The Stovebolt Site Forums The Shop Area Engine Shop best 4 barrel for 250

Dudes!

What's the best 4 barrel to run with a stock cam, crank and piston 250? I'm thinking a Holley 390 or Holley 450 cfm. I only plan on running a single carb. Suggestions?

Should I even fool with a rebuild or just cough up the 250+ bucks for a newbie?

-ftyler

Ftyler, at once I build a high performance 250 for a frined of mine, 10/1 CR, 290' cam, Clifford intaje and a 390 double pumper, that I found used in a swap meet at Old Bridge Township Raceway Park (E-town, NJ), it was just perfect for the porpose, but used a lot of gas. There is a Holley 450cfm, mec. secondaries but no pump in the rear, and single inlet. I see that this is the carb for a stock 250. But may require some jetting job.

Ftyler;

What are your goals for changing out a carb? Mileage? Performance? Driveability? Your answer will help determine the right carb. Will you consider a 2 bbl?

Darrell

dude!

Glad you asked. I am now definitely in the market for a 2bbl. Got a great deal on an Offy 5416 intake that had a 2bbl adapter on it.

In order of importance, I'd say that I'm looking for

1) Driveability
2) Mileage
3) Performance

This is going to be a street/daily driver. Never dragging or on the strip. I'd like to be able to retain good interstate on-ramp acceleration and yet get the best mileage possible on the highway. What's your suggestion?

If the holley 350cfm does fit the manifold tou're looking at, I guess it would be a good choice for overall driveability, performence and if You care to tune it properly, it may even show somw good fuel economy numbers.

Ftyler;

I asked the identical question of Tom Langdon of Stovebolt engine Part Company http://www.stoveboltengineco.com/ His response to the question was a Holley Webber progressive 2 BBL either on a 2 BBL manifold or use a 2 bbl to 1 bbl adapter and use your stock intake. Do any of you have experience with this carb and want to offer a second opinion?
I found a site that talks about them at length: http://users.mwci.net/~raykarpi/duster/holley.htm. The 280 CFM mentioned should be enough for a 250 turning 4000 rpm or so. It is slightly larger than the original 1 bbl. and since it is a progressive design should increase both driveability and economy.

Darrell

I have had experience with those carbs, using two on my 261 engine. a single carb will give better mileage and better wide open performance.But at part throttle, running on the small primary of the staged 2 bbl, will reduce throttle response and power.I know a few guys who ran one with those results. An older Rochester 2bbl like the 2CG? works well.Andre's suggestion of a Holley 350 will also work nicely. I tested a number of small 4 bbl carbs on my 261 engine using a Clifford heated manifold.I used a shut off on the water heat to test both heated and non heated operation.I gave results in past posts about the carbs.My person opinion is for street use, a dual carb set up is the better than a single 4bbl of the same CFM.The Clifford 4bbl intake, the only one avaiable for my engine has too large a plenumn for low speed street use the way my engine is tuned.The large plenumn fools the engine into thinking the carb is larger. Perhaps a 250 will respond differently.