Thread: carb replacment

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Hey, i have an 86 F-350 with the 460. The current carb on it is a 4180 holly carb. I went to the auto store and got a new one, a double pumper 4160. My question is will these carb work on that motor. The old carb is a 600 cfm and the new one is a 750. what are your suggestions.

should be able to tune it in for the 460, 600 seems small for a 460 anyway. the 750 should work fine.

If the truck's an automatic you'll have problems with a double pumper, mechanical secondaries.

it is an auto, why would i have problems with the secondaries and are they all mechanical? What if it's vacuum secondaries like the one i have?

your torque will probably suffer if you use a double pumper. its more down the high rpm street. vac secondaries are much better for most street vechicles with auto as it only opens the secondaries when the primaries are nearly at full capacity. this means at low rpm the air speed through the carb is higher, (smaller hole effectively) so torque is much better.

seems like a 750 vac secondary is just wat u need. 600cfm is prob very restricting for a 460 at high rpm

lobster

A double pumper carb responds according to the whims of the driver. For a heavy vehicle at low speeds and low stall converter, when you bury the throttle the engine could be over-whelmed by fueld resulting in a low end bog or stumble.

A vacuum secondary carb responds to the need of the engine regardless of position of the primary throttle. It can be adjusted to come on quickly or slowly depending on what vacuum springs you use.

Here is a photo of my Barry Grant 870 Speed Demon with electric choke on a ZZ502 engine. A 750 cfm version of this would probably be a great carb for your 460.

Kitz

Im thinking about getting a new carb, but i dont have vacuum advnace hooked up. Will the vacuum secondaries work the same or will it be just like a double pumper?

thanx
david

The vacuum secondaries don't care what the ignition is. They respond only to air demands from the engine, and will open as far as far as the primary throttle is opened at any particular time.

The vacuum carb has a vacuum advance port just like the double pumper; there's no difference with ignition timing .........

Kitz

oh, ok. My bad. Thanx.