Fuel Economy of Autolite 2100 vs. Holley 5200 Carbs

[briansz]

Is anybody actually running an Autolite 2100 carb that can offer an average mpg with it for the 2.3 motor?

My truck is:

'83 2wd longbed
TK5 Tranny
7.5 Rear with 3.73's
'87 2.3 Block .030 over, decked .010, forged pistons/balanced
'83 head ported and gasket matched, decked .020
Comp Cams .420 lift hydraulic slider cam
Cannon 2bbl Intake from Esslinger
Holley 5200 from '70's Stang, manual choke, Edelbrock foam air cleaner
Cast tube header
Factory EFI fuel tank and in-tank fuel pump
Stock Duraspark dist and ignition box
Emissions - ha ha ha, that's funny

This motor is much snappier than the stock one, it pulls almost any hill at highway speeds in 5th no problem while the old stock engine with 1bbl needed to drop into third and struggled. It runs like a bear but I'm still lacking some torque below 3000 RPM.

Trying to decide if I want to get an Trans-Dapt adapter plate and run a 1.02 or 1.08 venturi 2100 carb ($30 plus some fab time) or if I should just get a cam gear ($100 plus some install time) to bring down the power band with the 5200. I have multiple carbs of each type so their cost isn't a factor.

Last tank running the 5200 I actually broke 20mpg - 20.3mpg to be exact, and according to my air/fuel meter I could probably go one jet size leaner up here at altitude with no problems and gain a little more.

Obviously with the cost of fuel I do not want to drop economy a bunch. Looking for real-world experiences from other members who run the 2100. Some guy a while back said he was getting 25mpg but I can't locate the post...............

 

[John Smith]

Do you have ..

Sounds like you've got a great motor for experimenting there some. I've considered the same question. I actually am interested in a 0.98 venturi if i can find one. I'm getting closer to putting one of my motors in my B2 project and could use either manifold at this point but my own research has kinda led me to think I won't be running enuf of a modified motor to get the benefit form TOO much carb...

I've got a cple 2100 venturi bodies i would trade for a good 0.98 to try...In my case with an oval port manifold it's bolt on...

How's that "in tank" pump situation working out?..This next week I'm going to do something about that but not sure what yet..

BTW, another option maybe might be to use an actual Weber 32/36 38 variant, actually progressive either vacuum or manual opening secondarys...I guess you can order any variety you want for shaft rotation orientation etc...and it is infinatley tunable for this size CU..another option on the table

 

[kimcrwbr1]

Autolites are the most efficient as they vaporize the fuel more thorough you just need to make sure the venturi and jet sizes are appropriate for your engine you dont want to run it too lean or you will burn valves and or pistons the only thing that cools them is the fuel air mix.

 

[briansz]

Sounds like you've got a great motor for experimenting there some. I've considered the same question. I actually am interested in a 0.98 venturi if i can find one. I'm getting closer to putting one of my motors in my B2 project and could use either manifold at this point but my own research has kinda led me to think I won't be running enuf of a modified motor to get the benefit form TOO much carb...

I've got a cple 2100 venturi bodies i would trade for a good 0.98 to try...In my case with an oval port manifold it's bolt on...

How's that "in tank" pump situation working out?..This next week I'm going to do something about that but not sure what yet..

BTW, another option maybe might be to use an actual Weber 32/36 38 variant, actually progressive either vacuum or manual opening secondarys...I guess you can order any variety you want for shaft rotation orientation etc...and it is infinatley tunable for this size CU..another option on the table

I could never find a 0.98. That would probably be best. Might need a spacer on the oval-port manifold, from memory mocking it up I don't think the 1.02 butterflies clear at WOT without one. I've got a 1.02 I picked up an electric choke for, I may give it a try before the 2.3T transplant.

 

[John Smith]

I could never find a 0.98. That would probably be best. Might need a spacer on the oval-port manifold, from memory mocking it up I don't think the 1.02 butterflies clear at WOT without one. I've got a 1.02 I picked up an electric choke for, I may give it a try before the 2.3T transplant.

Good point about the spacer..and actually i had decided to use one anyway to raise it up some ...1-2" or so..I just acquired an 1.08, and 1.23 body...spares..and I've got a somewhat rebuild-able 1.08 2150 as well but maybe i can scout around for .98" in y area. Also, how about doing some epoxy work on the the venturi bores?...kinda like "make ur own"..custom venturi size....well something to think about..

About the adj cam gear, i have acquired one used...and i guess 2-6 degrees might help. Also if you DID adjust ur cam..you might be able to "dial it in" a little closer after "decking" the block and head...at least you'd know exactly where ur at...

 

[John Smith]

about venturi resizing

I could never find a 0.98. That would probably be best. Might need a spacer on the oval-port manifold, from memory mocking it up I don't think the 1.02 butterflies clear at WOT without one. I've got a 1.02 I picked up an electric choke for, I may give it a try before the 2.3T transplant.

Out of curiosity, i called Pony Carbs today to ask about .98 venturi carb availability..(66 221 fairlane vintage)..they said.."almost non-existant"..so if you find one..bronze it i guess...also the say they have ability to resize venturi's with sleeves...which can make a 1.01 out of any of them i guess...something to think about...if you have a good 1.02 wiht a good shaft..might be worth a try...if you like that carb footprint and have the manifold...after some thinking about it, i think i'll just use the 5200/weber variant i have and be open to buying a newer Weber variant if i have issues with my older carb body. At least you can buy any combo you want and pretty cheaply too...and it will "bolt on"...and you can use a pretty little chrome air cleaner.....

I also looked into the availability of a a Stromberg 97, (Holley 94) for the pure fun of it..and actually iy began to make sense....

When you consider loosing the "puter" ($100), EFI harness ($100), EFI fuel pump(s) ($250), that new "97" would only set u back $25

http://www.stromberg-97.com/index.html

Talk about a bargain.....i think there would be something special about THAT carb on one of these motors....now if i could just find one of those valve covers reasonable and swap my "turbo" one for it.....