2bbl to 4bll swap advice needed

Blown4.6 · Dec 25, 2003

I just bought a'68 fastback with a 351W out of a '74 LTD. It currently is running only a 2bbl carb.

To say the least, it's a bit sluggish. Does anyone have any idea about

1) what 4bbl carb (if any) will bolt right up to the stock manifold
2) if I need a new manifold, what is a good one?
3) what about a new cam now that it will breath better? What kind of duration at .050 would be good (PLEASE KEEP IN MIND I AM RUNNING PWR STEERING, BRAKES AND A/C.....so I need a little vacuum)?

Also, what kind of power increases would you expect from just a 2bbl to 4bbl, manifold and headers?

Thanks!!

302 coupe · Dec 25, 2003

intake: performer rpm or weiand stealth
carb: edelbrock or holley 600 cfm, vac. secondaries
cam: for good idle, max dur@50 will be about 220, so aim for a little under that, and about 480 lift

add some long tube headers and good exhaust, you should be lookin at about 290 hp along with some real good torque for a street car, probably around 350-360 ft-lbs somewhere around 3500 rpm.

xoxbxfx · Dec 25, 2003

302 coupe said:
intake: performer rpm or weiand stealth
carb: edelbrock or holley 600 cfm, vac. secondaries
cam: for good idle, max dur@50 will be about 220, so aim for a little under that, and about 480 lift

add some long tube headers and good exhaust, you should be lookin at about 290 hp along with some real good torque for a street car, probably around 350-360 ft-lbs somewhere around 3500 rpm.

I couldnt agree more... I suggest a performer RPM and a 600cfm holley. You might even go 650cfm carb incase you upgrade a little more later.

Stang_1973 · Dec 25, 2003

I too have been looking into this and found that there is an adapter that allows you to put a 4bbl carb on a 2bbl intake.

I would say though, if you can, go ahead and swap the intake.

As for for cam suggestions I dont know and hope this thread will help me as well.

I also remember reading in another thread, that if you adjust, (I think), the ignition timing, you will feel a difference but i really wouldn't know much about doing this. Maybe some one can clarify.

xoxbxfx · Dec 25, 2003

Stang_1973 said:
I too have been looking into this and found that there is an adapter that allows you to put a 4bbl carb on a 2bbl intake.

I would say though, if you can, go ahead and swap the intake.

As for for cam suggestions I dont know and hope this thread will help me as well.

I also remember reading in another thread, that if you adjust, (I think), the ignition timing, you will feel a difference but i really wouldn't know much about doing this. Maybe some one can clarify.

putting a 4bbl carb on a 2bbl intake isnt going to do you any good... Dont waste your money on the adapeter...its its a waste and its like 2" tall...

my66coupe · Dec 25, 2003

Before slamming the engine with all this performance, I would recommend a compression or a leak down test. For carbs I recommend either a holley or a Edelbrock 600 and up. The weiand stealth is a great intake.

Mike

D.Hearne · Dec 26, 2003

One more option: If you want the performance of the 4 bbl but don't want to swap intakes, or use adapters ( 4bbl to 2bbl intake is bad, 2 bbl on a 4 bbl intake OK and the adapter isn't 2" tall, just 1") You might want to consider a Holley list # 4412 500 cfm 2bbl. It is a bolt on replacement for the Ford 2bbl and will net you about 20-30 hp. I would also recommend a cam swap in that 74 motor, if it hasn't been changed from stock. A cam like the Crane Energizers or a Comp cams High energy series would be a good choice.

Blown4.6 · Dec 26, 2003

All great advice!! I think I'll go with the 2bbl holly 500 cfm. That plus a better cam and headers should do fine. I just want to drive this motor until it goes. Then, I'll likely build a 351W-427W stroker. For now, dropping $1K is about where I'd like to keep it on the motor.

Thanks!

D.Hearne said:
One more option: If you want the performance of the 4 bbl but don't want to swap intakes, or use adapters ( 4bbl to 2bbl intake is bad, 2 bbl on a 4 bbl intake OK and the adapter isn't 2" tall, just 1") You might want to consider a Holley list # 4412 500 cfm 2bbl. It is a bolt on replacement for the Ford 2bbl and will net you about 20-30 hp. I would also recommend a cam swap in that 74 motor, if it hasn't been changed from stock. A cam like the Crane Energizers or a Comp cams High energy series would be a good choice.

67efivert · Dec 27, 2003

r u gonna do the work?
if so find a good used carb 100-150 used intake 50-125
new cam and lifters 150 misc gaskets 75 headers 100
should make a good torquey motor

2bbl to 4bll swap advice needed

Blown4.6

302 coupe

xoxbxfx

Stang_1973

xoxbxfx

my66coupe

D.Hearne

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Blown4.6

67efivert

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