I just got a new vehicle with a 1974 400 in it with the stock 2Bbl carb. It really leaks, and my options are rebuilding it or getting a new aftermarket 4Bbl. Generally, putting a 4Bbl and new manifold on a car enhances performance, but I was at the wreckers the other day and the guy there strongly advised against it because he said the 400 was one of ford's lousier engines and a 4 bbl would just be a waste of gasoline. What do you guys say?

 

Alex88,

I would argue against the 4V carb, if that's the only thing you're considering doing.

The main thing the 400 needs to improve its power is a decent camshaft. Simply adding a 4V carb and intake to a stock engine will not make much improvement. For about the same or less cost, you can switch out the cam, lifters, and valve springs (to support more valve lift) keep a 2V carb, and get more bang for the buck than the 4V carb swap.

Rebuilding the Motorcraft 2150 2V carb is a piece of cake, not that difficult even for a novice. Rebuild kits run $20-40, depending on the parts shop prices in your neighborhood.

A lot of people rag on the 400 because it was never developed for high performance from the factory, and most of its production lifespan ('71-'82) was during the period Ford turned its corporate back on the high performance and motorsport world. Since the 400's hp was rated from 160-170 after 1971 (SAE net ratings), you can easily double the factory power level with off-the-shelf components. Of course, it takes more than just a carb and camshaft to do that.

BubbaF250

1980 F250 4x4 Custom, 351M/NP435/NP208/D44HD-TTB/D60-FF/3.55s 6750 GVW, Rust & White.

 

A 4v carburetor is never a waste of money. The extra capacity of a 4v to dump more gas into the engine will always produce more power. But you should also consider a hotter cam (I've heard good things about a 268 degree profile, which is pretty mild still) and definitely get a new timing set. Most 400s had the camshaft timing retarded to help with emission control (at the cost of performance and fuel economy--doesn't make much sense to me), so changing that out will increase the gains that the bigger carburetor brings to your engine.

You might consider getting the complete Edelbrock Performer package for the engine. Should only cost $600 or so for the intake, carb, and cam and lifters. Or you can get just the cam and intake and find or buy another brand of carburetor. Don't get too big of a carb, though, becuase this may have a tendency to limit your low end torque (not enough vacuum to open secondaries when primaries are too big). 600 cfm should be good enough.