About economy

[John Smith]

I found a post today that discusses jet sizes for older carbed 2100 ultra small early v8's...and found a source for even smaller jets than 46's....evidentley some engines at altitude actually used 38's-44's....it seems that very early carbs prior to 63 used similar jets threads to Holly so if ur swapping jets some schooling may be in order to a very early carb...i have a hunch a 2150 with 46's may be a little rich..some experimenting my be in order..

http://www.tffn.net/phpBB3/viewtopic.php?f=58&t=23437

"Yes sir, according to Mannel, all '63 and prior 2100/4100 carbs used the smaller threaded (Holley-like) jets. From '64-up were the larger Ford-only jets.

Allstate Carburetor only sells the larger threaded jets...I guess Holley jets would work for C3 and earlier carbs if replacements were needed."

http://www.allcarbs.com/detail.php?pid=159&gb=1&ctgn=27&stt=0

 

[06RangerXLT]

im sorry, what are yout trying to do? drive on top of the rockies?

 

[John Smith]

no not the rockies...

But some here have decided to run a carb..and instead of the usual "put a 4.0/v-8 in it" have chosen to "run what they brung" (2.8L)..and economy is still factor for many..

I know the prevailing mentality here is to "put 37's on it..etc..but i think a lot of guys still have to drive'm to work...and choose these rigs for other reasons..of course w/o fuel injection.."you might need to fine tune..even for prevailing altitude..now if you lived in the Rockies...

 

[John Smith]

The complaint about the 2.8L seems

to be no power, no economy, but need to duraspark it etc...and since I'm doing this to one of mine..i thought maybe some comments bout the potential for better economy might be appropriate..

I have a hunch that the typical 1.08 venturi carb may be actually too big. If you believe some CFM charts...this motor may well not need more than about 240 or so for cfm for average use.(or less)..and so using the following...

Stamped No + CFM

.98=190
1.01=240
1.02=245
1.08=287
1.14=300
1.21=351
1.23=356
1.33=424

I had in my possession a pre-64 1.01 so i will use that with the recommended 38-42 jets for a small v-8 and see how that works...and "reading the pugs old school" may tell if even that is too rich or not...just for conversation...my hope is if it is jetted right for cfm/cubic inches it will also run better...and also have more response...

This motor might actually run better with a Holley/Weber varaint..32/36 etc..the adapter is only about 45$ or so..

 

[dangerranger83]

Our carbs ARE rated at 240CFM now, Ford put the right ones on them from the factory and if you go duraspark and get the non feed back motorcraft 2150 or 2100, then you are still at 240CFM but not having a computer control it.

Our engines can only move just above 300CFM through them a minute, in a perfect universe that is, at max RPM.

 

[John Smith]

I'm sure ur right ..

about it being able to move that much cfm..full out..but i wonder how efficient it may be at around 2K rpm where gearing rpm for economy/cruise...which could be more like 100 or so cfm give or take...just how efficent is that carb at that cfm?..again nobody really worries about when 4 wheeling ..as long as it "gets me up that next hill"..? maybe a little trial and error might better that?...at least it's a carb i already have so nothing spent to see..

Our carbs ARE rated at 240CFM now, Ford put the right ones on them from the factory and if you go duraspark and get the non feed back motorcraft 2150 or 2100, then you are still at 240CFM but not having a computer control it.

Our engines can only move just above 300CFM through them a minute, in a perfect universe that is, at max RPM.

 

[dangerranger83]

Its not just a matter of CFM's but also not leaning out the engine or starving it to where it would do worse trying to fight the wind. As for 2,000 rpm thats nothing when the max torque is at 2,600 rpm and max HP is at 4,600 rpm. I try to shift mine around the max torque area when I can.