391 Carburetion
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From: Tennessee
391 Carburetion
Hi guys, I am interested in your thoughts on a new carb for my 72 Ford 7000 with a 391. Some prior owner has removed the original carb with it's governor, and replaced it with a 1850-2 (600 cfm?), and I was wondering if anyone might have an idea as to what was original on this truck.
I began to think back on the old trials bikes I had owned and they had VERY small carbs (24mm) as compared to the enduro models (30mm) or the MX which was huge (36mm). The trials bikes were intended to produce lots of torque, as compared to the MX's high speed horses.
If I were to place a 390 cfm carb on the truck, would that be sufficient to provide enough fuel for an engine that size, or am I just way off base.
Any ideas would be valuable to me, and also I thought it might provoke a good argument for the bulletin board.
Thanks, Bob
I began to think back on the old trials bikes I had owned and they had VERY small carbs (24mm) as compared to the enduro models (30mm) or the MX which was huge (36mm). The trials bikes were intended to produce lots of torque, as compared to the MX's high speed horses.
If I were to place a 390 cfm carb on the truck, would that be sufficient to provide enough fuel for an engine that size, or am I just way off base.
Any ideas would be valuable to me, and also I thought it might provoke a good argument for the bulletin board.
Thanks, Bob
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I don't really know about the 390 cfm carb being big enough...
but you are right about the trial bike thing... small barrells are used for good throttle response, while large barrells are better for top end. Thus the primary barrells on a 4 barrell carb being smaller than the secondaries...also along the lines of the V-boost Yamaha used on V-Max's.
but you are right about the trial bike thing... small barrells are used for good throttle response, while large barrells are better for top end. Thus the primary barrells on a 4 barrell carb being smaller than the secondaries...also along the lines of the V-boost Yamaha used on V-Max's.
Last edited by 76390FE; Nov 25, 2003 at 10:41 PM.
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From: Iowa
The 600cfm vacuum secondary holley (correct me if I'm wrong) should be perfect on that engine. Just get a rebuild kit, holley calls it a "trick kit," and rebuild it if it needs it.
A 390cfm carb would probably be a little too small for a 391. Although now that I think about it, 391's dont rev all that high, and a 390cfm carb might work. I think you've got a good one though, and I wouldn't worry about it. But that's just me!
A 390cfm carb would probably be a little too small for a 391. Although now that I think about it, 391's dont rev all that high, and a 390cfm carb might work. I think you've got a good one though, and I wouldn't worry about it. But that's just me!
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