The Stovebolt Site Forums The Shop Area Engine Shop wanted, carb for a 1967 gmc 351 v6

I have read that bolting on a holley 500 two barrel carb to my gmc 351 v6 is the way to go, but where do I get the adapter to do the swap?

The short answer:

There used to be, and maybe still is, a company in California called Trans-Dapt that made the adapter.

The long answer (or to quote Paul Harvey, the rest of the story):

Several years ago, we read/heard/whatever the same thing about replacing the Stromberg with the Holley. Since we own what is left of Stromberg, we had customers asking about the swap. So we bought 6 of the adapters and 6 of the Holleys; and sold them all in the summer. During the summer, all was well, except the gas mileage decreased dramatically from the Stromberg, but the trucks ran OK. And then winter came, and to start the trucks, the choke must be used. And every miserable one of the chokes BROKE on the Holleys. We had to take every one of them back and refund the full purchase price! And since they were broken, Holley would not take them back from us. Worst financial decision I have ever made!!!!!

I threw them all in a used 20 gallon garbage can (literally) and sold the can and its contents for the price of a new garbage can to a circle track racer.

So make the change if you want, but I would highly suggest rebuilding and keeping your original Stromberg if you want to drive the truck in the winter!

Jon.

Will a 500 CFM Rochester work?

The large Rochester world require a different adapter, but yes, it could be made to work; but why???

If you are looking for reliability, the Stromberg has only one reliability issue, the aluminum throttle body. Once a competant rebuilder has installed bushings to prevent throttle shaft/throttle body wear; they are bullet-proof! And the larger Strombergs came from the factory with roller-bearings which totally eliminated this issue.

If you are hot-rodding the engine, the Strombergs came in a variety of venturii sizes, and were used on G.M.C. V-6's up to 478 CID and EVERYTHING STILL FITS!

The Strombergs have one major disadvantage (shared by the Rochester) when compared to the Holley. Every parts store in the world has Holley parts; and don't carry Stromberg or Rochester parts. But both the Stromberg and Rochester parts are readily available mail order.

We have been selling the Strombergs to Buick, Cadillac, and Packard owners of mid-1930's cars for lots of years, because they are so reliable, and often much less expensive than the original.

But yes, Trans-Dapt probably had an adapter to replace the Stromberg with the larger Rochester.

Jon.

I used a mr.gasket adapter part number 1937 with the holley 500 cfm, no problems yet this winter driving it almost daily