4bbl intake question

Bigtommy,

I suspect you have a 225, not a 170. The head used on a 225, which is just a stroked 170, is the same as the one on a 170. It doesn’t breath as well as it could on the larger displacement 225.

Best bang for the buck would be increasing compression to 9-9.2 from stock 7.9-8.1., and a distributor re-curve so it will run on mid grade fuel.

Increasing carburetion is unnecessary unless you have improved the stock engines breathing. A stock engine just can’t take full advantage of a carburetor much larger than the one barrel it came with from the factory. It can only suck in just so much air, and push it out the tail pipe. A carburetor that has a higher cfm rating than what an engine can move is over sized, won’t improve performance, and in some cases if it is a lot bigger, it will hurt performance.

You will need to increase air flow through the engine, a project that can be expensive. One needs to increase compression, install over sized valves, bowl port, valve relive, gasket match, upgrade intake to a 2v or 4v manifold.

Exhaust enlargement is next; to get more air in, one has to get more air out of the engine. Dutra Duals or Headers, into a “Y” pipe, single 2 ¼” or 2 ½” back to axel to a free flowing muffler, and out to the bumper with a slightly smaller tail 2” pipe.

Now that you have the engine breathing a lot better, a larger cam with more overlap is needed, and still more static compression added, because with more cam overlap, dynamic compression drops. Compression drops, performance drops along with it. So one needs to hit the online engine calculators to figure out what has to be done.

Now you can plop on a 4V carburetor and get some performance out of it.

As for connecting kick down & throttle cables; there are several ways to easily accomplish it. I took the Bouchillon Performance rout with a Holley 390.

Now you have the engine pulling real good, the drive train has to be upgraded with higher stall torque converter, and 3.55 - 4.11 rear gears… It goes on and on… $$$$$$$$$

So set a goal, take advantage of online calculators and make a plan that works for you, and let the fun begin. Also take a look over at slantsix.org.