My '69 F100 Ranger has the original 4.9l motor with a 2bbl Holley. I don't know what cfm the 2bbl is but odds are its original. Will I pick up power switching out to a 600 cfm with vacuum secondaries? There's an adapter to go from 2bbl to 4bbl and I'm curious if anyone has done this swap and gained power

 

I think 600 cfm might be a little big for that 6, my 390 ran perfect with the 600. Maybe a smaller 2 bbl like the 500?

 

Yea 500 max. Holley makes a 390 4bbl that works great.

Otherwise I'd recommend sticking with a 350cfm 2100 autolite

 

Upsize/upgrade the exhaust before upgrading the induction side of the engine.

Then a 390 cfm or 500 cfm carb with a vacuum secondaries.

 

300'S NEVER CAME WITH A 2v. What intake and/or adaptor you already have?

 

The 300 never came with a 2v carburetor. It came with the 1v Carter YF. Your 2v Holley is not original. It's either a 350cfm Holley P/N 7448 or a 500cfm Holley P/N 4412C, but chances are that it's the former. What intake manifold do you have? The factory log intake requires a fair bit of modification to allow a 2v carburetor to be put in place. I'm hoping you have an aftermarket intake on there, especially if you're planning to move up to a 4v. The 600cfm carburetor is too large. The recommended 4v is the 390cfm Holley 4160, P/N 8007. The 8007 will yield more gains over anything else, especially when tuned right. The only time a bigger carburetor might be necessary is if you do some extensive internal improvements to the engine. There are some people though that have used an Edelbrock 500cfm carburetor with simple intake/exhaust upgrades and noticed good results, but the general consensus is that a 390cfm Holley is what you want.

The best thing you can do is learn about what you have before you begin to change it.

FTE Ford Inline Six, 200, 250, 4.9L / 300

FordSix.com 240-300 "Big Block" Six Performance

 

Like the guys said the 300 never came stock with a 2V. If it's stock it's a 1V carb.

Unless you are doing a performance build, a good set up for a driver is the following:

1. Like HIO Silver mentioned upgrade the exhaust side. A good swap is a pair of stock EFI ( came on 87-96/7 4.9L's ) exhaust manifolds. They are basically a pair of cast iron shorty headers. That also gives you the option of either running a Y-pipe for a single exhaust or you can run true dual exhaust with them.

2. Up grade to an aftermarket intake. I like the Offenhauser C-series intake ( not the Offenhauser DP ) . Or a good second choice is a Clifford Performance intake if you can find a good deal on a used one on Ebay.

3. Add a 4V to 2V carb adapter and run an Autolite 2100 or Motorcraft 2150 2V carb. I prefer the Autolite 2100 because it's a little simpler carb then the 2150's. But either will work. For a single 2V set up try to find either a 1.08, 1.14 or 1.23 sized carb. These carbs came stock on Ford V8's from the 60's thru early 80's. You can pick them up cheap and rebuild them for a lot less then buying a new carb.




If you want a new carb you might as well go with a 4V. There is no problem running a 600 cfm 4V on the 300. You will notice very little if any difference between a 600 and the 500 cfm carb. The 600 is not too big for a 300. They actually run quite well with them. Check out the inline 6 forum Ford Inline Six, 200, 250, 4.9L / 300 - Ford Truck Enthusiasts Forums . There is more then one person running a 600cfm carb on the 300's.

I would personally stay away from the 390 cfm 4V on the 300's. They can be a pain to get to run right on the 300. And just don't offer much of any benefit over a larger carb. And how many guys do you see running a 390 cfm 4V on a 302 V8??

 

IIRC, FTE guy hillcountrylft outta central TX has a pair of EFI exhaust manifolds available.

 

The 390 is hard to tune because it's a Holley. Everything is adjustable.

 

None... but a 300 characteristically has a different HP/TQ curve than a 302... TQ at lower RPMs rules the street and offroad and that's where the 300 excels.

But yeah, the 500 cfm would compensate for any potential shortcomings. A really oversized carb however, would be like flushing a toilet down a one-inch drain.

 

I come at it from another angle. I would go 4V. The 500 Holley Super Deuce has large throats and venturis. Great for high RPM and flow but lousy for small Cube engines wanting some sort of fuel economy. The air and gas don't atomize well in the small air velocity and large throats world. With the stock cam it won't use much of the secondaries of the 4V. But with trying different secondary springs of a Holley you can tailor in just as much secondary opening as your particular engine can handle. If you want a 4150 with jets in the secondaries then go with a 570CFM list #80570. If you want a 600CFM 4160 with a secondary metering plate there are a miriad of Holley list number carbs out there. But remember the exhaust side as mentioned above. WHAT GOES IN HAS TO COME OUT.

 

I've got a pair I'd be willing to sell too!



The Holley 390 cfm 4V is better suited for a small engine. Like a 2.3L 4 cyl.!!




Yea but a 300 sounds pretty wicked turning 7,000+ rpms too!


Technically a 300 with an aftermarket intake is more like flushing a toilet down six one-inch drains! We're talking about a 600 cfm carb here not a 1050 cfm dominator. The main reason I would say go for a 600 over a 500 is, they are more readily available and can be found cheaper then a 500 ( if buying used ) . And running a 600 is not going to cause a problem.




A 300 isn't really a small displacement engine. You are talking about an engine that has 50 cubic inch cylinders. The same as the 400.

 

We can't discuss this any more before we know what he wants out of his engine.

 

And what else he is or isn't going to do. I still say 600 is too big.

 

Have you tried one on a 300?







He doesn't need to worry about a 4V period if he still has a stock intake. Stacking a 2V to 4V adapter on top of a 1V to 2V adapter is just a bad idea on top of bad idea.