Having manifold
vacuum full time to the distributor seems to really make the engine happy at idle. After a performace run,
this engine has never been more responsive & smooth at idle. I am extremely happy with the end results.

Lastly, The whole assembly will stick about 2-3" above the hood. To facilitate this, I have removed the hood &
am in the process of finding another hood I am confortable with cutting to allow the air cleaners to clear.
I couldn't bear the thought of cutting my original "eye-brow" hood.

That is basically the gist of it. The whole process took about 6 hours, stopping for a snack & a parts run.

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